Showing 1–50 of 668 results for author: Wu, X

Discovery of an odd-parity f-wave charge order in a kagome metal

Authors: Jiangchang Zheng, Caiyun Chen, Ruiqin Fu, Luca Buiarelli, Zihan Lin, Fazhi Yang, Tianhao Guo, Ganesh Pokharel, Andrea Capa Salinas, Sen Zhou, Turan Birol, Stephen D. Wilson, Junzhang Ma, Daniel J. Schultz, Xianxin Wu, Berthold Jäck

Abstract: The spontaneous breaking of symmetries is a cornerstone of physics, defining the phases of matter from the cosmological scale to the quantum realm. In condensed matter, electronic orders are classified by their behavior under fundamental symmetries like spatial inversion (parity). While even-parity orders, such as conventional superconductivity and charge density waves, are ubiquitous, their odd-p… ▽ More The spontaneous breaking of symmetries is a cornerstone of physics, defining the phases of matter from the cosmological scale to the quantum realm. In condensed matter, electronic orders are classified by their behavior under fundamental symmetries like spatial inversion (parity). While even-parity orders, such as conventional superconductivity and charge density waves, are ubiquitous, their odd-parity counterparts--predicted to host exotic phenomena such as gapless quasiparticle excitations and novel collective modes--are comparatively elusive states of quantum matter. Here, using high-resolution scanning tunneling microscopy and angle-resolved photoemission spectroscopy on the kagome metal CsV$_3$Sb$_5$, we report the discovery of an inversion symmetry-breaking $f$-wave charge bond order. We show that this phase, which preserves translation symmetry, is stabilized by the spontaneous opening of a spectral gap at a previously overlooked Dirac point, providing a textbook condensed-matter realization of the Gross-Neveu model for dynamical mass generation and parity breaking. Intriguingly, this $f$-wave order is itself a intervening phase, vanishing abruptly below a temperature of 10\,K and pointing to a subsequent transition into a `hidden' electronic state that is invisible to local STM probes. Our findings establish odd-parity charge order as a novel phase of matter, here, embedded within the intricate hierarchy of correlated electronic orders on the kagome lattice. △ Less

Submitted 15 April, 2026; originally announced April 2026.

Comments: 5 figures

Raman response in superconducting multiorbital systems with application to nickelates

Authors: Matías Bejas, Jun Zhan, Xianxin Wu, Andreas P. Schnyder, Andrés Greco

Abstract: The recent discovery of high-$T_c$ superconductivity in pressurized and thin film nickelates is nowadays one of the most relevant and active topics in solid-state physics. The origin of superconductivity together with the relevance of multiorbital physics are highly discussed issues in this field. Knowledge of the size of the gap and its symmetry is of fundamental interest to uncover the supercond… ▽ More The recent discovery of high-$T_c$ superconductivity in pressurized and thin film nickelates is nowadays one of the most relevant and active topics in solid-state physics. The origin of superconductivity together with the relevance of multiorbital physics are highly discussed issues in this field. Knowledge of the size of the gap and its symmetry is of fundamental interest to uncover the superconducting mechanism at play in the nickelates. Electronic Raman scattering is a powerful tool to investigate the main characteristics of the gap. Here, we investigate the Raman response in the superconducting phase for three different models: Two-orbital models, including $d_{x^2-y^2}$ and $d_{z^2}$ orbitals, with one and two layers; as well as a bilayer model with the $d_{x^2-y^2}$ orbital as the only active one. For each of these models, we consider different pairing symmetries and determine their characteristic fingerprints in the Raman response. For the two-orbital models, we perform full multiorbital calculations including interorbital and intraorbital scattering, and compare the results with those obtained using the additive Raman response where each band is considered separately. Our results should be useful for discussing the minimal model for superconductivity and its pairing symmetry in nickelates. The obtained results and discussions, as well as the presented formalism, are also of general interest for other multiorbital systems. △ Less

Submitted 13 April, 2026; originally announced April 2026.

Comments: 11 pages, 6 figures

Journal ref: Phys. Rev. B 113, 144504 (2026)

Visualizing the interplay of dual electronic nematicities in kagome superconductors

Authors: Yunmei Zhang, Jun Zhan, Ping Wu, Yun-Peng Huang, Qixiao Yuan, Hongyu Li, Zhuying Wang, Wanru Ma, Shuikang Yu, Kunming Zhang, Wanlin Cheng, Deshu Chen, Minrui Chen, Tao Wu, Ziji Xiang, Xianxin Wu, Zhenyu Wang, Xianhui Chen

Abstract: Kagome superconductor AV$_3$Sb$_5$ (A stands for K, Rb, and Cs) hosts a wealth of intertwined electronic orders driven by geometric frustration and electron correlations. Among them, the breaking of rotational and/or time-reversal symmetry, observed within the triple-$Q$ charge density wave (CDW) phase yet exhibiting a more complex temperature dependence, remains a central puzzle. Here, by using s… ▽ More Kagome superconductor AV$_3$Sb$_5$ (A stands for K, Rb, and Cs) hosts a wealth of intertwined electronic orders driven by geometric frustration and electron correlations. Among them, the breaking of rotational and/or time-reversal symmetry, observed within the triple-$Q$ charge density wave (CDW) phase yet exhibiting a more complex temperature dependence, remains a central puzzle. Here, by using scanning tunneling microscopy to study the electronic structures of CsV$_3$Sb$_5$ as a function of temperature and Ti doping, we disentangle the interrelation between two distinct nematic order parameters, one associated with the CDW and the other manifested as $C_2$ distortion of the V-$d_{x^{2}-y^{2}}$ Fermi pockets without breaking transition symmetry. The latter persists to high doping levels and high temperatures where the long-range CDW is fully suppressed. Moreover, its nematic director is oriented in a lattice direction distinct from that of the CDW-induced nematicity at intermediate doping, and eventually aligns with the strong nematic CDW order in the pristine compound where the quasiparticles of vanadium orbitals become coherent below a lower characteristic temperature. These observations, combined with Ginzburg-Landau analysis, reveal a rich interplay between two nematic orders that can be assigned to distinct kagome-lattice orbitals. Our results shed new light on the enigmatic intertwined orders in this family and establish a rare material platform in which dual nematic orders coexist and couple to give rise to unusual correlated phenomena. △ Less

Submitted 7 April, 2026; originally announced April 2026.

Comments: 14pages, 5 figures;

Detecting pairing symmetry of bilayer nickelates using electronic Raman scattering

Authors: Jun Zhan, Matías Bejas, Andreas P. Schnyder, Andrés Greco, Xianxin Wu, Jiangping Hu

Abstract: The recent discovery of high-temperature superconductivity in both bulk and thin-film bilayer nickelates La$_3$Ni$_2$O$_7$ has garnered significant attention. However, the corresponding pairing symmetry remains debated in both experiments and theoretical studies due to conflicting experimental evidence from bulk and thin-film materials. In this work, we examine the electronic Raman response across… ▽ More The recent discovery of high-temperature superconductivity in both bulk and thin-film bilayer nickelates La$_3$Ni$_2$O$_7$ has garnered significant attention. However, the corresponding pairing symmetry remains debated in both experiments and theoretical studies due to conflicting experimental evidence from bulk and thin-film materials. In this work, we examine the electronic Raman response across different channels for various pairing symmetries within a two-orbital bilayer model. By comparing Raman susceptibilities obtained from multiorbital and band-additive approaches, we demonstrate that Raman response can distinguish between different pairing symmetries and identify pocket-dependent gap amplitudes for both fully gapped and nodal superconducting states. Specifically, the nodal $d_{x^2-y^2}/d_{xy}$-wave pairing exhibits robust low-energy power-law behavior, distinct from a fully gapped pairing. Additionally, for the $s_{\pm}$-wave pairing, the detailed gap anisotropy on the $β$ pocket can be determined. Possible experimental implications are also discussed. Our results highlight the crucial role of multiorbital effects in shaping the Raman spectra and establish electronic Raman scattering as a powerful and symmetry-resolved probe for determining the superconducting gap in unconventional superconductors. △ Less

Submitted 1 April, 2026; originally announced April 2026.

Comments: 8 pages, 6 figures

Journal ref: Chin. Phys. Lett. 43 020706 (2026)

Magnetic doping-induced second-order and first-order topological phase transition inthe photonic alloy

Authors: Xianbin Wu, Tiantao Qu, Xiaoxuan Shi, Lei Zhang, Jun Chen

Abstract: The bulk-edge correspondence principle, a cornerstone of topological physics, ensures that first-order topological systems host robust chiral edge states in two dimension. This was later extended to higher-order phases, where second-order topological insulators exhibit localized, topologically protected corner states. While the transition between these distinct phases has been demonstrated in peri… ▽ More The bulk-edge correspondence principle, a cornerstone of topological physics, ensures that first-order topological systems host robust chiral edge states in two dimension. This was later extended to higher-order phases, where second-order topological insulators exhibit localized, topologically protected corner states. While the transition between these distinct phases has been demonstrated in periodic systems, its existence in disordered platforms remains an open question. Here, we demonstrate a controllable topological phase transition between a second-order topological phase and a first-order topological phase in a two-dimensional photonic alloy. By tuning the magnetic doping concentration - implemented by attaching permanent magnets randomly to nonmagnetized yttrium iron garnet rods in an alternately magnetized honeycomb lattice with C3 rotational symmetry - we flexibly control the system's topology. At zero doping, we observe higher-order corner states, confirmed by a trivial Chern number and non-zero bulk polarizations of 1/3. As doping concentration increases, these corner states progressively merge with the bulk states, culminating in the closure of the bulk transmission gap. After the bulk transmission gap reopens with further increased doping, the system transitions to a first-order topological phase, characterized by a nontrivial Chern number of -1 and the emergence of a chiral edge state. This transition is reversible, providing a highly tunable and experimentally simple platform for flexibly switching between localized corner states and delocalized chiral edge states within a single photonic system. △ Less

Submitted 29 March, 2026; originally announced March 2026.

Journal ref: Phys. Rev. B 113, 104205 (2026)

Anomalous Hall Conductivity as an Effective Means of Tracking the Floquet Weyl Nodes in Quasi-One-Dimensional $β$-Bi$_4$I$_4$

Authors: Qingfeng Huang, Shengpu Huang, Tingyan Chen, Jing Fan, Dong-Hui Xu, Xiaozhi Wu, Da-Shuai Ma, Rui Wang

Abstract: While Floquet engineering offers a powerful paradigm for manipulating topological phases, particularly Floquet Weyl semimetals, establishing an experimentally feasible strategy for tracking the dynamic evolution of such states remains a significant challenge. Here, we propose that the anomalous Hall effect (AHE), as a sensitive, all-electrical probe, can be used to track Floquet Weyl nodes. Using… ▽ More While Floquet engineering offers a powerful paradigm for manipulating topological phases, particularly Floquet Weyl semimetals, establishing an experimentally feasible strategy for tracking the dynamic evolution of such states remains a significant challenge. Here, we propose that the anomalous Hall effect (AHE), as a sensitive, all-electrical probe, can be used to track Floquet Weyl nodes. Using first-principles calculations and symmetry analysis on the quasi-one-dimensional material $β$-Bi$_4$I$_4$, we demonstrate that circularly polarized light breaks time-reversal symmetry, driving the system from a trivial insulator into a Floquet Weyl semimetal phase characterized by a nonzero Berry curvature flux. Crucially, by continuously tuning the polarization phase $\varphi$ of the driving field, we show that the trajectory of the induced Weyl nodes is highly controllable, leading to their migration and eventual annihilation at high-symmetry points. We reveal that the anomalous Hall conductivity maps directly onto this topological evolution, serving as a definitive fingerprint for the generation and dynamics of Weyl nodes. △ Less

Submitted 29 March, 2026; originally announced March 2026.

Multiple Topological States in LaAgAs2, a Failed Square-Net Semimetal

Authors: Yang Liu, Tongrui Li, Xixi Yuan, Nour Maraytta, Alexei V. Fedorov, Asish K. Kundu, Turgut Yilmaz, Elio Vescovo, Xueliang Wu, Long Zhang, Mingquan He, Yisheng Chai, Xiaoyuan Zhou, Michael Merz, Zhe Sun, Huixia Fu, Tonica Valla, Aifeng Wang

Abstract: The rational design of new materials emerges as an important direction to explore new topological materials, which is based on the understanding of the correlation between crystal and electronic structures. In this paper, we perform a comprehensive study on the crystal and electronic structures in LaAgAs2 through a combination of single-crystal x-ray diffraction (XRD), quantum oscillation, and ang… ▽ More The rational design of new materials emerges as an important direction to explore new topological materials, which is based on the understanding of the correlation between crystal and electronic structures. In this paper, we perform a comprehensive study on the crystal and electronic structures in LaAgAs2 through a combination of single-crystal x-ray diffraction (XRD), quantum oscillation, and angle-resolved photoemission spectroscopy (ARPES) experimental measurements, and density functional theory (DFT) calculations. Single-crystal XRD measurements reveal that LaAgAs2 crystallizes into a HfCuSi2-derived structure with the square net distorted into cis-trans chains. Quantum oscillation measurements reveal two frequencies with small effective masses and quasi-two-dimensional (2D) characters. ARPES measurements reveal an electronic structure strikingly different from the square-net-based semimetals, such as LaAgAs2. The Fermi surface is quasi-two-dimensional (2D), with Dirac-like hole pockets at the zone center and a quasi-1D elliptical electron pocket at the zone boundary. Based on the DFT calculations, the measured electronic structure can be well understood regarding the cis-trans distortion, which transforms the two-dimensional square net-derived Dirac bands into quasi-1D trivial bands. Intriguingly, multiple topological states can be identified around the zone center, including a nontrivial Z2 topological surface state and a bulk Dirac state. Our study clarifies the impact of cis-trans distortion and identifies LaAgAs2 as a topological material with multiple topological states near the Fermi level, providing a guideline for intentionally designing new topological materials. △ Less

Submitted 25 March, 2026; originally announced March 2026.

Comments: 33 pages, 7 figures. Accepted by npj Quantum Materials

Lattice-Expansion-Driven Stabilization of Helical Magnetic Order in Ru-Doped MnP

Authors: Xin-Wei Wu, Deng-lu Hou, Li Ma, Cong-mian Zhen, De-wei Zhao, Guoke Li

Abstract: The practical utilization of MnP in chiral spintronic devices is fundamentally constrained by its low helical ordering temperature ($T_{\rm S}$). Here, we demonstrate that Ru substitution in Mn$_{1-x}$Ru$_x$P single crystals drives a highly anisotropic lattice expansion, where the $b$-axis elongation is one-quarter that of the $a$- and $c$-axes ($\sim$ 0.04 Å). This structural distortion profoundl… ▽ More The practical utilization of MnP in chiral spintronic devices is fundamentally constrained by its low helical ordering temperature ($T_{\rm S}$). Here, we demonstrate that Ru substitution in Mn$_{1-x}$Ru$_x$P single crystals drives a highly anisotropic lattice expansion, where the $b$-axis elongation is one-quarter that of the $a$- and $c$-axes ($\sim$ 0.04 Å). This structural distortion profoundly stabilizes the helical ground state, elevating $T_{\rm S}$ from 51~K to 215~K and the critical field along the [010] direction at 5~K from 2.3 to 30.0~kOe, while suppressing the Curie temperature ($T_{\rm C}$) from 291~K to 215~K. Synthesizing these results with reported data on Mo- and W-doped analogues reveals that $T_{\rm S}$ and $T_{\rm C}$ are governed primarily by the $b$-axis parameter, exhibiting universal linear scaling relationships ($dT_{\rm S}/db = 1.59 \times 10^4\ \text{KÅ}^{-1}$, $dT_{\rm C}/db = 0.69 \times 10^4\ \text{KÅ}^{-1}$) far greater than those associated with the $a$- or $c$-axes. First-principles calculations reveal that the lattice expansion selectively attenuates ferromagnetic coupling while preserving antiferromagnetic interactions between nearest-neighbor Mn atoms, thereby enhancing magnetic frustration and stabilizing helimagnetism. These findings establish chemical pressure via directed $b$-axis engineering as a robust, generalizable paradigm for stabilizing helimagnetism in MnP. △ Less

Submitted 25 March, 2026; originally announced March 2026.

Programmable, Spontaneous Superlattice Memory in a Monolayer Topological Insulator

Authors: Jian Tang, Thomas Siyuan Ding, Shuhan Ding, Jiangxu Li, Changjiang Yi, Tianxing Tang, Zumeng Huang, Xuehao Wu, Zhiheng Huang, Birender Singh, Tiema Qian, Vsevolod Belosevich, Mingyang Guo, Anyuan Gao, Nikolai Peshcherenko, Zhe Sun, Mohamed Shehabeldin, Kenji Watanabe, Takashi Taniguchi, Abhay N. Pasupathy, Claudia Felser, Kenneth S. Burch, Ni Ni, Yao Wang, Yang Zhang , et al. (2 additional authors not shown)

Abstract: Memory is a foundational concept across disciplines, from neurobiology and electronics to artificial intelligence and quantum gravity. In materials, memory effects typically arise from ferroic orders, such as ferroelectricity and ferromagnetism, where information is stored in charge or spin degrees of freedom. Here, we report a surprising discovery of a nonvolatile superlattice memory effect in mo… ▽ More Memory is a foundational concept across disciplines, from neurobiology and electronics to artificial intelligence and quantum gravity. In materials, memory effects typically arise from ferroic orders, such as ferroelectricity and ferromagnetism, where information is stored in charge or spin degrees of freedom. Here, we report a surprising discovery of a nonvolatile superlattice memory effect in monolayer TaIrTe4, a dual quantum spin Hall insulator, where information is encoded through sharply contrasting lattice periodicities. In particular, in a pristine monolayer, we observe the spontaneous emergence of a long-period superlattice that can be programmed ON and OFF in a nonvolatile manner by electrostatic tuning of low-energy electronic states. This switching toggles the system between two structural configurations with unit cell areas differing by nearly two orders of magnitude. Mechanistically, our results reveal two independent and distinct instabilities, one in the lattice and the other in the QSH electrons, which are coupled, leading to electrostatic control of lattice configurations with nonvolatile memory. This finding is enabled by combining linear and nonlinear transport measurements, Raman spectroscopy, and scanning tunneling microscopy, which probe complementary aspects of the underlying orders. Remarkably, this nonvolatile memory effect stabilizes a spontaneous superlattice with a periodicity on the few-nanometer scale that remains robust across a wide doping range, persists over days, and survives above 70 K. Combined with the QSH topology, this stability offers a promising route to nonvolatile memory control of topological flat bands and their filling enabled quantum states. Our preliminary data indeed show the emergence of new insulating states at fractional superlattice fillings, which can be clearly switched ON and OFF together with the superlattice. △ Less

Submitted 19 March, 2026; originally announced March 2026.

Comments: 33 pages, 16 figures, submitted version

GPUMDkit: A User-Friendly Toolkit for GPUMD and NEP

Authors: Zihan Yan, Denan Li, Xin Wu, Zhoulin Liu, Chen Hua, Boyi Situ, Hao Yang, Shengjie Tang, Benrui Tang, Ziyang Wang, Shangzhao Yi, Huan Wang, Dian Huang, Ke Li, Qilin Guo, Zherui Chen, Ke Xu, Yanzhou Wang, Ziliang Wang, Gang Tang, Shi Liu, Zheyong Fan, Yizhou Zhu

Abstract: Machine-learned interatomic potentials have revolutionized molecular dynamics simulations by providing quantum-mechanical accuracy at empirical-potential speeds. The graphics processing unit molecular dynamics (GPUMD) package, featuring the highly efficient neuroevolution potential (NEP) framework, has emerged as a powerful tool in this domain. However, the complexity of force field development, a… ▽ More Machine-learned interatomic potentials have revolutionized molecular dynamics simulations by providing quantum-mechanical accuracy at empirical-potential speeds. The graphics processing unit molecular dynamics (GPUMD) package, featuring the highly efficient neuroevolution potential (NEP) framework, has emerged as a powerful tool in this domain. However, the complexity of force field development, active learning, and trajectory post-processing often requires extensive manual scripting, imposing a steep learning curve on new users. To address this, we present GPUMDkit, a comprehensive and user-friendly toolkit that streamlines the entire simulation workflow for GPUMD and NEP. GPUMDkit integrates a suite of essential functionalities, including format conversion, structure sampling, property calculation, and data visualization, accessible through both interactive and command-line interfaces. Its modular, extensible architecture ensures accessibility for users of all experience levels while allowing seamless integration of new features. By automating complex tasks and enhancing productivity, GPUMDkit substantially lowers the barrier to using GPUMD and NEP programs. This article describes the program architecture and demonstrates its capabilities through practical applications. △ Less

Submitted 18 March, 2026; originally announced March 2026.

Comments: 17 pages, 7 figures

The Python Simulations of Chemistry Framework: 10 years of an open-source quantum chemistry project

Authors: Qiming Sun, Matthew R Hermes, Xiaojie Wu, Huanchen Zhai, Xing Zhang, Abdelrahman M. Ahmed, Juan José Aucar, Oliver J. Backhouse, Samragni Banerjee, Peng Bao, Nikolay A. Bogdanov, Kyle Bystrom, Frédéric Chapoton, Ning-Yuan Chen, Ivan Yu. Chernyshov, Helen S. Clifford, Sander Cohen-Janes, Zhi-Hao Cui, Yann D. Damour, Nike Dattani, Linus Bjarne Dittmer, Sebastian Ehlert, Janus Juul Eriksen, Francesco A. Evangelista, Simon A. Ewing , et al. (78 additional authors not shown)

Abstract: Over the past decade, the Python-based Simulations of Chemistry Framework (PySCF) has developed into a widely used open-source platform for electronic structure theory and quantum chemical method development. This article reviews the major advances since the previous overview in 2020, covering new modules and methodology, infrastructure changes, and performance benchmarks. Over the past decade, the Python-based Simulations of Chemistry Framework (PySCF) has developed into a widely used open-source platform for electronic structure theory and quantum chemical method development. This article reviews the major advances since the previous overview in 2020, covering new modules and methodology, infrastructure changes, and performance benchmarks. △ Less

Submitted 7 April, 2026; v1 submitted 14 March, 2026; originally announced March 2026.

Fractional topology in open systems

Authors: Xi Wu, Xiang Zhang, Fuxiang Li

Abstract: We investigate the emergence of fractional topological invariants in a periodic Su-Schrieffer- Heeger chain subject to gain and loss, governed by the Gorini-Kossakowski-Sudarshan-Lindblad master equations. After preparing the symmetry condition for integer topological invariants, we investigate their transition to fractional ones in steady states, which can happen either by tuning parameters in ju… ▽ More We investigate the emergence of fractional topological invariants in a periodic Su-Schrieffer- Heeger chain subject to gain and loss, governed by the Gorini-Kossakowski-Sudarshan-Lindblad master equations. After preparing the symmetry condition for integer topological invariants, we investigate their transition to fractional ones in steady states, which can happen either by tuning parameters in jump operators or as a dynamical transition during time evolution. Moreover, we show that these fractional topological invariants no longer possess quantized topology in the conventional sense. However, by extending the Brillouin zone to cover multiple cycles, the total winding regains integer quantization. Finally, we show how such effects can be observed in long-range hopping photonic lattices with fractional fillings, via Bloch state tomography. Our results open a new pathway to understand fractional topology in open quantum systems. △ Less

Submitted 4 March, 2026; originally announced March 2026.

Ab initio electronic conductivity of Fe-bearing post-perovskite

Authors: Yihang Peng, Yupei Zhang, Shuai Zhang, Chenxing Luo, Donghao Zheng, Nelson Naveas, Xifan Wu, Jie Deng

Abstract: The electrical conductivity of high-pressure silicates profoundly influences the interior dynamics of rocky planets. Employing the Kubo-Greenwood formalism, we perform ab initio calculations of electronic conductivity in Fe-bearing post-perovskite under super-Earth mantle conditions, up to 4000 K and 500 GPa. Electronic structures are obtained via many-body perturbation theory, incorporating dynam… ▽ More The electrical conductivity of high-pressure silicates profoundly influences the interior dynamics of rocky planets. Employing the Kubo-Greenwood formalism, we perform ab initio calculations of electronic conductivity in Fe-bearing post-perovskite under super-Earth mantle conditions, up to 4000 K and 500 GPa. Electronic structures are obtained via many-body perturbation theory, incorporating dynamical screening and correlations among localized Fe-3d orbitals. In contrast to (Fe,Mg)O, for which metallization has been reported at comparable conditions, our results indicate that post-perovskite with Earth-like Fe contents is unlikely to metallize in super-Earth mantles via band-gap closure, yielding negligible low-frequency conductivity. Any substantial conductivity would require non-electronic mechanisms, such as thermally activated small-polaron hopping, which fall beyond the scope of band conduction. △ Less

Submitted 26 February, 2026; originally announced February 2026.

Hydrostatic Pressure-enhanced correlated magnetism and Chern insulator in moir'e WSe2

Authors: Pengfei Jiao, Chenghao Qian, Ning Mao, Xumin Chang, Jiayong Xiao, Feng Liu, Shaozheng Wang, Xiaokai Wu, Di Peng, Cheng Xu, Hongliang Dong, Yuchen Zheng, Juncai Wu, Tong Zheng, Kenji Watanabe, Takashi Taniguchi, Jinfeng Jia, Xiaoxue Liu, Zhiwen Shi, Shiyong Wang, Guorui Chen, Tingxin Li, Ruidan Zhong, Yang Zhang, Dong Qian , et al. (2 additional authors not shown)

Abstract: Moiré semiconductors offer flat bands where Coulomb interactions and band topology intertwine, while interlayer coupling plays a central role in forming the moiré potential. However, limited interlayer coupling strength and the lack of efficient tuning methods hinder further exploration of correlated phenomena in moiré semiconductors. Here we introduce a cryogenic dual-gated diamond-anvil platform… ▽ More Moiré semiconductors offer flat bands where Coulomb interactions and band topology intertwine, while interlayer coupling plays a central role in forming the moiré potential. However, limited interlayer coupling strength and the lack of efficient tuning methods hinder further exploration of correlated phenomena in moiré semiconductors. Here we introduce a cryogenic dual-gated diamond-anvil platform using helium as a pressure medium, enabling reversible hydrostatic tuning together with magneto-optical spectroscopy in twisted bilayer WSe2. Pressure enhances the moiré potential, redshifts excitons, and stabilizes Stoner ferromagnetism otherwise absent at a 3.1-degree twist. Simultaneously, the half-filled C = 1 Chern insulating state strengthens, exhibiting a reduced saturation field. Moreover, we observe a topological phase transition from a Chern insulator to a Mott insulator at around 2 GPa. First-principles calculations reveal that a Gamma-to-K valence-band-maximum switching drives this transition by converting an Ising-like topological K-valley miniband into a spin-degenerate trivial Gamma miniband. Our findings demonstrate hydrostatic pressure as a powerful, continuous control axis for correlated magnetism and topological band engineering in moiré materials. △ Less

Submitted 17 February, 2026; originally announced February 2026.

Microstructural origin of the simultaneous enhancements in strength and ductility of a nitrogen-doped high-entropy alloy

Authors: Xiaoxiang Wu, Zhujun Sun, Wenqi Guo, Chang Liu, Yong-Qiang Yan, Yan-Ning Zhang, Yuji Ikeda, Fritz Körmann, Jörg Neugebauer, Zhiming Li, Baptiste Gault, Ge Wu

Abstract: As one of the most abundant interstitial elements, nitrogen (N) is effective in improving yield strength of metallic materials, due to interstitial solid solution strengthening. Doping N can substantially enhance the yield strength but often leads to a decreased ductility, revealing a strength-ductility trade-off phenomenon. Here, we simultaneously enhance the strength and ductility in a non-equia… ▽ More As one of the most abundant interstitial elements, nitrogen (N) is effective in improving yield strength of metallic materials, due to interstitial solid solution strengthening. Doping N can substantially enhance the yield strength but often leads to a decreased ductility, revealing a strength-ductility trade-off phenomenon. Here, we simultaneously enhance the strength and ductility in a non-equiatomic CrMnFeCoNi high-entropy alloy via N alloying and unravel the underlying microscopic mechanisms. The N-doped alloy (1 at.% N) shows an excellent combination of higher yield strength (104% increase) and larger ductility (38% increase), with a two-stage strain hardening behavior, compared to the N-free alloy. Detailed transmission electron microscopy (TEM) analysis reveals that N-doping introduces short-range order (SRO) domains within the microstructure, leads to pronounced planar slip, and promotes the formation of nano-spaced (6-15 nm) stacking faults and deformation twins. Continuous generation and interaction of the fine-spaced SFs act as a strong barrier for dislocation movement and provide ample room for dislocation storage. The interaction of SRO with dislocations and the evolution of SFs ascribe to the first strain hardening stage, and the disordering of the SRO along with the activation of deformation twins are attributed to the second strain hardening stage. Our work shows that N-doping is effective in simultaneously improving the strength-ductility synergy and provides novel insights into alloy design with slightly elevating the SFE, and manipulating the ordered structure within the HEA. △ Less

Submitted 10 February, 2026; originally announced February 2026.

Journal ref: Acta Mater. 304, 121753 (2025)

Room Temperature Collective Blinking and Photon Bunching from CsPbBr3 Quantum Dot Superlattice

Authors: Qiwen Tan, Sudipta Seth, Boris Louis, Xiayan Wu, Nithin Pathoor, Toranosuke Takagi, Shun Omagari, Takumi Sannomiya, Johan Hofkens, Martin Vacha

Abstract: Development of quantum light sources and search for quantum systems capable of supporting collective many-body states are crucial for further progress of modern quantum technologies. Metal halide perovskite quantum dots (QDs) have emerged as a promising candidate for quantum light sources, as individual QDs are reliable single photon emitters even at room temperature. However, photon bunching, a k… ▽ More Development of quantum light sources and search for quantum systems capable of supporting collective many-body states are crucial for further progress of modern quantum technologies. Metal halide perovskite quantum dots (QDs) have emerged as a promising candidate for quantum light sources, as individual QDs are reliable single photon emitters even at room temperature. However, photon bunching, a key signature of collective many-body states, has been so far largely observed at cryogenic temperatures in perovskite materials, limiting their applications under ambient conditions. Here, we report the observation of collective blinking and photon bunching in perovskite QD superlattices at room temperature. Sub-wavelength-sized (100 - 500 nm) CsPbBr3 QD superlattices, fabricated via a self-assembly process, exhibit an unusual two-level blinking behavior similar to that of single QDs, and demonstrate photon bunching with a degree of up to 2.75. Time-resolved photoluminescence (PL) measurements and super-resolution imaging reveal that the superlattices have a significantly longer PL lifetime than individual QDs and that their emission is spatially confined to regions tens of nanometers in size. These observations suggest long-range exciton migration to a localized energy trap within the superlattice. Excitation power dependent degree of bunching and analysis of the bunching dynamics indicate that the photon bunching originates from exciton-biexciton cascade emission, a key mechanism for generating entangled photons. These findings establish perovskite QD superlattices as a promising platform for room-temperature collective optical phenomena and quantum light generation, advancing scalable quantum photonic technologies. △ Less

Submitted 3 March, 2026; v1 submitted 9 February, 2026; originally announced February 2026.

New solution to the hyperon puzzle of neutron stars: Quantum many-body effects

Authors: Hao-Fu Zhu, Guo-Zhu Liu, Xufen Wu, Ye-Fei Yuan

Abstract: The hyperon puzzle refers to the challenge of reconciling the existence of hyperons in neutron star cores and the observed high masses of neutron stars. The recent discovery of PSR J0952-0607 ($2.35\pm0.17 M_{\odot}$) has intensified this challenge. Existing solutions fail to achieve such a high mass, and often predict unrealistically fast cooling that is at odds with observations. Here, we propos… ▽ More The hyperon puzzle refers to the challenge of reconciling the existence of hyperons in neutron star cores and the observed high masses of neutron stars. The recent discovery of PSR J0952-0607 ($2.35\pm0.17 M_{\odot}$) has intensified this challenge. Existing solutions fail to achieve such a high mass, and often predict unrealistically fast cooling that is at odds with observations. Here, we propose a novel solution to the hyperon puzzle. Using the Dyson-Schwinger equation approach, we incorporate the quantum many-body effects caused by strong baryon-meson interactions into the equation of state for cold baryonic matter and find it stiff enough to support a maximum hyperon-star mass of $M_{\mathrm{max}} \approx 2.59 M_{\odot}$, which can explain all the observed high neutron-star masses. The resulting proton and hyperon fractions are remarkably low, thus the nucleonic and hyperonic direct Urca processes are significantly suppressed. As a result, fast cooling typically does not occur in ordinary neutron stars. △ Less

Submitted 7 March, 2026; v1 submitted 8 February, 2026; originally announced February 2026.

Comments: 12 pages, 5 figures, 1 table

Journal ref: Phys. Rev. D 113, 043050 (2026)

Spin splitting, Kondo correlation and singlet-doublet quantum phase transition in a superconductor-coupled InSb nanosheet quantum dot

Authors: Xingjun Wu, Ji-Yin Wang, Haitian Su, Han Gao, Shili Yan, Dong Pan, Jianhua Zhao, Po Zhang, H. Q. Xu

Abstract: We realize a superconductor-coupled quantum dot (QD) in an InSb nanosheet, a 2D platform promising for studies of topological superconductivity. The device consists of a superconductor-QD-superconductor junction, where a bottom bilayer gate defines the QD and allows tuning of its coupling to the superconducting leads. The QD exhibits large $g$-factors and strong spin-orbit coupling. Transport meas… ▽ More We realize a superconductor-coupled quantum dot (QD) in an InSb nanosheet, a 2D platform promising for studies of topological superconductivity. The device consists of a superconductor-QD-superconductor junction, where a bottom bilayer gate defines the QD and allows tuning of its coupling to the superconducting leads. The QD exhibits large $g$-factors and strong spin-orbit coupling. Transport measurements reveal Coulomb diamond-shaped differential conductance features with even-odd alternating sizes and pronounced conductance lines associated with the superconducting gap, confirming a few-electron, superconductor-coupled regime. At an odd electron occupation, Kondo signatures emerge, including a zero-bias peak that splits with magnetic field and is logarithmically suppressed at elevated temperatures. We further observe a doublet-singlet quantum phase transition, manifested by a clear change of Andreev bound states from crossing to anticrossing as the coupling strength increases. These results underscore the rich physics of InSb nanosheet QDs and their promise for topological quantum devices. △ Less

Submitted 6 February, 2026; originally announced February 2026.

Comments: accepted by Nano Letters

Shear subdiffusion in non-relativistic holography

Authors: Yan Liu, Zhi-Ling Wang, Xin-Meng Wu

Abstract: We study shear fluctuations in non-relativistic holographic systems coupled to torsional Newton-Cartan geometry, using asymptotically Lifshitz spacetimes in Einstein-Maxwell-dilaton gravity. We identify a universal subdiffusive shear mode characterized by the quartic dispersion relation $ω=-iD_4 k^4$, in sharp contrast to the conventional hydrodynamic diffusion. We derive this result analytically… ▽ More We study shear fluctuations in non-relativistic holographic systems coupled to torsional Newton-Cartan geometry, using asymptotically Lifshitz spacetimes in Einstein-Maxwell-dilaton gravity. We identify a universal subdiffusive shear mode characterized by the quartic dispersion relation $ω=-iD_4 k^4$, in sharp contrast to the conventional hydrodynamic diffusion. We derive this result analytically through a systematic higher-order matched asymptotic expansion connecting near-horizon and far-region solutions, and we verify it with direct numerical quasinormal mode calculations. Our numerics demonstrate that the first non-hydrodynamic mode is purely imaginary and gapped, following the dispersion relation $ω=-iω_0-i D k^2$, and that both the hydrodynamic and the first non-hydrodynamic modes pass through pole-skipping points. These results highlight Lifshitz holography as an efficient framework for anomalous transport in strongly coupled non-relativistic quantum matter. △ Less

Submitted 2 February, 2026; originally announced February 2026.

Comments: 26 pages, 2 figures, comments are welcome

Geometry-driven splitting dynamics of a triply quantized vortex in a ring-shaped condensate

Authors: Sixun Jia, Xin Wang, Xiaofeng Wu, Shuhang Wang, Bo Zhang, Bo Xiong

Abstract: We study the splitting dynamics of a triply quantized vortex (TQV) confined in a ring-shaped Bose-Einstein condensate under a weakly elliptical harmonic trap. Using full 3D simulations in cylindrical coordinates, combined with a semi-analytical energy analysis, we show that the vortex preferentially splits along the long axis of the trap, a direction that minimizes the kinetic-energy cost relative… ▽ More We study the splitting dynamics of a triply quantized vortex (TQV) confined in a ring-shaped Bose-Einstein condensate under a weakly elliptical harmonic trap. Using full 3D simulations in cylindrical coordinates, combined with a semi-analytical energy analysis, we show that the vortex preferentially splits along the long axis of the trap, a direction that minimizes the kinetic-energy cost relative to the initial TQV state. Systematic parameter scans reveal that initial quantum fluctuations increase the splitting time and suppress the transient three-core pattern observed in noise-free simulations, whereas stronger nonlinear interactions accelerate the splitting. When the trap is nearly isotropic, the unstable Bogoliubov modes are dominated by both azimuthal quantum number $l_q=3$ and $l_q=2$; this leads to a dynamical sequence where three daughter vortices first form a triangular arrangement, later evolving into a linear chain. For stronger anisotropy, geometric coupling selectively enhances the $l_q=2$ mode, making it the sole dominant channel and resulting directly in linear vortex alignment -- a clear signature of geometry-induced mode competition explained through combined energy-based and Bogoliubov stability analysis. Our results provide a quantitative picture of how trap geometry can steer the instability pathway, splitting time, and final pattern of a multiply quantized vortex, offering a route toward geometry-controlled vortex engineering. △ Less

Submitted 1 February, 2026; originally announced February 2026.

Comments: 10 pages, 6 figures

Synchronization and phase transition of two-dimensional self-rotating clock models

Authors: Xin Wu, Mingcheng Yang

Abstract: We explore possible synchronization in two-dimensional (2D) locally coupled discrete-state oscillators under thermal fluctuations, using the self-rotating $q$-state clock model as a prototype. Large-scale Monte Carlo simulations reveal that for $q \ge q_c$ (with $q_c = 5$), the system undergoes two-step Berezinskii-Kosterlitz-Thouless (BKT) transitions: first from a disordered phase to a critical… ▽ More We explore possible synchronization in two-dimensional (2D) locally coupled discrete-state oscillators under thermal fluctuations, using the self-rotating $q$-state clock model as a prototype. Large-scale Monte Carlo simulations reveal that for $q \ge q_c$ (with $q_c = 5$), the system undergoes two-step Berezinskii-Kosterlitz-Thouless (BKT) transitions: first from a disordered phase to a critical synchronized phase, and then to a spatiotemporal pattern phase. The latter includes oscillatory droplet states that survive in finite systems and a thermodynamically stable spiral wave state. Notably, the synchronized phase features algebraically decaying spatial correlations, alongside divergent coherence time, thus realizing a continuous time crystal; while it vanishes when $q < q_c$. Mean-field theory supports the existence of the synchronized phase, but predicts a lower critical value $q_c^{MF} = 4$. △ Less

Submitted 30 January, 2026; originally announced January 2026.

Comments: 7 pages, 6 figures

Electronic Origin of Density Wave Orders in a Trilayer Nickelate

Authors: Jiangang Yang, Jun Zhan, Taimin Miao, Mengwu Huo, Qichen Xu, Yinghao Li, Yuyang Xie, Bo Liang, Neng Cai, Hao Chen, Wenpei Zhu, Mingkai Xu, Shenjin Zhang, Fengfeng Zhang, Feng Yang, Zhimin Wang, Qinjun Peng, Hanqing Mao, Xintong Li, Zhihai Zhu, Guodong Liu, Zuyan Xu, Jiangping Hu, Xianxin Wu, Meng Wang , et al. (2 additional authors not shown)

Abstract: The discovery of superconductivity in Ruddlesden-Popper nickelates has established a new frontier in the study of high-temperature superconductors. However, the underlying pairing mechanism and its relationship to the material's electronic and magnetic ground states remain elusive. Since unconventional superconductivity often emerges from a complex interplay of magnetic correlations, elucidating t… ▽ More The discovery of superconductivity in Ruddlesden-Popper nickelates has established a new frontier in the study of high-temperature superconductors. However, the underlying pairing mechanism and its relationship to the material's electronic and magnetic ground states remain elusive. Since unconventional superconductivity often emerges from a complex interplay of magnetic correlations, elucidating the magnetic ground state of the nickelates at ambient pressure is crucial for understanding the emergence of superconductivity under high pressure. Here, we combine high-resolution angle-resolved photoemission spectroscopy with tight-binding model simulation to investigate the electronic structure of the representative trilayer Ruddlesden-Popper nickelate La$_4$Ni$_3$O$_{10}$. We provide the first experimental evidence of band splitting induced by interlayer coupling and further resolve the momentum-dependent density wave gap structures along all the Fermi surfaces. Our findings identify the mirror-selective Fermi surface nesting as the origin of the interlayer antiferromagnetic spin density wave and demonstrate the dominant role of Ni-3d$_{z^2}$ orbitals in the low-energy physics of La$_4$Ni$_3$O$_{10}$. These results provide a fundamental framework for understanding the magnetic interactions and high-temperature superconductivity mechanism in the Ruddlesden-Popper nickelate family. △ Less

Submitted 30 January, 2026; originally announced January 2026.

Comments: 22 pages, 5 figures

Bosonic phases across the superconductor-insulator transition in infinite-layer samarium nickelate

Authors: Menghan Liao, Heng Wang, Mingwei Yang, Chuanwu Cao, Jiayin Tang, Wenjing Xu, Xianfeng Wu, Guangdi Zhou, Haoliang Huang, Kaiwei Chen, Yuying Zhu, Peng Deng, Jianhao Chen, Zhuoyu Chen, Danfeng Li, Kai Chang, Qi-Kun Xue

Abstract: Superconductivity arises from the global phase coherence of Cooper pairs. Modulation of phase coherence leads to quantum phase transitions, serving as an important tool for studying unconventional superconductivity. Here, we demonstrate bosonic phases across the superconductor-insulator transition in infinite-layer nickelate superconducting films by the control of spatially periodic network patter… ▽ More Superconductivity arises from the global phase coherence of Cooper pairs. Modulation of phase coherence leads to quantum phase transitions, serving as an important tool for studying unconventional superconductivity. Here, we demonstrate bosonic phases across the superconductor-insulator transition in infinite-layer nickelate superconducting films by the control of spatially periodic network patterns. Magnetoresistance oscillations with a periodicity of h/2e provide direct evidence of 2e Cooper pairing in nickelates. The phase transition is predominantly driven by enhanced superconducting fluctuations, and Cooper pairs are involved in charge transport across the transition. Notably, we observe two types of anomalous metallic phases, emerging respectively at finite magnetic fields and down to zero magnetic field. They can be characterized by bosonic excitations, suggesting the dynamic roles of vortices in the ground states. Our work establishes nickelates as a key platform for investigating the rich landscape of bosonic phases controlled via the phase coherence of Cooper pairs. △ Less

Submitted 19 February, 2026; v1 submitted 27 January, 2026; originally announced January 2026.

Comments: The manuscript has been published in Phys. Rev. X https://link.aps.org/doi/10.1103/rrc1-cqdy

Superconductor-insulator transitions in infinite-layer nickelates controlled via ${operando}$ monitored reduction

Authors: Heng Wang, Haoliang Huang, Wei Lv, Xianfeng Wu, Guangdi Zhou, Zihao Nie, Yueying Li, Cui Ding, Danfeng Li, Hongtao Yuan, Qi-Kun Xue, Zhuoyu Chen

Abstract: Nickelates represent an emerging class of superconductors that demand innovative approaches for structural and electronic phase modulations. Continuous control over superconductor-insulator transition (SIT) in nickelates remains particularly challenging, hindering both fundamental understanding and potential applications. Here, we demonstrate SIT in infinite-layer nickelate superconductors utilizi… ▽ More Nickelates represent an emerging class of superconductors that demand innovative approaches for structural and electronic phase modulations. Continuous control over superconductor-insulator transition (SIT) in nickelates remains particularly challenging, hindering both fundamental understanding and potential applications. Here, we demonstrate SIT in infinite-layer nickelate superconductors utilizing multiple techniques, including an ${operando}$ monitored reduction (OMR) method. OMR enables ultrawide-range continuous modulation of the Ni 3${d}$ orbital electron occupancy from ~3${d}^7$ to ~3${d}^9$. The 3${d}$ occupancy is calibrated through systematic synchrotron X-ray absorption (XAS), combined with scanning transmission electron microscopy (STEM) annular bright field (ABF) analysis of oxygen atoms. SIT is further modulated via ionic liquid gating and magnetic field. Strikingly different from cuprates, our Nernst effect measurements show that pairing initiates at the onset of the resistive drop. The subsequent emergence of the Meissner effect at zero resistance marks the establishment of global phase coherence. Angle-dependent magnetotransport within the transition temperature regime indicates a mixture of two-dimensional (2D) and three-dimensional (3D) superconducting characters, suggesting the observed SIT deviates from the canonical 2D model. Our results provide a unique perspective on the interplay of structural and electronic phase transitions in the infinite-layer nickelates across the oxygen content-magnetic field-temperature parameter space. △ Less

Submitted 20 January, 2026; originally announced January 2026.

Comments: 9 pages, 5 figures

Ir3Ge20: A 3n-Connected Cloverleaf-Shaped Supercluster

Authors: Xue Wu, Wen-Shuai Dai, Lulu Li, Fangying Hao, Hong-Guang Xu, Wei-Jun Zheng, Jijun Zhao

Abstract: Group 14 Zintl clusters are promising molecular building blocks for nanoscale architecture. Endohedral variants, which encapsulate d/f-block metals within p-block semimetal cages, provide insights into intermetallic bonding and compound formation. In this study, experimental photoelectron spectroscopy and first-principles calculations were used to investigate the Ir-doped germanium cluster species… ▽ More Group 14 Zintl clusters are promising molecular building blocks for nanoscale architecture. Endohedral variants, which encapsulate d/f-block metals within p-block semimetal cages, provide insights into intermetallic bonding and compound formation. In this study, experimental photoelectron spectroscopy and first-principles calculations were used to investigate the Ir-doped germanium cluster species. A new C2v symmetric building block, IrGe12, was identified, serving as the basis for designing the supercluster Ir3Ge20 with a cloverleaf-shaped, D3h symmetric architecture. This structure consists of three interconnected aromatic IrGe12 units linked by Ge-Ge sigma bonds, forming shielding cones. Ir3Ge20 follows the 5n rule with 100 valence electrons, featuring a core-Ir3 unit with a d10 closed-shell configuration sharing electrons with the Ge20 skeleton. The stability, chemical bonding, and aromaticity of Ir3Ge20 were confirmed, demonstrating a novel approach to precise atom manipulation in cluster-based materials and devices. △ Less

Submitted 6 January, 2026; originally announced January 2026.

Common sublattice-pure van Hove singularities in the kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs)

Authors: Yujie Lan, Yuhao Lei, Congcong Le, Brenden R. Ortiz, Nicholas C. Plumb, Milan Radovic, Xianxin Wu, Ming Shi, Stephen D. Wilson, Yong Hu

Abstract: Kagome materials offer a versatile platform for exploring correlated and topological quantum states, where van Hove singularities (VHSs) play a pivotal role in driving electronic instabilities, exhibiting distinct behaviors depending on electron filling and interaction settings. In the recently discovered kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs), unconventional… ▽ More Kagome materials offer a versatile platform for exploring correlated and topological quantum states, where van Hove singularities (VHSs) play a pivotal role in driving electronic instabilities, exhibiting distinct behaviors depending on electron filling and interaction settings. In the recently discovered kagome superconductors $\textit{A}$V$_{3}$Sb$_{5}$ ($\textit{A}$ = K, Rb, Cs), unconventional charge density wave order, superconductivity, and electronic chirality emerge, yet the nature of VHSs near the Fermi level ($\textit{E}$$_{F}$) and their connection to these exotic orders remain elusive. Here, using high-resolution polarization-dependent angle-resolved photoemission spectroscopy, we uncover a universal electronic structure across $\textit{A}$V$_{3}$Sb$_{5}$ that is distinct from density-functional theory predictions that show noticeable discrepancies. We identify multiple common sublattice-pure VHSs near $\textit{E}$$_{F}$, arising from strong V-$\textit{d}$/Sb-$\textit{p}$ hybridization, which significantly promote bond-order fluctuations and likely drive the observed charge density wave order. These findings provide direct spectroscopic evidence for hybridization-driven VHS formation in kagome metals and establish a unified framework for understanding the intertwined electronic instabilities in $\textit{A}$V$_{3}$Sb$_{5}$. △ Less

Submitted 4 January, 2026; originally announced January 2026.

Journal ref: Phys. Rev. Lett. 136, 016401 (2026)

Time-Reversal Symmetry Breaking Superconducting State and Collective Modes in Kagome Superconductors

Authors: Xinloong Han, Jun Zhan, Jiangping Hu, Fu-chun Zhang, Xianxin Wu

Abstract: We comprehensively study the unconventional pairing and collective modes in the multiband kagome superconductors AV$_3$Sb$_5$ (A=$\mathrm{K},\mathrm{Cs},\mathrm{Rb}$). By solving gap equations at zero temperature, we identify a transition from normal $s++/s\pm$-wave pairing to time-reversal symmetry (TRS) breaking pairing with a variation of inter-pocket interactions or density of states. This TRS… ▽ More We comprehensively study the unconventional pairing and collective modes in the multiband kagome superconductors AV$_3$Sb$_5$ (A=$\mathrm{K},\mathrm{Cs},\mathrm{Rb}$). By solving gap equations at zero temperature, we identify a transition from normal $s++/s\pm$-wave pairing to time-reversal symmetry (TRS) breaking pairing with a variation of inter-pocket interactions or density of states. This TRS breaking pairing originates from the superconducting phase frustration of different Fermi pockets and can account for experimental TRS breaking signal in kagome superconductors. Moreover, we investigate collective modes, including the Higgs, Leggett, and Bogoloubov-Anderson-Goldstone modes, arising from fluctuations of the amplitude, relative phase, and overall phase of the superconducting order parameters, respectively. Remarkably, due to the presence of multibands, one branch of the Leggett modes becomes nearly massless near the TRS breaking transition, providing a compelling smoking-gun signature of TRS-breaking superconductivity, in clear contrast to TRS-breaking charge orders. Our results elucidate the rich superconducting physics and its associated collective modes in kagome metals, and suggest feasible experimental detection of TRS breaking pairing. △ Less

Submitted 31 December, 2025; originally announced December 2025.

Comments: 10 pages, 4 figures

Lattice-Entangled Density Wave Instability and Nonthermal Melting in La$_4$Ni$_3$O$_{10}$

Authors: Chen Zhang, Lixing Chen, Qi-Yi Wu, Congcong Le, Xianxin Wu, Hao Liu, Bo Chen, Ying Zhou, Zhong-Tuo Fu, Chun-Hui Lv, Zi-Jie Xu, Hai-Long Deng, Enkang Zhang, Yinghao Zhu, H. Y. Liu, Yu-Xia Duan, Jun Zhao, Jian-Qiao Meng

Abstract: The recent discovery of high-temperature superconductivity in pressurized nickelates has renewed interest in the broken-symmetry states of their ambient-pressure parent phases, where a density-wave (DW) order emerges and competes with superconductivity, but its microscopic origin remains unresolved. Using ultrafast optical spectroscopy, we track quasiparticle relaxation dynamics across the DW tran… ▽ More The recent discovery of high-temperature superconductivity in pressurized nickelates has renewed interest in the broken-symmetry states of their ambient-pressure parent phases, where a density-wave (DW) order emerges and competes with superconductivity, but its microscopic origin remains unresolved. Using ultrafast optical spectroscopy, we track quasiparticle relaxation dynamics across the DW transition at $T_{\rm DW} \approx$ 136 K in trilayer nickelate La$_4$Ni$_3$O$_{10}$ single crystals, revealing the opening of an energy gap of $\sim$ 52 meV. Multiple coherent phonons, including $A_g$ modes near 3.88, 5.28, and 2.09 THz, display pronounced mode-selective anomalies across the transition, demonstrating that the DW is coupled with lattice degree of freedom stabilized through electron-phonon coupling. At higher excitation densities, the DW is nonthermally suppressed, producing a temperature-fluence phase diagram that parallels pressure-tuned behavior. These results establish the DW in La$_4$Ni$_3$O$_{10}$ as a lattice-entangled instability involving multiple phonon modes, and highlight ultrafast optical excitation as a powerful tool to manipulate competing orders in nickelates. △ Less

Submitted 27 December, 2025; originally announced December 2025.

Comments: 5 pages, 4 figures

Channel-last gate-all-around nanosheet oxide semiconductor transistors

Authors: Fabia F. Athena, Xiangjin Wu, Nathaniel S. Safron, Amy Siobhan McKeown-Green, Mauro Dossena, Jack C. Evans, Jonathan Hartanto, Yukio Cho, Donglai Zhong, Tara Peña, Paweł Czaja, Parivash Moradifar, Paul C. McIntyre, Mathieu Luisier, Yi Cui, Jennifer A. Dionne, Greg Pitner, Iuliana P. Radu, Eric Pop, Alberto Salleo, H. -S. Philip Wong

Abstract: As we move beyond the era of transistor miniaturization, back-end-of-line-compatible transistors that can be stacked monolithically in the third dimension promise improved performance for low-power electronics. In advanced transistor architectures, such as gate-all-around nanosheets, the conventional channel-first process involves depositing dielectrics directly onto the channel. Atomic layer depo… ▽ More As we move beyond the era of transistor miniaturization, back-end-of-line-compatible transistors that can be stacked monolithically in the third dimension promise improved performance for low-power electronics. In advanced transistor architectures, such as gate-all-around nanosheets, the conventional channel-first process involves depositing dielectrics directly onto the channel. Atomic layer deposition of gate dielectrics on back-end-of-line compatible channel materials, such as amorphous oxide semiconductors, can induce defects or cause structural modifications that degrade electrical performance. While post-deposition annealing can partially repair this damage, it often degrades other device metrics. We report a novel channel-last concept that prevents such damage. Channel-last gate-all-around self-aligned transistors with amorphous oxide-semiconductor channels exhibit high on-state current ($>$ 1 mA/$μ$m) and low subthreshold swing (minimum of 63 mV/dec) without the need for post-deposition processing. This approach offers a general, scalable pathway for transistors with atomic layer deposited channel materials, enabling the future of low-power three-dimensional electronics. △ Less

Submitted 24 December, 2025; originally announced December 2025.

Comparative Raman study of Ruddlesden-Popper nickelates and the monolayer-trilayer polymorph

Authors: Vignesh Sundaramurthy, Abhi Suthar, Pascal Puphal, Congcong Le, Yuhao Gu, Hasan Yilmaz, Pablo Sosa-Lizama, Peter A. van Aken, Y. Eren Suyolcu, Masahiko Isobe, Andreas P. Schnyder, Xianxin Wu, Matteo Minola, Bernhard Keimer, Matthias Hepting

Abstract: Ruddlesden-Popper (RP) nickelates have attracted intense interest following the discovery of superconductivity in several members of the series, including bilayer (BL) La$_3$Ni$_2$O$_7$, trilayer (TL) La$_4$Ni$_3$O$_{10}$, and structural polymorphs composed of monolayer-bilayer or monolayer-trilayer (ML-TL) units. However, an inherent propensity of the RP series to form intergrown phases during si… ▽ More Ruddlesden-Popper (RP) nickelates have attracted intense interest following the discovery of superconductivity in several members of the series, including bilayer (BL) La$_3$Ni$_2$O$_7$, trilayer (TL) La$_4$Ni$_3$O$_{10}$, and structural polymorphs composed of monolayer-bilayer or monolayer-trilayer (ML-TL) units. However, an inherent propensity of the RP series to form intergrown phases during single-crystal synthesis, together with spatial variations in oxygen stoichiometry, has complicated the determination of their intrinsic material properties. As a consequence, conflicting reports have emerged on both their electronic phase transitions and lattice dynamics. In this work, we perform a comparative study of the phononic and electronic Raman responses of high-quality ML-TL single crystals and contrast them with those of other RP nickelates, using samples with optimized oxygen content. We establish several Raman spectral features that enable unambiguous phase identification across the series. Moreover, we uncover characteristics in the phononic and electronic Raman response of ML-TL that are not reflected in the pure ML and TL compounds. We attribute these differences to a distinctive electronic structure arising from self-doping and confinement effects induced by the ML unit within the ML-TL lattice architecture. △ Less

Submitted 19 December, 2025; originally announced December 2025.

Comments: 12 pages, 5 figures

Mirror-Selective Quasiparticle Interference in Bilayer Nickelate Superconductor

Authors: Zhongyi Zhang, Jun Zhan, Congcong Le, Hoi Chun Po, Jiangping Hu, Xianxin Wu

Abstract: The recent discovery of high-temperature superconductivity in both bulk and thin-film bilayer nickelates has garnered significant attention. In this study, inspired by recent STM experiments on thin films, we investigate the quasiparticle interference (QPI) characteristics of bilayer nickelates in both normal and superconducting states to identify their Fermiology and pairing symmetry. We demonstr… ▽ More The recent discovery of high-temperature superconductivity in both bulk and thin-film bilayer nickelates has garnered significant attention. In this study, inspired by recent STM experiments on thin films, we investigate the quasiparticle interference (QPI) characteristics of bilayer nickelates in both normal and superconducting states to identify their Fermiology and pairing symmetry. We demonstrate that the mirror symmetry inherent in the bilayer structure induces mirror-selective quasiparticle scattering by establishing selection rules based on the mirror properties of impurities and the mirror eigenvalues of electronic wavefunctions. This mirror-selective scattering allows for the differentiation of distinct Fermiologies, as QPI patterns vary markedly between scenarios with and without the $d_{z^2}$-bonding Fermi surface (FS). Furthermore, it enables the separate detection of sign changes in superconducting gaps both within the same FS and between different FSs. Crucially, if the mirror-symmetry-enforced selection rules are ignored, the QPI response of an $s_\pm$-wave state can masquerade as that of a conventional $s$-wave state, leading to a misidentification of the pairing symmetry. When combined with field-dependent and reference QPI measurements, this approach facilitates the precise determination of pairing symmetry, even in the presence of FS-dependent gaps and gap anisotropy. Additionally, we discuss practical considerations for STM measurements to effectively identify the pairing symmetry. Our findings demonstrate that mirror-selective QPI is a powerful tool for distinguishing between different Fermiologies and pairing states, which is helpful in pinning down pairing symmetry and revealing the pairing mechanism in bilayer nickelates. △ Less

Submitted 16 December, 2025; originally announced December 2025.

Comments: 10 pages, 5 figures

Probing the Crossover between Dynamical Phases with Local Correlations in a Rydberg Atom Array

Authors: Xiaofeng Wu, Xin Wang, Sixun Jia, Bo Xiong

Abstract: The experimental detection of non-equilibrium quantum criticality remains a challenge, as traditional signatures like dynamical quantum phase transitions rely on hard-to-measure global properties. Here, we demonstrate that local connected correlation functions provide a superior, practical means to directly probe the dynamics of magnetic order in a quenched Rydberg atom array. Using a Magnus expan… ▽ More The experimental detection of non-equilibrium quantum criticality remains a challenge, as traditional signatures like dynamical quantum phase transitions rely on hard-to-measure global properties. Here, we demonstrate that local connected correlation functions provide a superior, practical means to directly probe the dynamics of magnetic order in a quenched Rydberg atom array. Using a Magnus expansion formalism, we derive analytic expressions for these correlations that capture a smooth crossover from antiferromagnetic to ferromagnetic dominance. Our analytic results, which reveal the critical parameter relationship $U_{c}(δ)$, are validated against exact numerical simulations and exhibit robustness to finite-size effects. By shifting the focus from global singularities to local correlations, our protocol establishes a direct and feasible path to observe the rich critical dynamics in scalable quantum simulators. △ Less

Submitted 14 December, 2025; originally announced December 2025.

Comments: 6+9 pages, 4+2 figures

Switchable half-quantum flux states in a ring of the kagome superconductor CsV$_3$Sb$_5$

Authors: Shuo Wang, Ilaria Maccari, Xilin Feng, Ze-Nan Wu, Jia-Peng Peng, Kam Tuen Law, Y. X. Zhao, Andras Szabo, Andreas Schnyder, Ning Kang, Xiao-Song Wu, Jingchao Liu, Xuewen Fu, Mark H. Fischer, Manfred Sigrist, Dapeng Yu, Ben-Chuan Lin

Abstract: Magnetic flux quantization in units of $Φ_0 = h/2e$ is a defining feature of superconductivity, rooted in the charge-2e nature of Cooper pairs. In a ring geometry, the flux quantization leads to oscillations in the critical temperature with magnetic flux, known as the Little-Parks effect. While the maximal critical temperature is conventionally at zero flux, departures from this rule, for instance… ▽ More Magnetic flux quantization in units of $Φ_0 = h/2e$ is a defining feature of superconductivity, rooted in the charge-2e nature of Cooper pairs. In a ring geometry, the flux quantization leads to oscillations in the critical temperature with magnetic flux, known as the Little-Parks effect. While the maximal critical temperature is conventionally at zero flux, departures from this rule, for instance shifts by a half-quantum flux $Φ_0/2$, clearly signal unconventional superconducting states and require sign-changing order parameters. Historically, such $π$-phase shifts in Little-Parks oscillations have been found in tricrystals or engineered ring structures that intentionally incorporate a $π$-phase shift. Here we report the discovery of switchable half-quantum flux states in rings made from single crystals of the kagome superconductor CsV$_3$Sb$_5$. We observe Little-Parks oscillations with a $π$-phase shift at zero bias current, which can be reversibly tuned to conventional Little-Parks oscillations upon applying a bias current. Between the $π$-phase and 0-phase regimes, $h/4e$ periodic oscillations appear. Our observations suggest unconventional pairing, potentially in the form of a multicomponent order parameter in the kagome superconductor CsV$_3$Sb$_5$, and reveal an electrically tunable landscape of competing superconducting condensates and fractional flux states. △ Less

Submitted 16 December, 2025; v1 submitted 10 December, 2025; originally announced December 2025.

Comments: 49 pages, 23 figures

Spectrally-selective dynamic radiative thermoregulation via phase engineering

Authors: Qizhang Li, Yuanke Chen, Zhuang Luo, Chenxi Sui, Xubing Wu, Ronghui Wu, Qingsong Fan, Ching-Tai Fu, Pei-Jan Hung, Gangbin Yan, Genesis Higueros, Ting-Hsuan Chen, Po-Chun Hsu

Abstract: Maintaining comfortable temperatures for buildings, humans, and devices consumes a substantial portion of global energy, underscoring the urgent need for energy-efficient thermoregulation technologies. Dynamic radiative thermal emitters that can switch between passive cooling and heating modes offer a promising solution, but most existing devices exhibit broadband optical responses, resulting in u… ▽ More Maintaining comfortable temperatures for buildings, humans, and devices consumes a substantial portion of global energy, underscoring the urgent need for energy-efficient thermoregulation technologies. Dynamic radiative thermal emitters that can switch between passive cooling and heating modes offer a promising solution, but most existing devices exhibit broadband optical responses, resulting in unwanted parasitic heat exchange and limited performance. Here, we introduce an elegant strategy that uses a dielectric cap to transform broadband metal-insulator transition (MIT) materials into spectrally selective dynamic emitters. This design creates a highly tunable Fabry-Perot cavity, enabling a tailored thermal emission spectrum by engineering the reflected-wave phase profile. Our Fresnel-formalism-based phasor diagram analysis reveals two key routes for realizing high spectral selectivity: a high-index dielectric cap and a low-loss metallic MIT state, which are further validated by Bayesian optimization. Following this principle, we demonstrated a wide-angle spectrally-selective thermoregulator operating in the atmospheric transparency window (8-13 um), where the thermal emittance can be electrically tuned from about 0.2 to 0.9 through reversible copper electrodeposition on a germanium cavity. Furthermore, this strategy can be extended to multispectral electrochromic windows, enabling switching between solar heating and spectrally-selective radiative cooling. Our work establishes a versatile and generalizable paradigm for spectral engineering of dynamic thermal emitters, opening opportunities in energy-efficient buildings, wearable thermal comfort, spacecraft thermoregulation, and multispectral camouflage. △ Less

Submitted 4 December, 2025; originally announced December 2025.

Spin-flop driven interfacial tunneling magnetoresistance in an antiferromagnetic tunnel junction

Authors: Xiaolin Ren, Ruizi Liu, Yiyang Zhang, Yuting Liu, Xuezhao Wu, Kun Qian, Kenji Watanabe, Takashi Taniguchi, Qiming Shao

Abstract: The utilization of two-dimensional (2D) materials in magnetic tunnel junctions (MTJs) has shown excellent performance and rich physics. As for 2D antiferromagnets, the magnetic moments in different layers respond asynchronously and can be configured at various states under different magnetic fields, showing the possibility of efficient magnetic and electrical tunability. In this report, A-type ant… ▽ More The utilization of two-dimensional (2D) materials in magnetic tunnel junctions (MTJs) has shown excellent performance and rich physics. As for 2D antiferromagnets, the magnetic moments in different layers respond asynchronously and can be configured at various states under different magnetic fields, showing the possibility of efficient magnetic and electrical tunability. In this report, A-type antiferromagnetic (AFM) material (Fe0.5Co0.5)5GeTe2 (FCGT) works as electrodes to realize full van der Waals magnetic tunnel junctions. Owing to the interfacial effect, the even-layer FCGT, although with zero net magnetization, exhibits spin selectivity in MTJ architecture contributing to a tunneling magnetoresistance (TMR) reaching about 25% at a low operating current 1 nA at 100 K and persists near room temperature. Due to the surface spin-flop (SSF) effect in antiferromagnetic FCGT, the alternation flexibility between the volatile and nonvolatile memory behavior is achieved. The interfacial TMR can be tuned efficiently in amplitude and even sign under different bias currents and temperatures. These findings show precise magnetoelectric manipulation in MTJs based on 2D antiferromagnets and highlight the promise of 2D antiferromagnets for spintronic devices. △ Less

Submitted 3 December, 2025; originally announced December 2025.

Emergent Chiral Spin Crystal Phase in (111) SrRuO3 Thin Films

Authors: Zhaoqing Ding, Yongjie Xie, Xuejiao Chen, Sheng Wang, Zhen Wang, Zeguo Lin, Enling Wang, Xiaofeng Wu, Mingyu Yang, Yuelong Xiong, Meng Meng, Fang Yang, Jiandi Zhang, Xianggang Qiu, XIaoran Liu, Jiandong Guo

Abstract: Perovskite ruthenates are fascinating playgrounds for exploring topological spin textures, but generally rely on extrinsic mechanisms to trigger the noncoplanar states. Here we report the discovery of an emergent chiral spin crystal phase in (111) SrRuO3 epitaxial films, characterized by a significant topological Hall effect and noncoplanar spin arrangements with different propagation vectors alon… ▽ More Perovskite ruthenates are fascinating playgrounds for exploring topological spin textures, but generally rely on extrinsic mechanisms to trigger the noncoplanar states. Here we report the discovery of an emergent chiral spin crystal phase in (111) SrRuO3 epitaxial films, characterized by a significant topological Hall effect and noncoplanar spin arrangements with different propagation vectors along two orthogonal directions. Instead of driven by the enhanced Dzyaloshinskii-Moriya interaction due to broken inversion symmetry at heterointerfaces, this emergent state arises intrinsically from the interplay of dipolar interactions and magnetic frustration, leading to the stabilization of topological phases in much thicker films. These findings open a new pathway for creating and controlling the topological spin states in perovskites, with broad implications for spintronic device design. △ Less

Submitted 2 December, 2025; originally announced December 2025.

Synthetic Spatiotemporal Plasmonic Vortices On Chip

Authors: Qian Chen, Shuoshuo Zhang, Guoyu Xian, Haoqiang Hu, Xiaohua Wu, Xiaofei Wu, Jer-Shing Huang, Chen-Bin Huang, Jin-Hui Zhong, Yuquan Zhang, Xiaocong Yuan, Changjun Min, Yanan Dai

Abstract: Spatiotemporal vortices are polychromatic modes that intertwine orbital angular momentum (OAM) in space and time. Here we introduce a new class of such vortices, spatiotemporal plasmonic vortices (STPVs), carrying nontrivial topological spin textures. They are generated by chronotopic interference of temporally delayed plasmonic eigen-vortices, where a $π$-phase dislocation in the space-frequency… ▽ More Spatiotemporal vortices are polychromatic modes that intertwine orbital angular momentum (OAM) in space and time. Here we introduce a new class of such vortices, spatiotemporal plasmonic vortices (STPVs), carrying nontrivial topological spin textures. They are generated by chronotopic interference of temporally delayed plasmonic eigen-vortices, where a $π$-phase dislocation in the space-frequency domain maps into a 2$π$ spiraling phase in space-time, with the resulting focus-defocus dynamics emulate U(1) gauge transitions. Using interferometric time-resolved photoemission electron microscopy (ITR-PEEM), we directly image their nanometer-attosecond (nano-atto) evolution and control vortex number and position. Quantum-path analysis of coherent two-photon photoemission (2PP) processes reveals the nonlinear plasmonic polarization fields and angular-momentum conservation, establishing STPVs as a platform for probing spatiotemporally structured quantum matter. △ Less

Submitted 20 November, 2025; originally announced November 2025.

Strongly Electric Field Dependent Conductivity in Quantum Dot Solids

Authors: Morteza Shokrani, Xinlu Wu, Ebbo Krahmer, Martijn Kemerink

Abstract: Charge transport in QD solids is typically understood as thermally activated tunneling or hopping between states that are localized on individual QDs. Here, we show that the slow relaxation that is associated with the disorder-broadened density of (localized) states leads to a strong electric field F dependence of the charge carrier mobility. We interpret the results in terms of an increased effec… ▽ More Charge transport in QD solids is typically understood as thermally activated tunneling or hopping between states that are localized on individual QDs. Here, we show that the slow relaxation that is associated with the disorder-broadened density of (localized) states leads to a strong electric field F dependence of the charge carrier mobility. We interpret the results in terms of an increased effective electronic temperature T_eff that exceeds that of the lattice. We use a heat balance model to derive an analytical expression for T_eff (F) that is similar to, and puts a physical basis under the phenomenological expression proposed by Marianer and Shklovskii [Phys. Rev. B 46, 13100 (1992)]. We apply this model to analyze the field- and temperature-dependent conductivity in ZnO QDs with varying ligand length and depletion shell thickness and find (effective) localization lengths ranging from 2 to 5 nm. Both experimental and analytical results compare favorably to numerical simulations by kinetic Monte Carlo. Due to the large value of the effective localization length, the field dependence already becomes relevant at modest fields around 1-10 V/micron, that are typical for operational conditions of photovoltaic and light emitting devices based on quantum dot solids. △ Less

Submitted 18 November, 2025; originally announced November 2025.

Comments: -

Dynamic Permeability in Metastable Droplet Interfacial Bilayers

Authors: Nivedina A. Sarma, David A. King, Xuefei Wu, Brett A. Helms, Paul D. Ashby, Thomas P. Russell, Ahmad K. Omar

Abstract: Membrane pores are implicated in several critical functions, including cell fusion and the transport of signaling molecules for intercellular communication. However, these structural features are often difficult to probe directly. Droplet interfacial bilayers offer a synthetic platform to study such membrane properties. We develop a theory that links size-selective transport across a metastable me… ▽ More Membrane pores are implicated in several critical functions, including cell fusion and the transport of signaling molecules for intercellular communication. However, these structural features are often difficult to probe directly. Droplet interfacial bilayers offer a synthetic platform to study such membrane properties. We develop a theory that links size-selective transport across a metastable membrane with its transient structural properties. The central quantity of our theory is a dynamic permeability that depends on the mechanism of pore growth, which controls the transient distribution of pore sizes in the membrane. We present a mechanical perspective to derive pore growth dynamics and the resulting size distribution for growth \textit{via} Ostwald ripening and discuss how these dynamics compare to other growth mechanisms such as coalescence and growth through surfactant desorption. We find scaling relations between the transported particle size, the pore growth rate, and the time for a given fraction of particles to cross the membrane, from which one may deduce the dominant mechanism of pore growth, as well as material properties and structural features of the membrane. Finally, we suggest experiments using droplet interfacial bilayers to validate our theoretical predictions. △ Less

Submitted 12 November, 2025; originally announced November 2025.

Fine-Tuning Vision-Language Models for Multimodal Polymer Property Prediction

Authors: An Vuong, Minh-Hao Van, Prateek Verma, Chen Zhao, Xintao Wu

Abstract: Vision-Language Models (VLMs) have shown strong performance in tasks like visual question answering and multimodal text generation, but their effectiveness in scientific domains such as materials science remains limited. While some machine learning methods have addressed specific challenges in this field, there is still a lack of foundation models designed for broad tasks like polymer property pre… ▽ More Vision-Language Models (VLMs) have shown strong performance in tasks like visual question answering and multimodal text generation, but their effectiveness in scientific domains such as materials science remains limited. While some machine learning methods have addressed specific challenges in this field, there is still a lack of foundation models designed for broad tasks like polymer property prediction using multimodal data. In this work, we present a multimodal polymer dataset to fine-tune VLMs through instruction-tuning pairs and assess the impact of multimodality on prediction performance. Our fine-tuned models, using LoRA, outperform unimodal and baseline approaches, demonstrating the benefits of multimodal learning. Additionally, this approach reduces the need to train separate models for different properties, lowering deployment and maintenance costs. △ Less

Submitted 4 November, 2025; originally announced November 2025.

Scaling of the disorder operator at (3+1)D O(3) quantum criticality

Authors: Xuyang Liang, Xiao-Chuan Wu, Zenan Liu, Zhe Wang, Zheng Yan, Dao-Xin Yao

Abstract: The disorder operator, as an easily measured non-local observable, displays great potential in detecting intrinsic information of field theories. It has been systematically studied in 1d and 2d quantum systems, while the knowledge of 3d is still limited. The disorder operator associated with U(1) global symmetry exhibits rich geometric dependence on the shape of the spatial region at a quantum cri… ▽ More The disorder operator, as an easily measured non-local observable, displays great potential in detecting intrinsic information of field theories. It has been systematically studied in 1d and 2d quantum systems, while the knowledge of 3d is still limited. The disorder operator associated with U(1) global symmetry exhibits rich geometric dependence on the shape of the spatial region at a quantum critical point, meanwhile, (3+1)D is the upper critical dimension for O(N) criticalities, both of which pose a challenge for exploring the disorder operator in high dimensions. In this work, we investigate the scaling behaviors of disorder operators in (3+1)D O(3) models through large-scale quantum Monte Carlo simulation combined with theoretical analysis. The universal contributions, such as the current central charge, have been revealed in our calculation, which establishes a concrete link between lattice simulations and continuum field theory. This work opens new avenues for experimental and numerical exploration of universal properties at quantum critical points in (3+1)D models. △ Less

Submitted 29 October, 2025; originally announced October 2025.

Comments: 11 pages, 6 figures

All-Altermagnetic Tunnel Junction of RuO2/NiF2/RuO2

Authors: Long Zhang, Guangxin Ni, Xuehao Wu, Guoying Gao

Abstract: Emerging altermagnets with zero net magnetic moment and moment-dependent spin splitting offer a promising avenue for antiferromagnetic spintronic devices, yet their integration into magnetic tunnel junctions has been hindered by reliance on ferromagnetic electrodes (introducing stray fields) or by limited functionality (non-tunable magnetoresistance without spin filtering). Here, we propose an all… ▽ More Emerging altermagnets with zero net magnetic moment and moment-dependent spin splitting offer a promising avenue for antiferromagnetic spintronic devices, yet their integration into magnetic tunnel junctions has been hindered by reliance on ferromagnetic electrodes (introducing stray fields) or by limited functionality (non-tunable magnetoresistance without spin filtering). Here, we propose an all-altermagnetic tunnel junction (AAMTJ) paradigm composed exclusively of altermagnets, exemplified by experimentally feasible RuO2/NiF2/RuO2. By introducing an altermagnetic NiF2 barrier, the achieved tunneling magnetoresistances of 11,704%, 2,496% and 1,892% for RuO2/NiF2/RuO2 are much higher than that of 221% for RuO2/TiO2/RuO2 with a nonmagnetic TiO2 barrier. High spin filtering efficiencies of ~90% are also obtained. This architecture unlocks multistate high magnetoresistance and spin filtering via magnetization control of the electrodes and barrier, stemming from their synergistic and antagonistic alignments of momentum-dependent altermagnetic spin-splitting. Importantly, high tunneling magnetoresistances are still achieved in the AAMTJ with TiO2 spacer of RuO2/TiO2/NiF2/TiO2/RuO2. Our AAMTJ inherently exhibits low consumption and zero stray field, with nonrelativistic spin splitting and vanishing magnetic moment, combining the advantages of both ferromagnetic and antiferromagnetic tunnel junctions. This AAMTJ paradigm opens an interesting avenue within the area of high-performance altermagnet-based tunnel junctions. △ Less

Submitted 13 March, 2026; v1 submitted 27 October, 2025; originally announced October 2025.

Comments: 21 pages, 6 figures, 2 tables

Journal ref: Chinese Physics Letters, 2026, 43(4): 040711

Sliding Disassembly of van der Waals Heterostructures

Authors: Jordan Pack, Karl V. Falb, Sanat Ghosh, Xuehao Wu, Keng Tou Chu, Florie Mesple, Ellis Thompson, Zhuquan Zhang, Carolin Gold, Kenji Watanabe, Takashi Taniguchi, Dmitri N. Basov, A. N. Pasupathy, Matthew Yankowitz, Cory R. Dean, Aravind Devarakonda

Abstract: Many recent advances in our understanding of two-dimensional (2D) electron systems stem from van der Waals (vdW) heterostructures. The assembly process relies on the weak bonding across interfaces between layered vdW compounds, making it possible to construct exceptionally clean heterostructures from chemically and structurally distinct materials - a challenging task for traditional thin-film grow… ▽ More Many recent advances in our understanding of two-dimensional (2D) electron systems stem from van der Waals (vdW) heterostructures. The assembly process relies on the weak bonding across interfaces between layered vdW compounds, making it possible to construct exceptionally clean heterostructures from chemically and structurally distinct materials - a challenging task for traditional thin-film growth techniques. Here we demonstrate an additional, dynamic degree of freedom afforded by vdW interfaces, wherein we use microstructured polymer stamps to disassemble and reconfigure vdW heterostructures by sliding. We apply this technique to alter the dielectric environment of monolayer graphene, perform scanning tunneling microscopy on semiconducting and air-sensitive monolayers, and manipulate strain-sensitive moiré materials. Together these demonstrations suggest a new paradigm for assembling and dynamically modifying van der Waals heterostructures, with the potential to reveal new insights into 2D electron systems. △ Less

Submitted 21 October, 2025; originally announced October 2025.

Comments: 16 pages, 9 figures, 3 supplemental videos

Facet Specific Electron Conduction in Pentavalent (W5+) WO3 Drives Superior Photocatalytic CO 2 Reduction in (002) Plane

Authors: Muhammad Rizwan Kamal, Mohammad Z. Rahman, Amil Aligayev, Min Liu, Li Zhong, Pengfei Xia, Yueheng Li, Yue Ruan, Xia Xiang, Pir Muhammad Ismail, Qaisar Alam, Ahmed Ismail, Muhammad Zahid, Xiaoqiang Wu, Abdullah N. Alodhayb, Qing Huang, Raj Wali Khan, Fazal Raziq, Sharafat Ali, Liang Qiao

Abstract: This article reports a concept of heat-induced topological modifications of non-layered WO 3 followed by successful synthesis of oxygen-vacant more-porous nanosheets with exposed active (002) facet. Experimental measurements and Density Functional Theory (DFT) calculations have revealed that the photoexcited electrons are found to accumulate preferentially on (002) facet to yield enhanced electron… ▽ More This article reports a concept of heat-induced topological modifications of non-layered WO 3 followed by successful synthesis of oxygen-vacant more-porous nanosheets with exposed active (002) facet. Experimental measurements and Density Functional Theory (DFT) calculations have revealed that the photoexcited electrons are found to accumulate preferentially on (002) facet to yield enhanced electron conduction, and consequently, strengthen the reduction potential as active catalytic sites for photocatalytic CO2 reduction. Owing to these beneficial properties, the more-porous nanosheets of WO 3 with (002) facet have exhibited superior performance than that of less-porous nanosheets of WO3 with (220) facet and bulk WO3 with (205) facet. This study therefore provides a new understanding of regulating physical, optical, and electronic properties through intricate atomic structure modulation of WO3, and may find widespread application in optoelectronics, sensors, and energy conversion. △ Less

Submitted 17 October, 2025; originally announced October 2025.

Phase-sensitive evidence for 2x2 pair density wave in a kagome superconductor

Authors: Xiao-Yu Yan, Guowei Liu, Hanbin Deng, Xitong Xu, Haiyang Ma, Hailang Qin, Jun-Yi Zhang, Yuanyuan Zhao, Haitian Zhao, Zhe Qu, Yigui Zhong, Kozo Okazaki, Xiquan Zheng, Yingying Peng, Zurab Guguchia, X. X. Wu, Qianghua Wang, X-H Fan, Wei Song, M-W Gao, Hendrik Hohmann, Matteo Durrnagel, Ronny Thomale, Jia-Xin Yin

Abstract: The pair-density-wave (PDW) exhibits periodic amplitude and sign modulations of the superconducting order parameter. Such a pairing state has been proposed to be sensitive to nonmagnetic scattering. In this work, we observe the nonmagnetic PDW-breaking effect in a kagome superconductor, using scanning tunneling microscopy. We observe 2x2 PDW induced by the coupling between charge order and superco… ▽ More The pair-density-wave (PDW) exhibits periodic amplitude and sign modulations of the superconducting order parameter. Such a pairing state has been proposed to be sensitive to nonmagnetic scattering. In this work, we observe the nonmagnetic PDW-breaking effect in a kagome superconductor, using scanning tunneling microscopy. We observe 2x2 PDW induced by the coupling between charge order and superconductivity. The global PDW is substantially suppressed upon doping the kagome lattice with dilute isovalent nonmagnetic impurities, whereas the charge order and uniform superconductivity remain robust. Spatial correlation analysis further confirms that PDW is distinctly suppressed near dopants. We attribute the PDW suppression to a nonmagnetic PDW breaking effect, arising from phase sign modulation of PDW in the kagome d-orbital hosting Bogoliubov Fermi states. △ Less

Submitted 12 October, 2025; originally announced October 2025.

BigBang-Proton Technical Report: Next-Word-Prediction is Scientific Multitask Learner

Authors: Hengkui Wu, Liujiang Liu, Jihua He, Qihao Wang, Keke Zhao, Shuyang Hu, Renle Fu, Dahao Liang, Lingyu Zeng, Bruce Liu, Yuan Liu, Jin Zhan, Jiaqiang Niu, Xinglong Jia, Yaqin Hu, Wenjun Ji, Panpan Chi, Ken Chen, Hengyuan Wu, Yingsi Xin, Yongfeng Zhu, Yuexin Wang, Manqi Ruan, Ningtao Bian, Xiaohua Wu , et al. (1 additional authors not shown)

Abstract: We introduce BigBang-Proton, a unified sequence-based architecture for auto-regressive language modeling pretrained on cross-scale, cross-structure, cross-discipline real-world scientific tasks to construct a scientific multi-task learner. BigBang-Proton incorporates three fundamental innovations compared to mainstream general-purpose LLMs: Theory-Experiment Learning paradigm aligns large-scale nu… ▽ More We introduce BigBang-Proton, a unified sequence-based architecture for auto-regressive language modeling pretrained on cross-scale, cross-structure, cross-discipline real-world scientific tasks to construct a scientific multi-task learner. BigBang-Proton incorporates three fundamental innovations compared to mainstream general-purpose LLMs: Theory-Experiment Learning paradigm aligns large-scale numerical experimental data with theoretical text corpora; Binary Patch Encoding replaces byte pair encoding(BPE) tokenization; Monte Carlo Attention substitutes traditional transformer architectures. Through next-word-prediction pretraining on cross-discipline scientific datasets of real-world problems mixed with general textual corpus, followed by fine-tuning and inference on downstream tasks, BigBang-Proton demonstrates 100\% accuracy in up to 50-digit arithmetic addition operations, performance on par with leading specialized models in particle physics jet tagging, matching MAE of specialized models in inter-atomic potential simulation, performance comparable to traditional spatiotemporal models in water quality prediction, and benchmark-exceeding performance in genome modeling. These results prove that language-guided scientific computing can match or exceed the performance of task-specific scientific models while maintaining multitask learning capabilities. We further hypothesize to scale the pretraining to the universe scale as a fundamental step toward developing material world foundational model. △ Less

Submitted 30 September, 2025; originally announced October 2025.

Comments: 93 pages, 39 figures

MSC Class: 68T05; 68T50; 00A69; 94A99 ACM Class: I.2.6; I.2.7; J.2; I.6.3; K.4.1

Single crystal growth, structural and physical properties, and absence of a charge density wave in Ti_{0.85}Fe6Ge6

Authors: Dechao Cheng, Nour Maraytta, Xiuhua Chen, Xizhi Li, Xueliang Wu, Xiangxiang Jing, Yong Hu, Youpin Gong, Mingquan He, Yisheng Chai, Xiaoyuan Zhou, Pengfei Jiang, Yilin Wang, Michael Merz, Aifeng Wang

Abstract: Kagome materials with charge density waves (CDWs) are fascinating quantum systems, offering an ideal platform to explore intertwined orders and to uncover novel mechanisms behind CDW formation. Chemical models have been developed and applied to predict CDW in $AM_6X_6$-type kagome materials, such as the rattling chain model based on ScV6Sn6 and the magnetic energy-saving model based on FeGe. In th… ▽ More Kagome materials with charge density waves (CDWs) are fascinating quantum systems, offering an ideal platform to explore intertwined orders and to uncover novel mechanisms behind CDW formation. Chemical models have been developed and applied to predict CDW in $AM_6X_6$-type kagome materials, such as the rattling chain model based on ScV6Sn6 and the magnetic energy-saving model based on FeGe. In this study, we successfully synthesized Ti_{0.85}Fe6Ge6 single crystals using the vapor transport method. As predicted by the rattling chain model, these crystals are expected to exhibit kagome CDW behavior. Magnetization measurements indicate that Ti_{0.85}Fe6Ge6 is an easy-axis antiferromagnet with T_N = 488 K and transport measurements reveal metallic behavior primarily driven by electron-type carriers. However, no clear signatures of a CDW were observed in Ti_{0.85}Fe6Ge6. Density functional theory calculations demonstrate a markedly distinct electronic structure compared to related compounds: instead of a carrier-doping-induced rigid shift, the density of states shifted away from the Fermi level. Consistent with our structural investigations, the absence of a CDW and the unusual band structure can be attributed to the bonding characteristic within Ti_{0.85}Fe6Ge6. The strong covalent bonds of Ti-Ge1b, along with the solid Ge1b-Ge1b dimers, prevent the Ti-Ge1b-Ge1b-Ti chain from rattling. The presence of Fe-Fe antibonding state at the Fermi level enhances the spin polarization and depletes the electronic density around the Fermi level. Our results suggest that both the ionic radius and the bonding characteristics of the filler atom are crucial for the formation of CDWs in kagome materials. These factors can serve as supplementary terms to the rattling chain model, providing new insights for the discovery of novel kagome CDW materials. △ Less

Submitted 24 September, 2025; originally announced September 2025.

Comments: 12 pages, 8 figures

Journal ref: Phys. Rev. B 113, 035133 (2026)

The exact relation between the entanglement entropies of the $XY$ and quantum Ising chains with free and fixed boundary conditions

Authors: Tianhao He, Xintian Wu

Abstract: The entanglement entropies of $XY$ chains and quantum Ising chains (QICs) with fixed boundary conditions are studied here. Three kinds of boundary conditions (BCs) are considered: fixed up--up or down--down (the spins at both ends are aligned in the same direction), fixed up--down or down--up (the spins at the two ends are aligned in opposite directions), and fixed--free (the spin at one end is al… ▽ More The entanglement entropies of $XY$ chains and quantum Ising chains (QICs) with fixed boundary conditions are studied here. Three kinds of boundary conditions (BCs) are considered: fixed up--up or down--down (the spins at both ends are aligned in the same direction), fixed up--down or down--up (the spins at the two ends are aligned in opposite directions), and fixed--free (the spin at one end is aligned, and the other end is free). It is shown that i) the entanglement entropy of an $XY$ chain with a fixed--free BC is the sum of those of QICs with a fixed--free BC and with a free--free BC; ii) the entanglement entropy of an $XY$ chain with a fixed up--up boundary condition is the sum of those of QICs with a fixed up--up BC and with a free--free BC; and iii) the entanglement entropy of an $XY$ chain with a fixed up--down BC is the sum of that of a QIC with a fixed up--up BC and that of the first excited state of a QIC with a free--free BC. △ Less

Submitted 20 September, 2025; originally announced September 2025.

Exploring the nature of the emergent gauge field in composite-fermion metals: A large-scale microscopic study

Authors: Amogh Anakru, Mytraya Gattu, Ajit C. Balram, Xiao-Chuan Wu, Prashant Kumar, Zhen Bi, J. K. Jain

Abstract: Field theories of the composite-fermion (CF) metal model it as a Fermi sea of composite fermions coupled to an emergent gauge field. Within a random phase approximation, these theories predict that the Landau damping of the gauge field resulting from its coupling to the low-energy, long-wavelength CF particle-hole excitations modifies the electrons' density-density correlation function related to… ▽ More Field theories of the composite-fermion (CF) metal model it as a Fermi sea of composite fermions coupled to an emergent gauge field. Within a random phase approximation, these theories predict that the Landau damping of the gauge field resulting from its coupling to the low-energy, long-wavelength CF particle-hole excitations modifies the electrons' density-density correlation function related to the static structure factor $S(q)$ at wave vector $q$. This produces a non-analytic correction $\propto q^{3}\ln q$ to $S(q)$ (with the magnetic length $\ell_{B}=1$). Thanks to the recently developed quaternion formulation for Jain-Kamilla projection of CF wave functions, the evaluation of $S(q)$ from the accurate microscopic theory of composite fermions has now become possible for systems containing as many as $N=900$ CFs, which enables a reliable determination of the small-$q$ behavior of $S(q)$. We study CF metals corresponding to electrons at Landau level filling factors $ν=1/2$ and $1/4$, and for completeness, also of bosons at $ν=1$ and $1/3$. In the $q\rightarrow0$ limit, our microscopic calculation reveals a $q^{3}$ term in $S(q)$ of the CF metals rather than $q^{3} \ln q$. This behavior is well-predicted by a model of a non-interacting Fermi sea of dipolar CFs, which also obtains its coefficient accurately. △ Less

Submitted 8 September, 2025; originally announced September 2025.

Comments: Main: 5 pages + 1 fig. SM: 5 pages + 3 figs. We welcome all comments

Journal ref: Phys. Rev. Lett. 135, 246503 (2025)

Robust field re-entrant superconductivity in ferromagnetic infinite-layer rare-earth nickelates

Authors: Mingwei Yang, Jiayin Tang, Xianfeng Wu, Heng Wang, Wenjing Xu, Haoliang Huang, Zhicheng Pei, Wenjie Meng, Guangli Kuang, Jinfeng Xu, Sixia Hu, Chuanying Xi, Li Pi, Qingyou Lu, Ziqiang Wang, Qikun Xue, Zhuoyu Chen, Danfeng Li

Abstract: Superconductivity and ferromagnetism are naturally competing, while their interplay can give rise to exotic quantum phases, such as triplet pairing, exemplified by heavy-fermion compounds like UTe$_2$, where magnetic fluctuations stabilise multiple superconducting states. However, such phenomena have remained elusive in high-temperature superconductors. Here we report the discovery of robust field… ▽ More Superconductivity and ferromagnetism are naturally competing, while their interplay can give rise to exotic quantum phases, such as triplet pairing, exemplified by heavy-fermion compounds like UTe$_2$, where magnetic fluctuations stabilise multiple superconducting states. However, such phenomena have remained elusive in high-temperature superconductors. Here we report the discovery of robust field-induced re-entrant superconductivity in heavily Eu-doped infinite-layer nickelate Sm$_{0.95-x}$Ca$_{0.05}$Eu$_x$NiO$_2$. In the heavily over-doped regime, we observe a remarkable superconducting state that emerges under high magnetic fields ($>$ 6 Tesla) after the initial suppression of zero-field superconductivity. Both zero-resistance transport and Meissner diamagnetic effect confirm the superconducting nature of this high-field phase, which persists up to at least 45 Tesla. This re-entrant behaviour is featured by the coexistence of ferromagnetism and superconductivity on distinct sublattices -- magnetic Eu$^{2+}$ ions and the Ni-O planes, respectively. Such an exotic state may arise from the compensation between external and internal exchange fields (Jaccarino-Peter effect) combined with magnetic fluctuation-enhanced pairing near quantum criticality. Our findings establish infinite-layer nickelates as a unique platform for high-temperature ferromagnetic superconductivity, opening new avenues for discovering and manipulating unconventional quantum phases in strongly correlated materials. △ Less

Submitted 22 August, 2025; v1 submitted 20 August, 2025; originally announced August 2025.

Comments: Manuscript under review. 26 pages, 11 figures