Showing 1–50 of 338 results for author: Jiang, Z

Elementary magnons and interacting multi-magnon quasiparticles in the effective spin-$\frac{1}{2}$ kagome-staircase magnet Co$_{3}$V$_{2}$O$_{8}$

Authors: Yuan Xiao, Jiajun Mo, Zhenmeng Jiang, Haoyang Leng, Otkur Omar, Yanjun Li, Fengyi Song, Jianjun Ying, Shang Gao

Abstract: The excitation spectrum of an anisotropic magnet provides a direct link between its microscopic Hamiltonian and interaction-driven quasiparticles. Here we use high-resolution time-domain terahertz spectroscopy to map the magnetic excitations of the three-dimensional kagome-staircase compound Co$_{3}$V$_{2}$O$_{8}$ as functions of temperature and magnetic field. At low energies, polarization-resolv… ▽ More The excitation spectrum of an anisotropic magnet provides a direct link between its microscopic Hamiltonian and interaction-driven quasiparticles. Here we use high-resolution time-domain terahertz spectroscopy to map the magnetic excitations of the three-dimensional kagome-staircase compound Co$_{3}$V$_{2}$O$_{8}$ as functions of temperature and magnetic field. At low energies, polarization-resolved spectra identify magnetic-dipole-active one-magnon modes and track their evolution across the ferromagnetic and spin-density-wave phases. Combining their field dependence with previously reported inelastic-neutron-scattering dispersions, we determine an effective spin-$\frac{1}{2}$ Hamiltonian with strongly anisotropic exchange that quantitatively reproduces the one-magnon spectrum. This model provides a noninteracting benchmark for the high-energy response, where we observe sharp branches with field slopes that are two to four times those of the one-magnon modes, together with anticrossings between branches of different magnon numbers. Their sharpness, polarization dependence, and departure from the calculated multi-magnon continua identify them as interacting multi-magnon quasiparticles that can be stabilized by strong exchange anisotropy. △ Less

Submitted 9 August, 2026; originally announced August 2026.

Revealing Intrinsic Anisotropy of Collective Magnetic Excitations in Twinned Crystals of a Kitaev-Heisenberg Quantum Magnet

Authors: Naipeng Zhang, Nikolai Simonov, Mykhaylo Ozerov, Sumedh Rathi, Nolan Heffner, Sara Huszar, Long Chen, Haidong Zhou, Guangxin Ni, Chaebin Kim, Martin Mourigal, Stephen M. Winter, Zhigang Jiang, Dmitry Smirnov

Abstract: Quantum magnets with competing interactions often emerge from delicate balances among microscopic parameters, making it essential to disentangle intrinsic spin dynamics from extrinsic disorder effects. Here, we introduce a multimodal optical approach combining magneto-infrared spectroscopy with domain-resolved micro-Raman spectroscopy at high magnetic fields to reconstruct the intrinsic magnetic e… ▽ More Quantum magnets with competing interactions often emerge from delicate balances among microscopic parameters, making it essential to disentangle intrinsic spin dynamics from extrinsic disorder effects. Here, we introduce a multimodal optical approach combining magneto-infrared spectroscopy with domain-resolved micro-Raman spectroscopy at high magnetic fields to reconstruct the intrinsic magnetic excitation spectrum of twinned crystals of the Kitaev-Heisenberg quantum magnet Na$_3$Co$_2$SbO$_6$. Far-infrared spectroscopy reveals multiple field-tunable magnetic excitations, but the intrinsic response is obscured by replica features arising from twin domains. By correlating magneto-infrared and domain-resolved Raman spectra, we isolate the single-domain magnon response and uncover a pronounced twofold in-plane magnon anisotropy. This anisotropy far exceeds that expected from the measured in-plane g-factor anisotropy and is instead dominated by anisotropic bond-dependent exchange interactions. By unifying high-field, high-resolution and spatially selective optical probes, our work establishes a broadly applicable framework for revealing intrinsic spin dynamics and constraining the spin Hamiltonian in multidomain quantum magnets. △ Less

Submitted 3 August, 2026; originally announced August 2026.

Active Passivation Tunes Hotspot Locations in GaN Transistors with In Situ Thermal Mechanical Visualization

Authors: Yicheng Wei, Sihang Liu, Zimu Jiang, jinquan Zhang, Zifeng Huang, Han Yang, Yang He, Jin Wei, Zhe Cheng

Abstract: Efficient thermal dissipation has become critical in emerging electronic devices. However, most existing studies have primarily focused on engineering heat dissipation pathways, largely overlooking the intrinsic behavior of the heat source itself. We demonstrate an active passivation technology that proactively tunes hotspot locations in GaN transistors. By adjusting the active passivation layer l… ▽ More Efficient thermal dissipation has become critical in emerging electronic devices. However, most existing studies have primarily focused on engineering heat dissipation pathways, largely overlooking the intrinsic behavior of the heat source itself. We demonstrate an active passivation technology that proactively tunes hotspot locations in GaN transistors. By adjusting the active passivation layer length, the hotspot is shifted from the gate edge to the drain-side AP edge, establishing a clear one-to-one spatial correlation. In-situ thermal-mechanical visualization via micro-Raman thermography, combined with multi-physics electro-thermal-mechanical simulations, directly captures the spatial redistribution of both temperature and thermal stress profiles. Electrical analysis confirms that this hotspot migration is driven by the spatial shift of the peak electric field and localized Joule heating. This proactive heat-source tuning strategy provides critical design guidelines for power electronics. △ Less

Submitted 2 August, 2026; originally announced August 2026.

Precision quantum simulation of magnon spectra and interactions

Authors: Trond I. Andersen, Nikita Astrakhantsev, Jeronimo Martinez, Will Morong, Johannes Motruk, Dario Rossi, Brayden Ware, Bryce Kobrin, Weijie Wu, Elizabeth Bennewitz, Manuel Rudolph, Tom Westerhout, Amira Abbas, Rajeev Acharya, Laleh Aghababaie Beni, Ross Alcaraz, Sayra Alcaraz, Markus Ansmann, Frank Arute, Kunal Arya, Walt Askew, Juan Atalaya, Christopher Ayala, Ryan Babbush, Brian Ballard , et al. (307 additional authors not shown)

Abstract: Quantum simulation promises to advance materials discovery by accurately simulating complex states of matter, their microscopic excitations, and macroscopic response functions. The central challenge in resolving the underlying interacting dynamics is to combine high-fidelity evolution with the sophisticated control necessary to manipulate individual quasi-particles in quantum many-body states. Her… ▽ More Quantum simulation promises to advance materials discovery by accurately simulating complex states of matter, their microscopic excitations, and macroscopic response functions. The central challenge in resolving the underlying interacting dynamics is to combine high-fidelity evolution with the sophisticated control necessary to manipulate individual quasi-particles in quantum many-body states. Here, we report on high-precision simulation of both linear and non-linear response functions in a 2D XY spin-1/2 magnet using an analog-digital superconducting processor of up to 97 qubits. By interleaving digital gates with analog evolution precisely characterized via Hamiltonian learning, we selectively excite magnons at tunable energy densities. Measuring first the linear magnon response -- a central probe in neutron-scattering experiments -- we extract temperature-dependent spectra and lifetimes. Our results reveal stark variations in magnon decay rates across the Brillouin zone, with enhancement near van Hove singularities and suppression for edge-localized modes. Next, we perform a suite of nonlinear measurements, including the study of self-scattering mechanisms, as well as pump-probe spectroscopy to directly characterize the magnon interactions. While matrix-product state simulations capture the dynamics well in either small systems or at low temperatures, their predictions become inaccurate away from these limits. This work demonstrates precise simulation of the interacting dynamics in quantum magnets, and provides key insights into quasi-particles and their microscopic scattering mechanisms. △ Less

Submitted 14 July, 2026; originally announced July 2026.

Calibration of systematic distortions in quantum emitter localization microscopy for deterministic nanophotonic fabrication

Authors: Chenxi Ma, Maximilian Heller, Timon Handrup, Yiteng Zhang, Tobias M. Krieger, Thomas Oberleitner, Zenghui Jiang, Xian Zheng, Eddy P. Rugeramigabo, Folke Dencker, Armando Rastelli, Fei Ding, Michael Zopf

Abstract: Quantum photonic technologies greatly benefit from quantum light emitters with high brightness, indistinguishability, and reliable polarization characteristics. Achieving optimal performance relies on the accurate localization of emitters and their deterministic integration into tailored photonic structures with nanometer-scale accuracy. Although marker-based photoluminescence imaging techniques c… ▽ More Quantum photonic technologies greatly benefit from quantum light emitters with high brightness, indistinguishability, and reliable polarization characteristics. Achieving optimal performance relies on the accurate localization of emitters and their deterministic integration into tailored photonic structures with nanometer-scale accuracy. Although marker-based photoluminescence imaging techniques can achieve statistical fitting uncertainties below 10 nm, the ultimate integration yield is often limited by uncorrected systematic distortions in custom cryo-optical setups that compromise metrological accuracy. Here, we present an in situ calibration protocol that uses lithographically defined gold nanodisk arrays as references to calibrate optical distortions with a Zernike vector-field model. On held-out validation patterns beyond the calibration dataset, this correction reduces the residual systematic bias to 5.3 nm with a 2D scatter of 24.6 nm across the analyzed field of view. Furthermore, we demonstrate that applying this correction to the deterministic fabrication of circular mesa structures around semiconductor quantum dots reduces the variance in emission polarization by 49%, indicating improved registration accuracy. This calibration strategy offers a practical route to high-yield deterministic integration of quantum emitters into scalable quantum photonic circuits. △ Less

Submitted 6 July, 2026; originally announced July 2026.

Binary Dipolar Condensates of Dysprosium Isotopes with Tunable Spatial Order

Authors: Shenshuang Nie, Zibin Jiang, Junrong Huang, Xiao Luo, Fucheng Qin, Kaiyue Wang, Mingyang Guo

Abstract: Dipolar quantum mixtures provide a route to many-body phases in which long-range anisotropic interactions couple with density, composition and spatial order. Here we realize a new quantum-degenerate dipolar mixture of $^{162}$Dy and $^{164}$Dy in a single-species-like apparatus. The mixture combines nearly matched single-particle Hamiltonians, tunable interactions and composition parameters, and i… ▽ More Dipolar quantum mixtures provide a route to many-body phases in which long-range anisotropic interactions couple with density, composition and spatial order. Here we realize a new quantum-degenerate dipolar mixture of $^{162}$Dy and $^{164}$Dy in a single-species-like apparatus. The mixture combines nearly matched single-particle Hamiltonians, tunable interactions and composition parameters, and isotope-resolved characterization. Tuning the interaction balance and relative composition reorganizes the coupled condensates from a miscible state into core--shell-like, side-by-side, and exchanged core--shell-like immiscible configurations. These results establish dysprosium isotope mixtures as a compact and versatile platform for multicomponent dipolar quantum matter, ranging from impurity physics to binary supersolidity. △ Less

Submitted 30 June, 2026; v1 submitted 25 June, 2026; originally announced June 2026.

Comments: 11 pages, 4+4 figures

Band offsets and stability of WSe$_2$/RuCl$_3$ van der Waals charge-transfer contacts

Authors: Thomas S. Nielsen, Edvard Solbrekken, Christian Overby, Christian V-B. Fokdal, Alfred J. H. Jones, Zhihao Jiang, Chakradhar Sahoo, Kenji Watanabe, Takashi Taniguchi, Søren Ulstrup

Abstract: The layered Mott insulator $α$-RuCl$_3$ induces degenerate hole-doping in two-dimensional semiconductors due to its large electron affinity, making it a promising charge-transfer material for establishing ohmic contacts in electronic devices. In order to assess the applicability and guide the design of devices incorporating RuCl$_3$ it is critical to determine the electronic structure and robustne… ▽ More The layered Mott insulator $α$-RuCl$_3$ induces degenerate hole-doping in two-dimensional semiconductors due to its large electron affinity, making it a promising charge-transfer material for establishing ohmic contacts in electronic devices. In order to assess the applicability and guide the design of devices incorporating RuCl$_3$ it is critical to determine the electronic structure and robustness of the band offsets that underpin the transport properties of semiconductors in contact with RuCl$_3$. Here, we apply micro-focused angle-resolved photoemission spectroscopy to determine the electronic structure of single-layer WSe$_2$ contacted to RuCl$_3$ on hexagonal boron nitride substrates. We find that formation of a functioning WSe$_2$/RuCl$_3$ contact leads to a valence band shift of $(0.68 \pm 0.05)$ eV towards the Fermi energy in WSe$_2$. The charge transfer effect is challenging to observe as it depends sensitively on fabrication conditions such as solvent exposure, quality of interface encapsulation and heating of RuCl$_3$, imposing strict requirements on device design to attain high-quality contacts. △ Less

Submitted 23 June, 2026; originally announced June 2026.

Comments: 7 pages, 3 figures

Isometrization of Tensor Network States via Gauge Propagation

Authors: Zhiyu Jiang, Hiroshi Ueda

Abstract: We introduce a gauge-propagation approach for approximately converting generic tensor-network states into an isometric tensor-network form with a prescribed orthogonality center. In one dimension, this propagation is exact because the non-isometric factor produced by a QR or singular-value decomposition is supported on a single virtual bond. In higher-dimensional networks, however, a local step ca… ▽ More We introduce a gauge-propagation approach for approximately converting generic tensor-network states into an isometric tensor-network form with a prescribed orthogonality center. In one dimension, this propagation is exact because the non-isometric factor produced by a QR or singular-value decomposition is supported on a single virtual bond. In higher-dimensional networks, however, a local step can have several outgoing directions, and the residual factor is generally not separable into independent single-bond contributions. We address this local obstruction by approximating a local tensor, or a contracted local cluster, by structured terms consisting of an isometric factor multiplied by a tensor product of output-leg factors. The isometric factor is retained at the current site or cluster, while the output-leg factors are absorbed into neighboring tensors along the propagation directions. This construction applies to general local input-output partitions for which the input-side dimension is no smaller than the output-side dimension and provides a local truncation criterion for gauge propagation. Benchmarks on random tensors show that the proposed decomposition is effective in the low-term regime and that the residual decreases for larger local clusters. For the loop-gas tensor representation of the Kitaev spin liquid, two structured terms reduce the local residual to numerical precision, and the same cluster refinement further lowers the leading-term truncation error and reduces error accumulation during gauge propagation on a finite honeycomb network. These results identify a propagation-compatible local decomposition as a useful building block for approximate isometrization and as a potential initializer or preconditioner for variational isoTNS algorithms. △ Less

Submitted 19 August, 2026; v1 submitted 21 June, 2026; originally announced June 2026.

Comments: 17 pages, 6 figures, 1 table

Observation and Control of Spontaneous Magnon Emission from Spin Ensembles in 2D Hexagonal Boron Nitride

Authors: Ling-Jie Zhou, Jayakrishnan M. P. Nair, Senlei Li, Thomas Poirier, Yiran Zhao, Zelong Xiong, Sumedh Rathi, Jingcheng Zhou, Zhigang Jiang, Hailong Wang, James H. Edgar, Benedetta Flebus, Chunhui Rita Du

Abstract: Hybrid systems consisting of color centers and magnetic materials provide an appealing solid-state platform for advancing the burgeoning quantum technological revolution. Exploring novel coupling mechanisms between optically active spin defects and quantum degrees of freedom is directly relevant in this context. Here, we report observation and control of spontaneous magnon emission from boron-vaca… ▽ More Hybrid systems consisting of color centers and magnetic materials provide an appealing solid-state platform for advancing the burgeoning quantum technological revolution. Exploring novel coupling mechanisms between optically active spin defects and quantum degrees of freedom is directly relevant in this context. Here, we report observation and control of spontaneous magnon emission from boron-vacancy centers in 2D hexagonal boron nitride (hBN), an unconventional qubit-magnon dipole coupling channel that dominates in the near-zero temperature limit. The spontaneous magnon emission process starts to be overshadowed by thermal magnon effect as temperature increases, reflecting the crossover from an emission-dominated, effectively cold magnon reservoir to a thermally occupied spin bath where absorption and stimulated processes restore balance. By increasing the spin defect density, we further present that spontaneous magnon emission into a common spin bath could help establish quantum correlations in dense hBN spin ensembles. Our results are quantitatively captured by detailed theoretical modeling, bringing insights into understanding qubit-magnon coupling, correlated spin dynamics, and many-body physics of color centers in the quantum regime. △ Less

Submitted 18 June, 2026; originally announced June 2026.

Orbital-selective band evolution and out-of-plane correlation in the FeGe-family kagome antiferromagnet ScFe$_6$Ge$_6$

Authors: Jae Hyuck Lee, Ze Yan, Tongrui Li, Yichen Yang, Dirk Wulferding, Jongkeun Jung, Zhicheng Jiang, Mao Ye, Zhengtai Liu, Changyoung Kim, Soohyun Cho, Yanfeng Guo, Dawei Shen

Abstract: In strongly correlated materials such as high-temperature superconductors, the relation between charge density wave (CDW) order and magnetism remains an important unresolved problem. FeGe is the first kagome metal known to exhibit CDW order deep within an antiferromagnetic state, accompanied by an unconventional evolution of lattice symmetry. To elucidate the general conditions governing such spin… ▽ More In strongly correlated materials such as high-temperature superconductors, the relation between charge density wave (CDW) order and magnetism remains an important unresolved problem. FeGe is the first kagome metal known to exhibit CDW order deep within an antiferromagnetic state, accompanied by an unconventional evolution of lattice symmetry. To elucidate the general conditions governing such spin-correlated CDW order, we investigate ScFe$_6$Ge$_6$, which lacks CDW order and therefore exhibits reduced involvement of charge degrees of freedom while retaining other properties of FeGe. Instead of a CDW order, ScFe$_6$Ge$_6$ undergoes a magnetic transition at $T^*$ = 195 K. Across this transition, angle-resolved photoemission and Raman spectroscopy reveal orbital-selective behavior confined to a single kagome Dirac band, together with electron-phonon and magnetoelastic coupling to an out-of-plane phonon mode. These results suggest that orbital-selective physics and out-of-plane correlations play enhanced roles in realizing spin-correlated CDW order in magnetic kagome metals. △ Less

Submitted 15 June, 2026; originally announced June 2026.

Comments: 11 pages, 4 figures

Quenching of Nonrelativistic $p$-Wave Spin Splitting by Reduced $c\text{-}f$ Coupling in $\text{CeNiAsO}$

Authors: Xinnuo Zhang, Zhicheng Jiang, Shibo Shen, Jian Yuan, Junseo Yoo, Xun Ma, Mao Ye, Jishan Liu, Zhengtai Liu, Changyoung Kim, Yanfeng Guo, Yilin Wang, Dawei Shen

Abstract: The application of spin-space group symmetries to noncollinear antiferromagnets has led to the prediction of odd-parity, nonrelativistic spin splittings, making the physical realization of a practical $p$-wave magnet a central pursuit in spintronics. The layered heavy-fermion oxypnictide $\text{CeNiAsO}$ has been widely regarded as a prototypical platform to verify this paradigm. Here, we investig… ▽ More The application of spin-space group symmetries to noncollinear antiferromagnets has led to the prediction of odd-parity, nonrelativistic spin splittings, making the physical realization of a practical $p$-wave magnet a central pursuit in spintronics. The layered heavy-fermion oxypnictide $\text{CeNiAsO}$ has been widely regarded as a prototypical platform to verify this paradigm. Here, we investigate the electronic structure of single-crystal $\text{CeNiAsO}$ using high-resolution, ultra-low-temperature and resonant angle-resolved photoemission spectroscopy (ARPES), and $ab-initio$ calculations. Across the consecutive magnetic transitions into the ordered phases, our spectroscopic data reveal neither the expected band folding associated with a spin density wave nor any observable $p$-wave spin splitting, demonstrating that the conduction bands retain full degeneracy. By tracking the temperature dependence of the Ce 4$f$ spectral weight via resonant ARPES, we find negligible $c\text{-}f$ hybridization near the Fermi level within magnetically ordered states, confirming that the Ce 4$f$ electrons reside close to the localized limit. Our findings establish a clear many-body constraint on the projection of real-space magnetic symmetries onto momentum-space electronic bands, demonstrating that symmetry classifications constitute a necessary framework but are not a sufficient condition for nonrelativistic spin splittings in the presence of strong electronic correlations. △ Less

Submitted 12 June, 2026; v1 submitted 1 June, 2026; originally announced June 2026.

Comments: 7 pages, 4 figures

Layer-Resolved Nonlinear Optics in Finite-Thickness Two-Dimensional Systems

Authors: Liangting Ye, Chengzhi Wu, Zeyu Jiang, Bing Huang

Abstract: Nonlinear optical (NLO) responses in two-dimensional quantum-confined systems are typically described within bulk-based frameworks as macroscopic spatial averages. In finite-thickness van der Waals multilayers directly relevant to nanoscale devices, this picture substantially breaks down. Here, we establish a general symmetry-based framework for classifying second-order NLO responses in multilayer… ▽ More Nonlinear optical (NLO) responses in two-dimensional quantum-confined systems are typically described within bulk-based frameworks as macroscopic spatial averages. In finite-thickness van der Waals multilayers directly relevant to nanoscale devices, this picture substantially breaks down. Here, we establish a general symmetry-based framework for classifying second-order NLO responses in multilayers. We reveal a layer-resolved organization into skin, weak-skin, and hidden effects governed by local symmetry and stacking order. First-principles calculations for both nonmagnetic and spin-polarized systems confirm our predictions, demonstrating that stacking alone suffices to dramatically reshape both the spatial pattern and magnitude of the NLO response, a phenomenon not explainable within standard bulk theory. Our results establish stacking geometry as an effective knob for engineering surface-selective NLO responses in layered materials. △ Less

Submitted 1 June, 2026; originally announced June 2026.

Comments: 9 pages, 5 figures

Spin-Spiral Enhancement of Ultrafast Light-Polarization-Robust Magnetization

Authors: Yirui Lu, Zeyu Jiang, Bing Huang

Abstract: Ultrafast light-driven magnetization, a frontier in quantum magneto-optics, has traditionally relied on circularly polarized lasers to provide external angular momentum. While increasing efforts have aimed to achieve light-polarization-robust (LPR) magnetization that is insensitive to the form of external light excitation, the underlying mechanism remains largely unclear. Here, we establish the sy… ▽ More Ultrafast light-driven magnetization, a frontier in quantum magneto-optics, has traditionally relied on circularly polarized lasers to provide external angular momentum. While increasing efforts have aimed to achieve light-polarization-robust (LPR) magnetization that is insensitive to the form of external light excitation, the underlying mechanism remains largely unclear. Here, we establish the symmetry-constrained rule for LPR magnetization in antiferromagnetic systems. Through real-time time-dependent density functional theory calculations, we observe the strong LPR magnetization in spin-spiral magnets and its suppression in collinear antiferromagnets, confirming our theory. Strikingly, laser excitation induces real-space demagnetization, rotation, and oscillation of atomic spins in spin-spiral monolayer NiI$_2$, whereas rotation is largely suppressed in conventional collinear antiferromagnets. Our work reveals a novel microscopic pathway for ultrafast magnetization that is independent of light polarization, paving the way for advanced femtosecond spin control. △ Less

Submitted 29 May, 2026; originally announced May 2026.

Termination-Dependent Surface States and Magnetic Fingerprints of Chiral Helimagnet Cr1/3TaS2

Authors: Bo Liang, Xue Li, Congcong Le, Zirui Wu, Wenpei Zhu, Neng Cai, Yong-Chang Lau, Xianxin Wu, Jiayu Liu, Zhanfeng Liu, Hongen Zhu, Tongrui Li, Zhicheng Jiang, Yu Huang, Wenchuan Jing, Xun Ma, Qi Jiang, Hang Li, Zhihao Cai, Xuezhi Chen, Gexing Qu, Yiwei Cheng, Bing-Jie Chen, Zhengtai Liu, Dawei Shen , et al. (14 additional authors not shown)

Abstract: Chiral helimagnets based on intercalated transition-metal dichalcogenides, characterized by nano-scale spin ordering, provide a powerful route to engineer chiral spin textures (e.g. the topologically protected magnetic solitons) and emergent electronic functionality at reduced dimensions, where surface and interface states often dominate device operation. However, despite growing interest, direct… ▽ More Chiral helimagnets based on intercalated transition-metal dichalcogenides, characterized by nano-scale spin ordering, provide a powerful route to engineer chiral spin textures (e.g. the topologically protected magnetic solitons) and emergent electronic functionality at reduced dimensions, where surface and interface states often dominate device operation. However, despite growing interest, direct experimental studies of termination-dependent surface electronic structures and their temperature-driven magnetic evolution remain largely unexplored, hindering a microscopic understanding of the electronic states that is crucial for the development of low-dimensional spintronic devices. Here, for the first time, taking Cr1/3TaS2 as a representative example, we systematically investigate the termination-dependent surface electronic states of the chiral helimagnets and uncover their distinct temperature evolution across the magnetic transition (TC~142K) by combining high-resolution ARPES with a micro-focused beam and surface-state-resolved first-principles calculations. The TaS2-terminated surface hosts folded monolayer-like TaS2 bands under the $\sqrt3\times\sqrt3$ superlattice potential and a shallow triangular electron pocket at the superlattice $\bar K$ point arising from Cr-Ta orbital hybridization. In contrast, the Cr-terminated surface exhibits reconstructed hole pockets with pronounced magnetic band splitting. This splitting disappears above TC and closely follows the chiral helimagnetic order parameter, providing a direct spectroscopic fingerprint of chiral helimagnetic order. In addition, multiple ultranarrow Cr-d-derived surface flat bands are resolved. These findings establish Cr1/3TaS2 as a model system in which surface electronic states are strongly coupled to chiral magnetism, opening new opportunities for chiral spintronic and valleytronic micro/nanodevices. △ Less

Submitted 23 May, 2026; originally announced May 2026.

Light-Driven Ferroic Switching Enables Reversible Control of Hydrogen Adsorption Thermodynamics

Authors: Xueqing Wan, Zhenlong Zhang, Charles Paillard, Jian Zhou, Jinyang Ni, Chuanlu Yang, Zhijun Jiang, Laurent Bellaiche

Abstract: Reversible ultrafast switching of surface thermodynamics is highly desirable for hydrogen storage and catalysis yet remains elusive at the nanoscale. Here we demonstrate that photoinduced ferroic-order switching in two-dimensional ionic ferroelectric monolayers enables rapid, reversible control of hydrogen binding. In TiGeSe$_3$, carrier-density-driven redistribution of transition-metal 3\textit{d… ▽ More Reversible ultrafast switching of surface thermodynamics is highly desirable for hydrogen storage and catalysis yet remains elusive at the nanoscale. Here we demonstrate that photoinduced ferroic-order switching in two-dimensional ionic ferroelectric monolayers enables rapid, reversible control of hydrogen binding. In TiGeSe$_3$, carrier-density-driven redistribution of transition-metal 3\textit{d} orbital occupations triggers a sequential evolution from the ferroelectric ground state to paraelectric phases with staggered or Zig-Zag antiferromagnetic order. This switch continuously tunes the hydrogen adsorption free energy from 0.33 to 1.11 eV, shifting the interface from near-thermoneutrality to spontaneous desorption. Nonadiabatic dynamics indicate that electron-phonon coupling promotes nonthermal H release, while picosecond carrier recombination rapidly restores the initial ferroic order, closing an ultrafast reversible cycle. Generality is further validated in AgBiP$_2$Se$_6$ and CuInP$_2$S$_6$, establishing ferroic order as an optically addressable knob for dynamic thermodynamic reconfiguration beyond static design. △ Less

Submitted 22 May, 2026; originally announced May 2026.

Comments: 21 pages, 6 figures

Odd-Parity Chiral Magnons in Collinear Antiferromagnetic Multiferroics: Symmetry Classification and Ferroelectric Switching

Authors: Quanchao Du, Zhenlong Zhang Yuanjun Jin, Rui Li, Haibo Xie, Jinlian Lu, Zhe Wang, Zhijun Jiang, Lei Zhang, Jinyang Ni

Abstract: The coupling between ferroelectrics and magnetism presents a promising avenue for low-dissipation spintronic devices. However, such couplings remain rare, and the direct realization of magnetic order driven by ferroelectric switching in insulators continues to pose a significant challenge. Here, we identify a class of collinear antiferromagnetic multiferroics in which intra-sublattice Dzyaloshinsk… ▽ More The coupling between ferroelectrics and magnetism presents a promising avenue for low-dissipation spintronic devices. However, such couplings remain rare, and the direct realization of magnetic order driven by ferroelectric switching in insulators continues to pose a significant challenge. Here, we identify a class of collinear antiferromagnetic multiferroics in which intra-sublattice Dzyaloshinskii-Moriya interaction (DMI) induces odd-parity chiral magnons that are reversible via ferroelectric switching. Leveraging the charge-neutral nature of magnons, such multiferroics enable non-volatile ferroelectric control over magnon spin splitting, Hall transport, and spin polarization in antiferromagnetic insulators. Remarkably, magnetic group analysis and spin wave calculations reveal that the chiral splitting adopts three planar odd-parity forms, f-wave, p-wave, and fully-gapped types, with an intriguing Néel vector dependence. Furthermore, density functional theory calculations validate various material candidates, ranging from two-dimensional to bulk systems. Our work provides new insights into the realization of odd-parity chiral magnons in collinear antiferromagnets and opens new avenues for magnetoelectric coupling mechanisms in multiferroics. △ Less

Submitted 24 May, 2026; v1 submitted 21 May, 2026; originally announced May 2026.

Comments: 5 figures

High-performance linear-scaling electronic structure method via chromatic superposition states

Authors: Zhikang Jiang, Zhizhi Xiao, Mingfa Tang, Weiyu Li, Zhaoru Sun, Ke Xia, Youqi Ke

Abstract: We introduce a high-performance linear-scaling electronic structure method that employs chromatic superposition states (CSS) as a low-dimensional, high-fidelity representation, which can be orders of magnitude smaller than the full Hilbert space. Grounded in the system's finite correlation length, the CSS representation aggregates the uncorrelated orbitals into a single basis via a graph-coloring… ▽ More We introduce a high-performance linear-scaling electronic structure method that employs chromatic superposition states (CSS) as a low-dimensional, high-fidelity representation, which can be orders of magnitude smaller than the full Hilbert space. Grounded in the system's finite correlation length, the CSS representation aggregates the uncorrelated orbitals into a single basis via a graph-coloring scheme, and is independent of the system size yet accurately preserves all sparse operators in solving the Kohn-Sham equations. The projection onto CSSs is efficiently computed by employing the block-Lanczos Krylov method which features high hardware efficiency and linear-scaling cost, enabling fast calculation of large-scale Kohn-Sham density matrix. We show that this method already outperforms previous linear-scaling density matrix purification method by more than one order of magnitude in computational speed at even small scale, while preserving high accuracy. The practical utility of the CSS method is demonstrated through molecular dynamics simulation of a 10000 $H_2O$, and self-consistent calculation of a 1-million $H_2O$ with modest resources. △ Less

Submitted 20 May, 2026; originally announced May 2026.

Comments: Submitted to npj Computational Materials

Prebiotic magnetite enables chirality-magnetic surface feedback

Authors: Jose A. P. M. Devienne, Ziwei Liu, Clancy Z. Jiang, Nicholas J. Tosca, Thomas Ginnis, Dimitar D. Sasselov, Richard J. Harrison, S. Furkan Ozturk

Abstract: The emergence of biomolecular homochirality requires both an initial symmetry-breaking event and a mechanism to amplify and preserve a chiral imbalance. Magnetic minerals have been shown to function as chiral agents through the chiral-induced spin selectivity (CISS) effect and may have enabled homochirality on early Earth, yet the magnetic properties of magnetite formed under realistic prebiotic c… ▽ More The emergence of biomolecular homochirality requires both an initial symmetry-breaking event and a mechanism to amplify and preserve a chiral imbalance. Magnetic minerals have been shown to function as chiral agents through the chiral-induced spin selectivity (CISS) effect and may have enabled homochirality on early Earth, yet the magnetic properties of magnetite formed under realistic prebiotic conditions remain unexplored. Here we show that magnetite synthesized through two geochemically plausible pathways - UV-driven photo-oxidation and nitrite-mediated oxidation of Fe(II) - produces particles dominated by single-vortex and multi-vortex magnetic domain states. Magnetic measurements and electron microscopy confirm that these populations differ markedly from the nano-fabricated thin-film substrates conventionally used in previous CISS experiments. Using 3D micromagnetic simulations, we demonstrate that single-domain and vortex-state grains undergo irreversible, exchange-driven re-magnetization when interacting with spin-polarized homochiral compounds. This magnetic irreversibility provides a robust mechanism for storing and reinforcing weak chiral bias, suggesting that prebiotic magnetite could have contributed to the emergence and stabilization of persistent chiral bias on the early Earth. △ Less

Submitted 19 May, 2026; originally announced May 2026.

Polymeric Solvents Control Swelling-Induced Surface Creasing

Authors: Zechao Jiang, Zhaoyu Ding, Shaohua Yang, Ye Xu, Dongshi Guan, Abdelhamid Maali, Joshua D Mcgraw, Thomas Salez, Zaicheng Zhang, Xingkun Man

Abstract: Surface creasing in swelling polymer gels is commonly attributed to compressive strain or interlayer mismatch, yet its general control remains unclear. Here we show that solvent polymerization degree $N_{\rm s}$ provides an independent control parameter for crease onset in surface-bound polydimethylsiloxane gels swollen by silicone oils. Despite nearly identical swelling kinetics and through-thick… ▽ More Surface creasing in swelling polymer gels is commonly attributed to compressive strain or interlayer mismatch, yet its general control remains unclear. Here we show that solvent polymerization degree $N_{\rm s}$ provides an independent control parameter for crease onset in surface-bound polydimethylsiloxane gels swollen by silicone oils. Despite nearly identical swelling kinetics and through-thickness solvent concentration profiles, we observe a transition from creased to stable surfaces with increasing $N_{\rm s}$. A theory coupling swelling thermodynamics and mechanical stability reveals that polymeric solvents reduce the mixing entropy and thereby modify the osmotic pressure, allowing $N_{\rm s}$ to tune separately the equilibrium swelling and the crease threshold. This framework captures the stability boundary across solvent polymerization degree and network elasticity. These results identify polymeric solvents as active thermodynamic-mechanical regulators of swelling-induced surface. △ Less

Submitted 22 April, 2026; originally announced April 2026.

Stabilization of zigzag order in NiPS$_3$ via positive biquadratic interaction

Authors: Qiang Luo, Shuhang Yang, Xiaoying Wang, Mengdong Li, Zhengyu Jiang, Chunlan Ma, Yan Zhu

Abstract: Despite extensive research, the precise spin Hamiltonian of the van der Waals antiferromagnet NiPS$_3$ -- which hosts a zigzag-ordered ground state -- remains debated. While consensus has emerged on ferromagnetic nearest-neighbor ($J_1$) and antiferromagnetic third-nearest-neighbor ($J_3$) Heisenberg interactions, recent studies suggest a biquadratic ($B$) exchange term may also play a role, thoug… ▽ More Despite extensive research, the precise spin Hamiltonian of the van der Waals antiferromagnet NiPS$_3$ -- which hosts a zigzag-ordered ground state -- remains debated. While consensus has emerged on ferromagnetic nearest-neighbor ($J_1$) and antiferromagnetic third-nearest-neighbor ($J_3$) Heisenberg interactions, recent studies suggest a biquadratic ($B$) exchange term may also play a role, though its estimated magnitude varies widely. To address this controversy, we perform density functional theory calculations and extract a positive biquadratic interaction with $B/J_3 \approx 0.44$. Within the minimal $J_1$-$J_3$-$B$ model, we show that these parameters naturally stabilize zigzag ordering using minimally augmented spin-wave theory. Density-matrix renormalization group calculations further validate our extracted parameters as a reasonable description of the ground state. Although fully resolving the spin Hamiltonian of NiPS$_3$ requires further investigation, our findings provide new insights into its biquadratic interaction. △ Less

Submitted 1 August, 2026; v1 submitted 26 March, 2026; originally announced March 2026.

Comments: 11+11 pages, 8+2 figures

Journal ref: Phys. Rev. B 114, 034426 (2026)

Electrochemical and thermal control of continuous phase transitions in P2-NaxNi1/3Mn2/3O2

Authors: Dylan A. Edelman, John Cattermull, Jue Liu, Zhelong Jiang, Hari Ramachandran, Edward Mu, Cheng Li, Anton Van der Ven, Katherine J. Harmon, William C. Chueh

Abstract: Sodium layered oxides often undergo phase transformations involving ordering or disordering of Na+ upon desodiation, i.e., when cycled as a battery electrode. Accurately characterizing these phases is crucial for understanding functional properties, such as chemical diffusivity. In this work, we reveal that Na+-vacancy (dis)ordering in a layered oxide is intrinsically coupled to symmetry-changing… ▽ More Sodium layered oxides often undergo phase transformations involving ordering or disordering of Na+ upon desodiation, i.e., when cycled as a battery electrode. Accurately characterizing these phases is crucial for understanding functional properties, such as chemical diffusivity. In this work, we reveal that Na+-vacancy (dis)ordering in a layered oxide is intrinsically coupled to symmetry-changing phase transformations of the host structure. We examine the low-symmetry orthorhombic unit cell of P2-NaxNi1/3Mn2/3O2 (NNM) using both neutron and X-ray diffraction. Specifically, special sodium stoichiometries (x = 2/3 and 1/2) exhibit concomitant Na+-vacancy ordering and an orthorhombic distortion from the parent hexagonal unit cell. We then demonstrate that electrochemical desodiation drives symmetry-changing transformations in NNM that are linked to Na+-vacancy (dis)ordering, with evidence of second-order behavior observed near x = 2/3. Variable-temperature synchrotron X-ray diffraction further clarifies the coupling between Na+-vacancy disordering and orthorhombic-to-hexagonal phase transitions in NNM. Surprisingly, the temperature-driven phase transitions at x = 2/3 and 1/2 differ in character, appearing second-order and first-order, respectively. Our analysis of the phase transitions in NNM has fundamental consequences for sodium chemical diffusivity in the vicinity of the ordered phases and leads to design principles for modifying phase transition behavior in the broader class of intercalation electrodes. △ Less

Submitted 27 July, 2026; v1 submitted 23 March, 2026; originally announced March 2026.

Comments: Main text: 25 pages, 6 figures and SI: 36 pages, 18 figures

Flat-Band Generation in InAs/GaSb Quantum Wells through Vertically Engineered Heterostructures

Authors: Zachery A. Enderson, Jiyuan Fang, Wei-Chen Wang, Li Xiang, Mykhaylo Ozerov, Dmitry Smirnov, Zhigang Jiang, Samuel D. Hawkins, Aaron J. Muhowski, John F. Klem, Wei Pan

Abstract: Quantum materials constitute a novel category of substances wherein quantum effects and electron-electron (e-e) interactions give rise to unforeseen phenomena on a macroscopic scale. Of particular interest within the realm of quantum materials are flat bands, which promote heavy conduction electrons and enhance e-e correlation effects. While the engineering of such flat bands has been demonstrated… ▽ More Quantum materials constitute a novel category of substances wherein quantum effects and electron-electron (e-e) interactions give rise to unforeseen phenomena on a macroscopic scale. Of particular interest within the realm of quantum materials are flat bands, which promote heavy conduction electrons and enhance e-e correlation effects. While the engineering of such flat bands has been demonstrated in graphene and two-dimensional transition metal dichalcogenides moiré superlattices and in lithography defined semiconductor moiré superlattices, conventional tear-and-stack fabrication methods face challenges due to inevitable twist-angle disorder, strain, and relaxation effects, leading to issues with reproducibility and scalability. Here, we explore the creation and modification of flat bands through vertically engineered III-V semiconductor heterostructures, without the need for twisting. These artificial quantum materials offer a reproducible and scalable means for producing high-quality flat-band materials via molecular beam epitaxy growth. Our investigation includes magnetotransport and infrared magneto-spectroscopy studies of quad-layer InAs/GaSb quantum wells, accompanied by k*p band structure calculations, which illustrate the flattening of bands in vertically designed heterostructures. △ Less

Submitted 26 March, 2026; v1 submitted 16 March, 2026; originally announced March 2026.

Comments: 12 pages, 6 figures

Magnetic anisotropic pinning and symmetric breaking induced by interfacial coupling in topological-like ruthenate superlattices

Authors: Zhongyuan Jiang, Zhiwei Zhang, Kesen Zhao, Wenjie Meng, Yuanyuan Zhao, Yubin Hou, Zhangzhang Cui, Jian Zhang, Zheling Shan, Haoliang Huang, Qingyou Lu, Yalin Lu

Abstract: Interfacial engineering enables various emergent effects such as spin reorientations and transport anisotropy. Noncollinear spin textures are essential for realizing many emergent quantum transport phenomena. However, driving such spin structures requires precise control of the interfacial magnetic coupling in complex oxide heterostructures. Here, by utilizing competing exchange interactions at th… ▽ More Interfacial engineering enables various emergent effects such as spin reorientations and transport anisotropy. Noncollinear spin textures are essential for realizing many emergent quantum transport phenomena. However, driving such spin structures requires precise control of the interfacial magnetic coupling in complex oxide heterostructures. Here, by utilizing competing exchange interactions at the interface between ferromagnetic metal SrRuO3 and ferromagnetic insulator LaCoO3, we discovered a noncollinear spin configuration in SrRuO3 sublayers. Magnetic stripes were induced by out-of-plane rather than in-plane magnetic fields, indicating strong anisotropy pinning in our superlattices. The observed magneto-transport anisotropy is well explained by our proposed spin configurations, accounting for contributions from both bulk and interface of the SrRuO3 layers. More interestingly, magnetic skymionic textures were absent even at high magnetic fields. The interfacial exchange interaction overwhelms the Dzyaloshinskii-Moriya interaction (DMI) that stabilizes skyrmions, featuring a higher exchange coupling energy than that for the topological spin textures. Our work highlights the potential of interfacial engineering in tuning the spintronic properties by designing proper interfacial interactions. △ Less

Submitted 25 February, 2026; originally announced February 2026.

Comments: 14 pages, 5 figures

g4chargeit: Geant4-based kinetic Monte Carlo simulations of charging in dielectric materials

Authors: Kush P. Gandhi, Advik D. Vira, William M. Farrell, Nikolai Simonov, Alvaro Romero-Calvo, Thomas M. Orlando, Phillip N. First, Zhigang Jiang

Abstract: We present g4chargeit, a kinetic Monte Carlo framework built on Geant4 for self-consistent simulation of time-dependent electrostatic charging in dielectric materials. The model explicitly incorporates stochastic particle transport and scattering processes using validated Geant4 cross-sections, while self-consistently evolving the electric potential and field. As a representative application, we… ▽ More We present g4chargeit, a kinetic Monte Carlo framework built on Geant4 for self-consistent simulation of time-dependent electrostatic charging in dielectric materials. The model explicitly incorporates stochastic particle transport and scattering processes using validated Geant4 cross-sections, while self-consistently evolving the electric potential and field. As a representative application, we simulate the charging of regolith grains under average dayside conditions on the Moon. The surface of the Moon, in addition to other airless planetary bodies, are regularly exposed to solar ultraviolet photons and solar-wind plasma, creating a radiation environment in which electrostatic interactions among regolith grains become significant. Until now, simulations of regolith charging have often relied on analytical approximations that oversimplify grain geometry and interaction mechanisms. Our Geant4-based simulations reveal charge accumulation within intergrain micro-cavities, leading to repulsive electrostatic forces consistent with experimental observations. The framework establishes a multiscale approach that links microscopic scattering events to the continuity equation of surface charge density and to the formation of macroscopic surface charge patches in complex grain geometries. Although demonstrated here for planetary regolith, the method is general and applicable to a broad range of dielectric charging problems. The code is openly available at https://github.com/kgandhi63/g4chargeit.git. △ Less

Submitted 19 February, 2026; originally announced February 2026.

Direct nanoscale mapping of band alignment in single-layer semiconducting lateral heterojunctions

Authors: Chakradhar Sahoo, Suman Kumar Chakraborty, A. Kousika, Alfred J. H. Jones, Manas Sharma, Thomas S. Nielsen, Zhihao Jiang, Ihsan A. Kolasseri, Subhadip Das, Matthew D. Watson, Cephise Cacho, Kenji Watanabe, Takashi Taniguchi, Yong P. Chen, Tony F. Heinz, Ananth Govind Rajan, Prasana K. Sahoo, Søren Ulstrup

Abstract: Atomic-scale control over band alignment in single-layer lateral heterostructures (LHSs) of dissimilar transition metal dichalcogenides (TMDCs) is critical for nextgeneration electronic, optoelectronic, and quantum technologies. However, direct experimental access to interfacial electronic states with nanometer precision remains a significant challenge. Here, we employ angle-resolved photoemission… ▽ More Atomic-scale control over band alignment in single-layer lateral heterostructures (LHSs) of dissimilar transition metal dichalcogenides (TMDCs) is critical for nextgeneration electronic, optoelectronic, and quantum technologies. However, direct experimental access to interfacial electronic states with nanometer precision remains a significant challenge. Here, we employ angle-resolved photoemission spectroscopy with nanoscale spatial resolution (nanoARPES) to directly map the epitaxial alignment and valence band evolution across MoSe2-WSe2 LHSs. By combining nanoARPES with spatially resolved photoluminescence, we correlate the evolution of the valence band maximum and exciton features across both atomically sharp and compositionally graded diffusive interfaces. We identified type-II band alignments governed by both material composition and interstitial-induced modifications of band offsets, in close agreement with density functional theory calculations. These results reveal fundamental mechanisms of electronic structure modulation at 1D TMDC heterointerfaces and provide a robust platform for tailored band engineering in van der Waals materials. △ Less

Submitted 3 February, 2026; originally announced February 2026.

Direct Observation of Unidirectional Density Wave and Band splitting in a Single-Domain Trilayer Nickelate Pr$_4$Ni$_3$O$_{10}$

Authors: Zhicheng Jiang, Enkang Zhang, Yuxin Wang, Zhengtai Liu, Jishan Liu, Runfeng Zhang, Xinnuo Zhang, Wenchuan Jing, Yu Huang, Qi Jiang, Mao Ye, Kun Jiang, Jun Zhao, Dawei Shen, Donglai Feng

Abstract: Unraveling the interplay between density-wave (DW) instabilities and multi-orbital physics is critical for understanding superconductivity in Ruddlesden-Popper nickelates, yet intrinsic electronic features have been persistently obscured by material inhomogeneity and thus the multi-domain averaging effect. Here, we employ micro-focused angle-resolved photoemission spectroscopy ($μ$-ARPES) on singl… ▽ More Unraveling the interplay between density-wave (DW) instabilities and multi-orbital physics is critical for understanding superconductivity in Ruddlesden-Popper nickelates, yet intrinsic electronic features have been persistently obscured by material inhomogeneity and thus the multi-domain averaging effect. Here, we employ micro-focused angle-resolved photoemission spectroscopy ($μ$-ARPES) on single-domain Pr$_4$Ni$_3$O$_{10}$ to disentangle the complex hierarchy of intrinsic and back-folded bands, explicitly identifying the electronic states driving the DW phase transition. We provide decisive spectroscopic evidence that the low-energy reconstruction is governed by inter-orbital nesting between the $α$ and $β$ bands. Specifically, we resolve a orbital-dependent gap of $\sim44$ meV on the $α$ pocket, a value quantitatively consistent with prior measurements, unifying previously conflicting experimental reports regarding the locus and magnitude of the DW gap. Furthermore, we reveal strong orbital-selective mass renormalization in the $d_{z^2}$ states and successfully resolve the long-sought intrinsic trilayer $β$-band splitting, establishing a critical lower bound for the outer-layer hopping. These results define a coherent microscopic fingerprint for the trilayer nickelates, identifying the specific nesting channels and correlation effects that underpin the phase diagram. △ Less

Submitted 2 February, 2026; originally announced February 2026.

Comments: 10 pages,5 figures

Silicon Driven Facet Regulation Enables Tunable Micro-Diamond Architectures in Liquid Ga In

Authors: Zhi Jiang, Xueying Zhang, António José Silva Fernandes, Marco Peres, Gil Gonçalves

Abstract: We report an ambient pressure liquid metal assisted CVD strategy that enables shape programmable growth of micro scale diamond by coupling liquid metl Ga In with ferrocene (Fe(C5H5)2) as an carbon precursor, nanodiamond seeds, and nanosilicon. Building on liquid metal diamond synthesis, this approach pushes liquid metal growth toward a low temperature (900 °C, 1 atm) while enabling single crystal… ▽ More We report an ambient pressure liquid metal assisted CVD strategy that enables shape programmable growth of micro scale diamond by coupling liquid metl Ga In with ferrocene (Fe(C5H5)2) as an carbon precursor, nanodiamond seeds, and nanosilicon. Building on liquid metal diamond synthesis, this approach pushes liquid metal growth toward a low temperature (900 °C, 1 atm) while enabling single crystal diamonds to be scaled from ~10 μm to several tens of micrometers with well developed faceting. Ferrocene decomposition supplies a sustained interfacial carbon flux that is captured and redistributed by the Ga In melt toward seed rich liquid solid interfaces. Defect rich nanodiamond provides the crystallographic template required for reliable sp3 nucleation despite the intrinsically low carbon solubility of Ga In. Nanosilicon plays a distinct, complementary role by tuning interfacial kinetics and facet competition, enabling deliberate control of crystal habit: cubic (~10 μm), truncated tetrahedral, and fully faceted octahedral diamonds are reproducibly obtained by adjusting the nanosilicon:nanodiamond ratio, with octahedral crystals reaching ~50 μm. Importantly, crystal size is further scaled by regulating hydrogen flow: lowering the H2 rate increases net carbon retention at the liquid metal interface, raises effective supersaturation, and accelerates diamond deposition. Together, habit control (via nanosilicon: nanodiamond) and size scaling (via H2 flow) establish a practical route silicon driven facet regulation and size under ambient pressure, offering a pathway to tunable micro sized single crystal diamonds under mild conditions. △ Less

Submitted 28 January, 2026; originally announced January 2026.

Comments: 20 pages, 6 figures

Unusual Dual Flat Bands and two-dimensional Dirac-node Arc State in Kagome Metal Ni3In2S2

Authors: Bo Liang, Yichen Liu, Jie Pang, Hanbin Deng, Taimin Miao, Wenpei Zhu, Neng Cai, Tiantian Zhang, Jiayu Liu, Zhicheng Jiang, Zhanfeng Liu, Hongen Zhu, Yuliang Li, Tongrui Li, Mingkai Xu, Hao Chen, Xiaolin Ren, Chaohui Yin, Yingjie Shu, Yiwen Chen, Yu-Tian Zhang, Zhengtai Liu, Dawei Shen, Mao Ye, Fengfeng Zhang , et al. (14 additional authors not shown)

Abstract: Kagome materials are at the frontier of condensed matter physics. An ideal kagome lattice features only one geometrically frustrated flat band spanning the entire momentum space and a single Dirac cone at the Brillouin-zone corners. However, for the first time, here we observe unusual flat-band and Dirac physics in the newly discovered "322" kagome material Ni3In2S2 by combining high-resolution sy… ▽ More Kagome materials are at the frontier of condensed matter physics. An ideal kagome lattice features only one geometrically frustrated flat band spanning the entire momentum space and a single Dirac cone at the Brillouin-zone corners. However, for the first time, here we observe unusual flat-band and Dirac physics in the newly discovered "322" kagome material Ni3In2S2 by combining high-resolution synchrotron- and laser-based angle-resolved photoemission spectroscopy with a micro-focused beam, scanning tunneling microscopy, and first-principles calculations. We resolve two distinct electronic flat-band states located in close proximity to the Fermi level: a robust Topological Surface Flat Band at ~40 meV below the Fermi level on the Sulfur-terminated surface, originating from weak topological insulator states, and a kagome lattice-derived flat band at ~100 meV binding energy with an ultranarrow bandwidth (~5 meV). Instead of the single Dirac cone, the Indium-terminated surface hosts a rare two-dimensional Dirac-node arc state, where the gapless Dirac nodes extend along an open one-dimensional line crossing the Brillouin-zone boundary, exhibiting sharp linear dispersion, exceptionally high Fermi velocity, and pronounced circular dichroism. These findings establish Ni3In2S2 as a unique topological kagome metal in which multiple flat-band states of different physical origin coexist with an unusual Dirac-node arc, opening an avenue for discovering flat-band--driven and topology-enabled quantum phenomena. △ Less

Submitted 26 January, 2026; originally announced January 2026.

Comments: 26 pages, 4 figures

Electric-Switchable Chiral Magnons in PT-Symmetric Antiferromagnets

Authors: Jinyang Ni, Congzhe Yan, Peiyuan Cui, Zhijun Jiang, Yuanjun Jin, Guoqing Chang

Abstract: The magnons in antiferromagnetic insulators (AFIs) exhibit dual chirality, each carrying opposite spin angular momentum. However, in PT-symmetric AFIs, the magnon bands remain degenerate. In this work, we introduce a new class of PT-preserving AFIs in which the giant chiral splitting of magnons can be induced and controlled by an external electric field. Unlike conventional cases, such AFIs host a… ▽ More The magnons in antiferromagnetic insulators (AFIs) exhibit dual chirality, each carrying opposite spin angular momentum. However, in PT-symmetric AFIs, the magnon bands remain degenerate. In this work, we introduce a new class of PT-preserving AFIs in which the giant chiral splitting of magnons can be induced and controlled by an external electric field. Unlike conventional cases, such AFIs host a hidden dipole coupled to the antiferromagnetic order, which allows an external electric field to break the magnon sublattice symmetry and thereby largely lift the band degeneracy. Group theoretical analysis identifies the possible magnetic layer groups, while first-principles calculations and spin-wave theory reveal band splittings up to 20meV in Cr2CCl2 and Cr2CBr2 under the electric field of 0.2 V/Å, corresponding to an effective magnetic field of 200T. In addition, the electrically controlled magnon chiral splitting enables reversible switching of magnon-mediated spin currents. These findings open a new route toward nonvolatile spintronics based on magnons. △ Less

Submitted 22 May, 2026; v1 submitted 22 January, 2026; originally announced January 2026.

Imaging Intermediate Melting Phases of Dual Magnetic-Field-Stabilized Wigner Crystals

Authors: Chaofei Liu, Jianwang Zhou, Wenao Liao, Zeyu Jiang, Chao Zhang, Tingfei Guo, Tianyou Zhai, Wenhao Zhang, Ying-Shuang Fu, Qi-Kun Xue

Abstract: The competition between Coulomb repulsion and kinetic energy in correlated systems can allow electrons to crystallize into Wigner solids. Despite researches across diverse two-dimensional Wigner platforms, the microscopic melting processes through possible intermediate phases remains largely unknown. Here, we present the visualization of electron-lattice melting in monolayer VCl3 on graphite, wher… ▽ More The competition between Coulomb repulsion and kinetic energy in correlated systems can allow electrons to crystallize into Wigner solids. Despite researches across diverse two-dimensional Wigner platforms, the microscopic melting processes through possible intermediate phases remains largely unknown. Here, we present the visualization of electron-lattice melting in monolayer VCl3 on graphite, where two Wigner crystals coexist with markedly different critical temperatures Tc and lattice periods as stabilized by high magnetic field. One Wigner crystal possesses both record-high Tc and electron density, and undergoes melting through an intermediate nematic phase upon decreasing magnetic field. In contrast, the other Wigner crystal with a lower Tc yields a different intermediate phase during melting, exhibiting an anomalous electron liquid with an energy-independent modulation period. First-principles calculations corroborate the band-selective occupations of interface-transferred electrons in the formation of dual Wigner crystals. Our atomically resolved intermediate phases provide crucial insights into the microscopic melting pathways of Wigner crystals, enabling a phase diagram parameterized by both quantum and thermal fluctuations. △ Less

Submitted 4 January, 2026; originally announced January 2026.

Comments: 15 pages, 5 figures

Hilbert space signatures of non-ergodic glassy dynamics

Authors: Aleksey Lunkin, Nicole S. Ticea, Shashwat Kumar, Connie Miao, Jaehong Choi, Mohammed Alghadeer, Ilya Drozdov, Dmitry Abanin, Amira Abbas, Rajeev Acharya, Laleh Beni, Georg Aigeldinger, Ross Alcaraz, Sayra Alcaraz, Markus Ansmann, Frank Arute, Kunal Arya, Walt Askew, Nikita Astrakhantsev, Juan Atalaya, Ryan Babbush, Brian Ballard, Joseph C. Bardin, Hector Bates, Andreas Bengtsson , et al. (270 additional authors not shown)

Abstract: Disorder in quantum many-body systems can drive transitions between ergodic and non-ergodic phases, yet the nature--and even the existence--of these transitions remains intensely debated. Using a two-dimensional array of superconducting qubits, we study an interacting spin model at finite temperature in a disordered landscape, tracking dynamics both in real space and in Hilbert space. Over a broad… ▽ More Disorder in quantum many-body systems can drive transitions between ergodic and non-ergodic phases, yet the nature--and even the existence--of these transitions remains intensely debated. Using a two-dimensional array of superconducting qubits, we study an interacting spin model at finite temperature in a disordered landscape, tracking dynamics both in real space and in Hilbert space. Over a broad disorder range, we observe an intermediate non-ergodic regime with glass-like characteristics: physical observables become broadly distributed and some, but not all, degrees of freedom are effectively frozen. The Hilbert-space return probability shows slow power-law decay, consistent with finite-temperature quantum glassiness. In the same regime, we detect the onset of a finite Edwards-Anderson order parameter and the disappearance of spin diffusion. By contrast, at lower disorder, spin transport persists with a nonzero diffusion coefficient. Our results show that there is a transition out of the ergodic phase in two-dimensional systems. △ Less

Submitted 15 April, 2026; v1 submitted 3 January, 2026; originally announced January 2026.

Observation of disorder-induced superfluidity

Authors: Nicole Ticea, Elias Portoles, Eliott Rosenberg, Alexander Schuckert, Aaron Szasz, Bryce Kobrin, Nicolas Pomata, Pranjal Praneel, Connie Miao, Shashwat Kumar, Ella Crane, Ilya Drozdov, Yuri Lensky, Sofia Gonzalez-Garcia, Thomas Kiely, Dmitry Abanin, Amira Abbas, Rajeev Acharya, Laleh Aghababaie Beni, Georg Aigeldinger, Ross Alcaraz, Sayra Alcaraz, Markus Ansmann, Frank Arute, Kunal Arya , et al. (277 additional authors not shown)

Abstract: The emergence of states with long-range correlations in a disordered landscape is rare, as disorder typically suppresses the particle mobility required for long-range coherence. But when more than two energy levels are available per site, disorder can induce resonances that locally enhance mobility. Here we explore phases arising from the interplay between disorder, kinetic energy, and interaction… ▽ More The emergence of states with long-range correlations in a disordered landscape is rare, as disorder typically suppresses the particle mobility required for long-range coherence. But when more than two energy levels are available per site, disorder can induce resonances that locally enhance mobility. Here we explore phases arising from the interplay between disorder, kinetic energy, and interactions on a superconducting processor with qutrit readout and control. Compressibility measurements distinguish an incompressible Mott insulator from surrounding compressible phases and reveal signatures of glassiness, reflected in non-ergodic behavior. Spatially-resolved two-point correlator measurements identify regions of the phase diagram with a non-vanishing condensate fraction. We also visualize the spectrum by measuring the dynamical structure factor. A linearly-dispersing phonon mode materializes in the superfluid, appearing even when disorder is introduced to the clean Mott insulator. Our results provide strong experimental evidence for disorder-induced superfluidity. △ Less

Submitted 3 February, 2026; v1 submitted 24 December, 2025; originally announced December 2025.

Comments: Supplement updated

Autoregressive Neural Network Extrapolation of Quantum Spin Dynamics Across Time and Space

Authors: Hubert Pugzlys, Shreyas Varude, Sam Dillon, Huy Tran, Ta Tang, Zhe Jiang, Xuzhe Ying, Chunjing Jia

Abstract: Understanding the dynamical response of quantum materials is central to revealing their microscopic properties, yet access to long-time and large-scale dynamics remains severely limited by rapidly growing computational costs and entanglement, particularly in gapless systems. Here we introduce an autoregressive machine-learning framework that enables the extrapolation of dynamical spin correlations… ▽ More Understanding the dynamical response of quantum materials is central to revealing their microscopic properties, yet access to long-time and large-scale dynamics remains severely limited by rapidly growing computational costs and entanglement, particularly in gapless systems. Here we introduce an autoregressive machine-learning framework that enables the extrapolation of dynamical spin correlations in both time and space beyond the reach of conventional numerical methods. Trained on time-dependent density matrix renormalization group simulations of the gapless XXZ model, our approach is benchmarked against exact solutions available for this analytically solvable system. Combined with physics-informed spatial extension, multi-layer perceptron model using ReLU activation functions has been shown to be superior than convolutional neural networks and linear regressions for longer time extrapolation. Perturbation study of error accumulation further demonstrates that our autoregressive neural network extrapolations are highly robust to perturbations, suggesting stable and reliable predictions. This work establishes a new paradigm for studying the dynamics of gapless quantum many-body systems, in which machine learning extends and complements the capabilities of state-of-the-art numerical approaches. △ Less

Submitted 15 December, 2025; originally announced December 2025.

Comments: 15 pages, 5 figures

Ferroelectric Switchable Topological Magnon Hall Effect in Type-I Multiferroics

Authors: Quanchao Du, Jinlian Lu, Xueqing Wan, Zhenlong Zhang, Zhijun Jiang

Abstract: Electric control of magnetism at room temperature is crucial for developing next-generation, low-power spintronic devices. However, the intrinsic incompatibility between ferroelectricity and magnetism in crystal symmetry, along with the absence of strong magnetoelectric coupling mechanisms, continues to pose major challenges. In this work, we propose a general theoretical framework for magnon mani… ▽ More Electric control of magnetism at room temperature is crucial for developing next-generation, low-power spintronic devices. However, the intrinsic incompatibility between ferroelectricity and magnetism in crystal symmetry, along with the absence of strong magnetoelectric coupling mechanisms, continues to pose major challenges. In this work, we propose a general theoretical framework for magnon manipulation based on ferroelectric polarization switching in two-dimensional multiferroics. Taking monolayer multiferroics $\mbox{Ti}_{2}\mbox{F}_{3}$ as an example, our calculations demonstrate that ferroelectric switching can significantly modulate spin exchanges, thereby enabling nonvolatile and reversible electric control of the magnons. More importantly, the ferroelectric polarization reversal leads to a sign change in the Berry curvature, ensuring effective control over the valley Hall and nonlinear Hall response of magnons. This study provides a new way for realizing low-power and electrically controllable magnonic devices. △ Less

Submitted 21 November, 2025; originally announced November 2025.

Comments: 15 pages, 4 figures

Journal ref: Appl. Phys. Lett. 128, 152901 (2026)

Quantifying and minimizing dissipation in a non-equilibrium phase transition

Authors: Yuejun Shen, Zhiqiao Jiang, Yunfan Huang, Brittany M. Cleary, Yixing Jiang, Grant M. Rotskoff, Aaron M. Lindenberg

Abstract: In a finite-time continuous phase transition, topological defects emerge as the system undergoes spontaneous symmetry breaking. The Kibble-Zurek mechanism predicts how the defect density scales with the quench rate. During such processes, dissipation also arises as the system fails to adiabatically follow the control protocol near the critical point. Quantifying and minimizing this dissipation is… ▽ More In a finite-time continuous phase transition, topological defects emerge as the system undergoes spontaneous symmetry breaking. The Kibble-Zurek mechanism predicts how the defect density scales with the quench rate. During such processes, dissipation also arises as the system fails to adiabatically follow the control protocol near the critical point. Quantifying and minimizing this dissipation is fundamentally relevant to nonequilibrium thermodynamics and practically important for energy-efficient computing and devices. However, there are no prior experimental measurements of dissipation, or the optimization of control protocols to reduce it in many-body systems. In addition, it is an open question to what extent dissipation is correlated with the formation of defects. Here, we directly measure the dissipation generated during the voltage-driven Freedericksz transition of a liquid crystal with a sensitivity equivalent to a ~10 nanokelvin temperature rise. We observe Kibble-Zurek scaling of dissipation and its breakdown, both in quantitative agreement with existing theoretical works. We further implement a fully automated in-situ optimization approach that discovers more optimal driving protocols, reducing dissipation by a factor of three relative to a simple linear protocol. △ Less

Submitted 16 November, 2025; originally announced November 2025.

Electro-optic effects in some sliding ferroelectrics

Authors: Xueqing Wan, Zhenlong Zhang, Charles Paillard, Jinyang Ni, Lei Zhang, Zhijun Jiang, Laurent Bellaiche

Abstract: Sliding ferroelectrics, which exhibit out-of-plane polarization arising from specific stacking rather than conventional ionic displacements, are new types of ferroelectrics whose underdeveloped physics needs to be explored. Here, we investigate the electro-optic (EO) response of these materials using first-principles calculations, focusing on ZrI$_{2}$ as a prototype. We reveal that, contrary to c… ▽ More Sliding ferroelectrics, which exhibit out-of-plane polarization arising from specific stacking rather than conventional ionic displacements, are new types of ferroelectrics whose underdeveloped physics needs to be explored. Here, we investigate the electro-optic (EO) response of these materials using first-principles calculations, focusing on ZrI$_{2}$ as a prototype. We reveal that, contrary to conventional ferroelectrics, the EO effect in ZrI$_{2}$ is dominated by its electronic contribution rather than the ionic one, which promises faster EO responses. Furthermore, both biaxial and uniaxial strains significantly enhance this response, and a universal-like linear relationship between the band gap and such response is discovered. We also report a large elasto-optic coefficient that is independent of biaxial strain. Similar large linear EO coefficients and properties are found in other sliding ferroelectrics, including different zirconium dihalides, as well as BN and BP bilayers. These findings highlight sliding ferroelectrics as highly promising candidates for ultrafast nonlinear optical devices and reveal unusual mechanisms. △ Less

Submitted 17 October, 2025; v1 submitted 4 October, 2025; originally announced October 2025.

Comments: 7 pages, 4 figures

Journal ref: Phys. Rev. B 112, L140102 (2025)

Enabling full localization of qubits and gates with a multi-mode coupler

Authors: Zhongyi Jiang, Simon Geisert, Sören Ihssen, Ioan M. Pop, Mohammad H. Ansari

Abstract: Tunable couplers are a key building block of superconducting quantum processors, enabling high on-off ratios for two-qubit entangling interactions. While qubit-qubit interaction can be turned off, residual wavefunctions delocalize single-qubit excitations over the device, yielding weak effective couplings that manifest as unintended crosstalk. Moreover, conventional single-mode couplers lack indep… ▽ More Tunable couplers are a key building block of superconducting quantum processors, enabling high on-off ratios for two-qubit entangling interactions. While qubit-qubit interaction can be turned off, residual wavefunctions delocalize single-qubit excitations over the device, yielding weak effective couplings that manifest as unintended crosstalk. Moreover, conventional single-mode couplers lack independent control over interactions in the one- and two-excitation manifolds, leading to unitary errors such as leakage during gate operations. Here, we propose a multi-mode tunable coupler that enforces complete localization, yielding near-perfect qubit isolation at the decoupled point. We further show that the additional degrees of freedom in the coupler enable independent and nonlinear control of effective interactions across distinct excitation manifolds, with large on-off ratios. This architecture provides a new route toward the next generation of couplers for scalable and high-fidelity gate operations in superconducting quantum processors. △ Less

Submitted 20 February, 2026; v1 submitted 30 September, 2025; originally announced September 2025.

Comments: New simulations added. Texts updated

Spatiotemporal Raman Probing of Molecular Transport in sub-2-nm Plasmonic Quasi-2D Nanochannels

Authors: Haoran Liu, Zihe Jiang, Zhiwei Hu, Banghuan Zhang, Tao He, Xiaohui Dong, Chaowei Sun, Jun Tian, Wei Jiang, Huatian Hu, Wen Chen, Hongxing Xu

Abstract: Capturing molecular dynamics in nanoconfined channels with high spatiotemporal resolution is a key challenge in nanoscience, crucial for advancing catalysis, energy conversion, and molecular sensing. Bottom-up ultrathin plasmonic nanogaps, such as nanoparticle-on-mirror (NPoM) structures, are ideal for ultrasensitive probing due to their extreme light confinement, but their perceived sealed geomet… ▽ More Capturing molecular dynamics in nanoconfined channels with high spatiotemporal resolution is a key challenge in nanoscience, crucial for advancing catalysis, energy conversion, and molecular sensing. Bottom-up ultrathin plasmonic nanogaps, such as nanoparticle-on-mirror (NPoM) structures, are ideal for ultrasensitive probing due to their extreme light confinement, but their perceived sealed geometry has cast doubt on the existence of accessible transport pathways. Here, counterintuitively, we demonstrate that ubiquitous ligand-capped NPoM-type nanogaps can form a natural quasi-two-dimensional nanochannel, supporting molecular transport over unprecedented length scales ($\gtrsim5$ $μ$m) with an extreme aspect ratio ($>10^3$). Using wavelength-multiplexed Raman spectroscopy, we resolve the underlying centripetal infiltration pathway with a spatial resolving power of $\sim$20 nm. This redefines the NPoM architecture as a sensitive, \textit{in-situ}, all-in-one "transport-and-probe" platform, enabling real-time, reusable monitoring of analyte with $\sim$10$^{-11}$ M. This work establishes a versatile new platform for advancing super-resolved \textit{in-situ} molecular sensing, nanoscale physicochemical studies, and on-chip nanophotofluidics. △ Less

Submitted 30 September, 2025; originally announced September 2025.

Persistent Interfacial Topological Hall Effect Demonstrating Electrical Readout of Topological Spin Structures in Insulators

Authors: Jing Li, Huilin Lai, Andrew H. Comstock, Aeron McConnell, Bharat Giri, Yu Yun, Tianhao Zhao, Xiao Wang, Yongseong Choi, Xuemei Cheng, Jian Shen, Zhigang Jiang, Dali Sun, Wenbin Wang, Xiaoshan Xu

Abstract: Conventional topological Hall effects (THE) require conducting magnets, leaving insulating systems largely inaccessible. Here we introduce the interfacial topological Hall effect (ITHE), where the noncoplanar spin textures of insulating magnets are imprinted onto an adjacent heavy metal via the magnetic proximity effect (MPE) and detected electrically. In Pt/h-LuFeO3 bilayers, h-LuFeO3 hosts a top… ▽ More Conventional topological Hall effects (THE) require conducting magnets, leaving insulating systems largely inaccessible. Here we introduce the interfacial topological Hall effect (ITHE), where the noncoplanar spin textures of insulating magnets are imprinted onto an adjacent heavy metal via the magnetic proximity effect (MPE) and detected electrically. In Pt/h-LuFeO3 bilayers, h-LuFeO3 hosts a topological spin structure robust against high magnetic fields, arising from a 120° triangular spin lattice with small spin canting that yields nontrivial topology but minimal magnetization. This generates a giant Hall response in Pt up to 0.5% of the longitudinal resistivity and a Hall-conductivity/magnetization ratio above 2 V^{-1}, clearly distinguishable from the spin Hall Hanle effect background. Field- and temperature-dependent analysis further reveals that Pt nanoclusters inherit topological textures from h-LuFeO3 via MPE. Unlike the conventional THE narrow peak-and-dip features, ITHE in Pt/h-LuFeO3 persists across a broad magnetic field range up to 14 T, demonstrating the exceptional stability of the underlying topological spin structure. This establishes ITHE as a powerful and sensitive probe for topological magnetism in ultrathin insulating films and paves the way for new spintronic applications. △ Less

Submitted 23 April, 2026; v1 submitted 16 September, 2025; originally announced September 2025.

Journal ref: Phys. Rev. B 113, 134436 (2026)

Nonreciprocal magnons in layered antiferromagnets VPX3(X =S,Se,Te)

Authors: Quanchao Du, Zhenlong Zhang, Jinyang Ni, Zhijun Jiang, Laurent Bellaiche

Abstract: Nonreciprocal magnons, characterized by propagation with differing energies along the k and -k directions, are crucial for modern spintronics applications. However, their realization in van der Waals layered antiferromagnets remains elusive. In this letter, we report robust nonreciprocal magnon behavior in layered honeycomb antiferromagnets VPX3(X =S,Se,Te). Our results demonstrate that, in additi… ▽ More Nonreciprocal magnons, characterized by propagation with differing energies along the k and -k directions, are crucial for modern spintronics applications. However, their realization in van der Waals layered antiferromagnets remains elusive. In this letter, we report robust nonreciprocal magnon behavior in layered honeycomb antiferromagnets VPX3(X =S,Se,Te). Our results demonstrate that, in addition to their intrinsic Dzyaloshinskii-Moriya interaction (DMI), the nonreciprocity of magnons is strongly influenced by the layer number, interlayer coupling, and magnon-magnon interactions. More importantly, in such layered antiferromagnets, the magnon nonreciprocity exhibits an asymmetric periodic dependence on the Neel vector, offering a novel route for experimentally probing antiferromagnetic order parameters in the 2D limit. △ Less

Submitted 11 September, 2025; v1 submitted 8 September, 2025; originally announced September 2025.

Comments: 5 figures

Journal ref: Phys. Rev. B 112, L100408 (2025)

Surface reconstruction and orthogonal decoupling in SrAl4 and EuAl4

Authors: Tongrui Li, Leiyuan Chen, Jian Yuan, Zhengtai Liu, Yichen Yang, Zhicheng Jiang, Jianyang Ding, Jiayu Liu, Jishan Liu, Zhe Sun, Yanfeng Guo, Tong Zhang, Dawei Shen

Abstract: Surface-induced symmetry breaking in quantum materials can stabilize exotic electronic phases distinct from those in the bulk, yet its momentum-space manifestations remain elusive due to domain-averaging effects. Here, using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), we present a microscopic investigation of the electronic structures of SrAl4 and EuA… ▽ More Surface-induced symmetry breaking in quantum materials can stabilize exotic electronic phases distinct from those in the bulk, yet its momentum-space manifestations remain elusive due to domain-averaging effects. Here, using angle-resolved photoemission spectroscopy (ARPES) and scanning tunneling microscopy (STM), we present a microscopic investigation of the electronic structures of SrAl4 and EuAl4, layered tetragonal intermetallic compounds that exhibit well-characterized incommensurate charge-density-wave (CDW) transitions. Below the CDW transition temperatures, we uncover linearly dispersing electronic states and pronounced unidirectional replica bands orthogonal to the bulk CDW wave vector, evidencing the emergence of an in-plane C4 symmetry-breaking electronic order that is not dictated by the bulk incommensurate CDW. STM measurements further reveal a 1 times 2 surface reconstruction with quasi-one-dimensional modulations and half-unit-cell steps, traced to ordered 50 percent Sr/Eu vacancies, which vanish irreversibly upon thermal cycling, indicating decoupled surface and bulk orders. These findings establish SrAl4 and EuAl4 as model platforms for exploring surface-confined nematicity and emergent low-dimensional phases in quantum materials. △ Less

Submitted 4 September, 2025; originally announced September 2025.

Comments: 9 pages,4 figures

Superconductivity and Electronic Structures of Nickelate Thin Film Superstructures

Authors: Zihao Nie, Yueying Li, Wei Lv, Lizhi Xu, Zhicheng Jiang, Peng Fu, Guangdi Zhou, Wenhua Song, Yaqi Chen, Heng Wang, Haoliang Huang, Junhao Lin, Jin-Feng Jia, Dawei Shen, Peng Li, Qi-Kun Xue, Zhuoyu Chen

Abstract: Ruddlesden-Popper (RP) nickelates have emerged as a crucial platform for exploring the mechanisms of high-temperature superconductivity. However, the Fermi surface topology required for superconductivity remains elusive. Here, beyond the superconducting pure bilayer (2222) phase, we report the thin film growth and ambient-pressure superconductivity of monolayer-bilayer (1212) and bilayer-trilayer… ▽ More Ruddlesden-Popper (RP) nickelates have emerged as a crucial platform for exploring the mechanisms of high-temperature superconductivity. However, the Fermi surface topology required for superconductivity remains elusive. Here, beyond the superconducting pure bilayer (2222) phase, we report the thin film growth and ambient-pressure superconductivity of monolayer-bilayer (1212) and bilayer-trilayer (2323) superstructures, together with the absence of superconductivity in monolayer-trilayer (1313) superstructure, under identical compressive epitaxial strain. The onset superconducting transition temperatures range from 46 to 50 K, exceeding the McMillan limit. Angle-resolved photoemission spectroscopy reveals key Fermi surface differences in these atomically-engineered structures. In superconducting 1212 and 2222 films, a dispersive hole-like band ($γ^{\mathrm{II}}$) forms an underlying Fermi pocket, surrounding the Brillouin zone corner. In contrast, the top of the flat band ($γ^{\mathrm{III}}$) is observed ~70 meV below $E_\text{F}$ in the non-superconducting 1313 films. Particularly, the superconducting 2323 films host both $γ^{\mathrm{II}}$ and $γ^{\mathrm{III}}$ bands. The polarization dependence of the $γ$ bands reveals their Ni $d_{z^2}$ origin. Our findings expand the family of ambient-pressure nickelate superconductors and establish a connection between structural configuration, electronic structure, and the emergence of superconductivity in nickelates. △ Less

Submitted 13 April, 2026; v1 submitted 3 September, 2025; originally announced September 2025.

Journal ref: Nature 2026

Topological switching in bilayer magnons via electrical control

Authors: Xueqing Wan, Quanchao Du, Jinlian Lu, Zhenlong Zhang, Jinyang Ni, Lei Zhang, Zhijun Jiang, Laurent Bellaiche

Abstract: Topological magnons, quantized spin waves featuring nontrivial boundary modes, present a promising route toward lossless information processing. Realizing practical devices typically requires magnons excited in a controlled manner to enable precise manipulation of their topological phases and transport behaviors. However, their inherent charge neutrality and a high frequency nature pose a signific… ▽ More Topological magnons, quantized spin waves featuring nontrivial boundary modes, present a promising route toward lossless information processing. Realizing practical devices typically requires magnons excited in a controlled manner to enable precise manipulation of their topological phases and transport behaviors. However, their inherent charge neutrality and a high frequency nature pose a significant challenge for nonvolatile control, especially via electric means. Herein, we propose a general strategy for electrical control of topological magnons in bilayer ferromagnetic insulators. With strong spin-layer coupling, an applied vertical electric field induces an interlayer potential imbalance that modifies intralayer Heisenberg exchanges between adjacent layers. This electric-field-driven modulation competes with the bilayer's intrinsic Dzyaloshinskii-Moriya interaction, enabling the accurate tuning of the band topology and nonreciprocal dynamics of magnons. More importantly, such an electric control mechanism exhibits strong coupling with external magnetic fields, unveiling new perspectives on magnetoelectric coupling in charge-neutral quasiparticles △ Less

Submitted 31 August, 2025; originally announced September 2025.

Comments: 4 figures,

Journal ref: Phys. Rev. B 112, L100404 (2025)

Quantitative Benchmarking of Remote Excitation in Plasmonic Sensing with Enhanced Signal-to-Noise Ratio

Authors: Tao He, Haoran Liu, Zihe Jiang, Zhiwei Hu, Banghuan Zhang, Xiaohui Dong, Chaowei Sun, Wei Jiang, Jiawei Sun, Yang Li, Huatian Hu, Wen Chen, Hongxing Xu

Abstract: Remote excitation using guided optical modes -- such as waveguides, fibers, or surface waves -- offers a promising alternative to direct optical excitation for surface-enhanced Raman scattering (SERS), particularly in applications requiring reduced heating, minimal invasiveness, and on-chip integration. However, despite its widespread use, systematic comparisons between remote and direct excitatio… ▽ More Remote excitation using guided optical modes -- such as waveguides, fibers, or surface waves -- offers a promising alternative to direct optical excitation for surface-enhanced Raman scattering (SERS), particularly in applications requiring reduced heating, minimal invasiveness, and on-chip integration. However, despite its widespread use, systematic comparisons between remote and direct excitation remain limited. Here, we quantitatively benchmark both schemes by measuring power-dependent SERS responses from individual plasmonic nanogaps. We statistically analyze the maximum achievable SERS intensity before structural degradation, extract local temperatures, and evaluate signal-to-noise ratios (SNR). Our findings reveal that both remote and direct SERS share a common electric-field limit, despite exhibiting different levels of heating. This suggests that spectral evolution is primarily governed by the local electric field, which drives nanoscale atomic migration rather than excessive heating. Nonetheless, the lower heating associated with remote excitation enhances the Raman SNR by approximately 30%, improving measurement quality without compromising signal strength. This study establishes a quantitative framework for evaluating excitation strategies in plasmonic sensing, and challenges common assumptions about the role of heating in nanostructural stability under strong optical excitation. △ Less

Submitted 30 July, 2025; originally announced July 2025.

Comments: 5 figures

Ultrastable, low-error dynamic polarization encoding of deterministically generated single photons

Authors: Joscha Hanel, Zenghui Jiang, Jipeng Wang, Frederik Benthin, Tom Fandrich, Eddy Patrick Rugeramigabo, Raphael Joos, Michael Jetter, Simone Luca Portalupi, Jingzhong Yang, Michael Zopf, Peter Michler, Fei Ding

Abstract: The ability to inscribe information on single photons at high speeds is a crucial requirement for quantum applications such as quantum communication and measurement-based photonic quantum computation. Nowadays, most experimental implementations employ phase modulators in single-pass, Mach-Zehnder interferometer or Michelson interferometer configurations to encode information on photonic qubits. Ho… ▽ More The ability to inscribe information on single photons at high speeds is a crucial requirement for quantum applications such as quantum communication and measurement-based photonic quantum computation. Nowadays, most experimental implementations employ phase modulators in single-pass, Mach-Zehnder interferometer or Michelson interferometer configurations to encode information on photonic qubits. However, these approaches are intrinsically sensitive to environmental influences, limiting the achievable quantum error rates in practice. We report on the first demonstration of a polarization encoder for single-photon qubits based on a free-space Sagnac interferometer, showcasing inherent phase stability and overcoming previous error rate limitations. Telecom-wavelength single photons emitted by a quantum dot are modulated by the encoder under a repetition rate of 152 MHz. A quantum bit error rate of 0.69(2)% is achieved, marking the lowest error rate reported to date for high-speed information encoding on single photons. This work represents a key advance towards robust, scalable, and low-error quantum information processing with single photon sources. △ Less

Submitted 22 July, 2025; originally announced July 2025.

Comments: 13 pages, 4 figures

Observation of superconductivity-induced leading-edge gap in Sr-doped $\mathrm{La}_{3}\mathrm{Ni}_{2}\mathrm{O}_{7}$ thin films

Authors: Wenjie Sun, Zhicheng Jiang, Bo Hao, Shengjun Yan, Hongyi Zhang, Maosen Wang, Yang Yang, Haoying Sun, Zhengtai Liu, Dianxiang Ji, Zhengbin Gu, Jian Zhou, Dawei Shen, Donglai Feng, Yuefeng Nie

Abstract: The discovery of high-temperature superconductivity in pressurized bulk $\mathrm{La}_{3}\mathrm{Ni}_{2}\mathrm{O}_{7}$ has ignited significant interest in nickelate superconductors. Unlike cuprates, where superconductivity predominantly originates from the $\mathrm{3}d_{x^2-y^2}$ orbital, nickelates exhibit additional complexities involving contributions from the $\mathrm{3}d_{z^2}$ orbital, promp… ▽ More The discovery of high-temperature superconductivity in pressurized bulk $\mathrm{La}_{3}\mathrm{Ni}_{2}\mathrm{O}_{7}$ has ignited significant interest in nickelate superconductors. Unlike cuprates, where superconductivity predominantly originates from the $\mathrm{3}d_{x^2-y^2}$ orbital, nickelates exhibit additional complexities involving contributions from the $\mathrm{3}d_{z^2}$ orbital, prompting fundamental questions about their pairing mechanisms. Despite recent progress in stabilizing superconductivity in $\mathrm{La}_{3}\mathrm{Ni}_{2}\mathrm{O}_{7}$ thin films at ambient pressure, direct spectroscopic evidence of the superconducting gap opening remains elusive. Here, we present an in-situ angle-resolved photoemission spectroscopy study of Sr-doped superconducting $\mathrm{La}_{3}\mathrm{Ni}_{2}\mathrm{O}_{7}$ thin films. Fermi surface mapping reveals Ni-$\mathrm{3}d_{x^2-y^2}$-derived $α$ and $β$ pockets, with orbital fillings of 0.11$\pm$0.02 electrons and 0.66$\pm$0.03 holes per Ni, respectively, resulting in a total of 0.45$\pm$0.04 electrons for each Ni. These bands exhibit moderate electron correlations, characterized by a band renormalization factor of 3-4. Notably, both $α$ and $β$ bands exhibit leading-edge shifts across the superconducting transition, with gap magnitude of ~1-2 meV at Fermi momenta along the Brillouin zone diagonal and slightly away from the zone diagonal, deviating from the conventional $d_{x^2-y^2}$-wave gap structure. Additionally, the Ni-$\mathrm{3}d_{z^2}$-derived $γ$ band lies ~75 meV below the Fermi level, indicating a $\mathrm{3}d_{x^2-y^2}$-dominated fermiology in this compound. △ Less

Submitted 10 July, 2025; originally announced July 2025.

Comments: 18 pages and 5 figures

On-Device Control of Electronic Friction

Authors: Zhaokuan Yu, Jinbo Bian, Jin Wang, Zonghuiyi Jiang, Linxin Zhai, Xin Lu, Xiaofei Liu, Quanshui Zheng, Zhiping Xu

Abstract: Friction causes mechanical energy dissipation and material degradation in machinery and devices. While phononic friction is well understood via anharmonic lattice dynamics, the physics of electronic friction remains unclear due to challenges in separating electronic degrees of freedom from phononic ones in experiments and analyzing the non-equilibrium interactions between ionic movement and electr… ▽ More Friction causes mechanical energy dissipation and material degradation in machinery and devices. While phononic friction is well understood via anharmonic lattice dynamics, the physics of electronic friction remains unclear due to challenges in separating electronic degrees of freedom from phononic ones in experiments and analyzing the non-equilibrium interactions between ionic movement and electronic dynamics in theory. To tackle this problem, we construct a sliding device featuring 2D crystalline interfaces that possess ultra-smooth and minimally interacting surfaces, achieving the state of structural superlubricity with no wear and minimal friction. Using electrical and mechanical controls, we tuned the nature of interfacial electronic coupling and charge densities in materials in an on-device setting, which allows us to disentangle the electron and phonon contributions to friction. Our experimental data and theoretical analysis supported by first-principles calculations demonstrate that electronic friction can well surpass phononic contributions and dominate energy dissipation at structural superlubricity contacts. These findings offer fresh insights into the mechanism of electronic friction and promising opportunities for friction control in device applications. △ Less

Submitted 5 July, 2025; originally announced July 2025.

Data-Driven Review and Machine Learning Prediction of Diamond Vacancy Center Synthesis

Authors: Zhi Jiang, Marco Peres, Carlo Bradac, Gil Gonçalves

Abstract: Diamond and diamond color centers have become prime hardware candidates for solid state-based technologies in quantum information and computing, optics, photonics and (bio)sensing. The synthesis of diamond materials with specific characteristics and the precise control of the hosted color centers is thus essential to meet the demands of advanced applications. Yet, challenges remain in improving th… ▽ More Diamond and diamond color centers have become prime hardware candidates for solid state-based technologies in quantum information and computing, optics, photonics and (bio)sensing. The synthesis of diamond materials with specific characteristics and the precise control of the hosted color centers is thus essential to meet the demands of advanced applications. Yet, challenges remain in improving the concentration, uniform distribution and quality of these centers. Here, we perform a review and meta-analysis of some of the main diamond synthesis methods and their parameters for the synthesis of N-, Si-, Ge- and Sn-vacancy color-centers. We extract quantitative data from over 60 experimental papers and organize it in a large database (170 data sets and 1692 entries). We then use the database to train two machine learning algorithms to make robust predictions about the fabrication of diamond materials with specific properties from careful combinations of synthesis parameters. We use traditional statistical indicators to benchmark the performance of the algorithms and show that they are powerful and resource-efficient tools for researchers and material scientists working with diamond color centers and their applications. △ Less

Submitted 14 January, 2026; v1 submitted 3 July, 2025; originally announced July 2025.

Comments: 54 pages, 29 figures

A scanning resonator for probing quantum coherent devices

Authors: Jared Gibson, Zhanzhi Jiang, Angela Kou

Abstract: Superconducting resonators with high quality factors are extremely sensitive detectors of the complex impedance of materials and devices coupled to them. This capability has been used to measure losses in multiple different materials and, in the case of circuit quantum electrodynamics (circuit QED), has been used to measure the coherent evolution of multiple different types of qubits. Here, we rep… ▽ More Superconducting resonators with high quality factors are extremely sensitive detectors of the complex impedance of materials and devices coupled to them. This capability has been used to measure losses in multiple different materials and, in the case of circuit quantum electrodynamics (circuit QED), has been used to measure the coherent evolution of multiple different types of qubits. Here, we report on the implementation of a scanning resonator for probing quantum coherent devices. Our scanning setup enables tunable coherent coupling to systems of interest without the need for fabricating on-chip superconducting resonators. We measure the internal quality factor of our resonator sensor in the single-photon regime to be > 10000 and demonstrate capacitive imaging using our sensor with zeptoFarad sensitivity and micron spatial resolution at milliKelvin temperatures. We then use our setup to characterize the energy spectrum and coherence times of multiple transmon qubits with no on-chip readout circuitry. Our work introduces a new tool for using circuit QED to measure existing and proposed qubit platforms. △ Less

Submitted 27 June, 2025; originally announced June 2025.

Collision-assisted information scrambling on a configurable photonic chip

Authors: Xiao-Wen Shang, Shu-Yi Liang, Guan-Ju Yan, Xin-Yang Jiang, Zi-Ming Yin, Hao Tang, Jian-Peng Dou, Ze-Kun Jiang, Yu-Quan Peng, Xian-Min Jin

Abstract: Quantum interference and entanglement are in the core of quantum computations. The fast spread of information in the quantum circuit helps to mitigate the circuit depth. Although the information scrambling in the closed systems has been proposed and tested in the digital circuits, how to measure the evolution of quantum correlations between systems and environments remains a delicate and open ques… ▽ More Quantum interference and entanglement are in the core of quantum computations. The fast spread of information in the quantum circuit helps to mitigate the circuit depth. Although the information scrambling in the closed systems has been proposed and tested in the digital circuits, how to measure the evolution of quantum correlations between systems and environments remains a delicate and open question. Here, we propose a photonic circuit to investigate the information scrambling in an open quantum system by implementing the collision model with cascaded Mach-Zehnder interferometers. We numerically simulate the photon propagation and find that the tripartite mutual information strongly depends on the system-environment and environment-environment interactions. We further reduce the number of observables and the number of shots required to reconstruct the density matrix by designing an enhanced compressed sensing. Our results provide a reconfigurable photonic platform for simulating open quantum systems and pave the way for exploring controllable dissipation and non-Markovianity in discrete-variable photonic computing. △ Less

Submitted 19 June, 2025; originally announced June 2025.

Comments: 7 pages, 4 figures. Comments are welcome!