Showing 1–50 of 246 results for author: Li, K

Interlayer hybridization enables superconductivity in bilayer nickelates

Authors: Shilong Zhang, Meng Zhang, Qilin Luo, Zihao Tao, Hsiao-Yu Huang, Kunhao Li, Jie Li, Junchi Fu, Di-Jing Huang, Yanwu Xie, Yi Lu, Yingying Peng

Abstract: Ruddlesden-Popper nickelates offer a new route to high-temperature superconductivity beyond the cuprates and iron-pnictides. However, the electronic reorganization that enables superconductivity in bilayer nickelates remain unresolved, largely due to the difficulty of directly probing the superconducting phase. Here, we overcome this limitation by stabilizing superconducting (La,Pr)$_3$Ni$_2$O… ▽ More Ruddlesden-Popper nickelates offer a new route to high-temperature superconductivity beyond the cuprates and iron-pnictides. However, the electronic reorganization that enables superconductivity in bilayer nickelates remain unresolved, largely due to the difficulty of directly probing the superconducting phase. Here, we overcome this limitation by stabilizing superconducting (La,Pr)$_3$Ni$_2$O$_7$ thin films with a protective capping layer, thereby enabling direct spectroscopic access via X-ray absorption and resonant inelastic X-ray scattering. We resolve the evolution of in-plane and out-of-plane electronic states, spin and orbital excitations, and spin-density-waves across insulating, superconducting, and metallic regimes. Combining experimental results with theoretical analysis, we show that the in-plane $d_{x^2-y^2}$ states form an itinerant backbone, while superconductivity emerges only when coherent $d_{z^2}$-$p_z$-$d_{z^2}$ interlayer hybridization develops, accompanied by suppressed static spin order and strongly damped spin excitations. Oxygen stoichiometry and epitaxial strain both act on this interlayer channel, placing superconductivity within a narrow window of interlayer coherence and correlation strength. These findings identify the microscopic ingredients required for superconductivity in bilayer nickelates and provide a multiorbital picture of its emergence. △ Less

Submitted 16 April, 2026; originally announced April 2026.

Comments: 8 pages, 4 figures

Quasicrystal Architected Nanomechanical Resonators via Data-Driven Design

Authors: Kawen Li, Hangjin Cho, Richard Norte, Dongil Shin

Abstract: From butterfly wings to remnants of nuclear detonation, aperiodic order repeatedly emerges in nature, often exhibiting reduced sensitivity to boundaries and symmetry constraints. Inspired by this principle, a paradigm shift is introduced in nanomechanical resonator design from periodic to aperiodic structures, focusing on a special class: quasicrystals (QCs). Although soft clamping enabled by phon… ▽ More From butterfly wings to remnants of nuclear detonation, aperiodic order repeatedly emerges in nature, often exhibiting reduced sensitivity to boundaries and symmetry constraints. Inspired by this principle, a paradigm shift is introduced in nanomechanical resonator design from periodic to aperiodic structures, focusing on a special class: quasicrystals (QCs). Although soft clamping enabled by phononic stopbands has become a central strategy for achieving high-$Q_m$ nanomechanical resonators, its practical realization has been largely confined to periodic phononic crystals, where band structure engineering is well established. The potential of aperiodic architectures, however, has remained largely unexplored, owing to their intrinsic complexity and the lack of systematic approaches to identifying and exploiting stopband behavior. Here we demonstrate that soft clamping can be realized in quasicrystal architectures and that high-$Q_m$ nanomechanical resonators can be systematically achieved through a data-driven design framework. As a representative demonstration, the 12-fold QC-based resonator exhibits a quality factor $Q_m \sim 10^7$ and an effective mass of sub-nanograms at MHz frequencies, corresponding to an exceptional force sensitivity of $26.4$~aN/$\sqrt{\text{Hz}}$ compared to previous 2D phononic crystals. These results establish QCs as a robust platform for next-generation nanomechanical resonators and open a new design regime beyond periodic order. △ Less

Submitted 7 April, 2026; originally announced April 2026.

Thermal Entanglement and Out-of-Equilibrium Thermodynamics in 1D Bose gases

Authors: Julia Mathé, Nicky Kai Hong Li, Pharnam Bakhshinezhad, Giuseppe Vitagliano

Abstract: We investigate entanglement in and out of equilibrium in a one-dimensional Bose gas in its low-energy Bogoliubov regime. In this Gaussian setting, the state is fully characterized by its covariance matrix, which allows us to detect and quantify entanglement using a covariance-based framework and associated entanglement monotones. For thermal states, we determine the optimal entanglement witness ar… ▽ More We investigate entanglement in and out of equilibrium in a one-dimensional Bose gas in its low-energy Bogoliubov regime. In this Gaussian setting, the state is fully characterized by its covariance matrix, which allows us to detect and quantify entanglement using a covariance-based framework and associated entanglement monotones. For thermal states, we determine the optimal entanglement witness arising from the covariance matrix criterion and show that it has a remarkably simple mode-resolved structure: it is diagonal in the normal-mode basis and admits a simple analytic form that can be expressed as a product of only two normal-mode uncertainties. We then study out-of-equilibrium dynamics induced by unitary compression and show that entanglement can be generated even from initially separable thermal states. When the evolution is fully adiabatic, the optimal witness retains the same two-mode structure as in the thermal case. Departing from this regime, i.e., performing increasingly rapid compression, the optimal witness becomes genuinely more intricate. Our methods and results provide a unified and physically intuitive picture of how entanglement emerges and evolves in 1D quantum Bose gases, and identify an optimal witness structure relevant more broadly to the analysis of entanglement in quadratic bosonic models and its role in thermodynamic cycles. △ Less

Submitted 1 April, 2026; originally announced April 2026.

Comments: 10+14 pages, 6 figures

Two-dimensional bound excitons in the real space and Landau quantization space: a comparative study

Authors: Kunxiang Li, Yi-Xiang Wang

Abstract: The Landau quantization space is based on the respective motion of the electron and hole in a magnetic field and can provide a new route to understand the bound exciton behaviors observed in the experiments. In this paper, we study the two-dimensional exciton properties of monolayer WSe$_2$ in both the real space and Landau quantization space. Focusing on the excitons of zero center-of-mass moment… ▽ More The Landau quantization space is based on the respective motion of the electron and hole in a magnetic field and can provide a new route to understand the bound exciton behaviors observed in the experiments. In this paper, we study the two-dimensional exciton properties of monolayer WSe$_2$ in both the real space and Landau quantization space. Focusing on the excitons of zero center-of-mass momentum, we calculate its energy spectrum in both spaces, with the results agreeing well with each other. We then obtain the diamagnetic coefficients and root-mean-square radius, which are consistent with the available $s$ state data in the experiment. More importantly, in the exciton state $nl$, we find that the dominant electron-hole pair component may shift with the magnetic field and the Coulomb interactions, and reveal that the magnetic field will drive the dominant component to be the free electron-hole pair $\{n_e=n+l-1,n_h=n-1\}$, whereas the Coulomb interactions drives it to be the pair of the lower index. △ Less

Submitted 25 March, 2026; v1 submitted 23 March, 2026; originally announced March 2026.

Comments: 11 pages, 6 figures

GPUMDkit: A User-Friendly Toolkit for GPUMD and NEP

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

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

Submitted 18 March, 2026; originally announced March 2026.

Comments: 17 pages, 7 figures

Superconductivity in the A15-type V3(Os1-2xSixGex) medium-entropy alloys

Authors: Yucheng Li, Kuan Li, Lingyong Zeng, Rui Chen, Jingjun Qin, Shuangyue Wang, Huixia Luo

Abstract: Cubic A15-type superconducting alloys continue to fascinate the academic and industrial fields because they mainly support the largest market for low-temperature superconducting applications and show exotic physical properties. Medium-/high-entropy alloys (MEAs-HEAs) can be employed stably under extreme conditions due to their high mechanical hardness and excellent irradiation tolerance. Combining… ▽ More Cubic A15-type superconducting alloys continue to fascinate the academic and industrial fields because they mainly support the largest market for low-temperature superconducting applications and show exotic physical properties. Medium-/high-entropy alloys (MEAs-HEAs) can be employed stably under extreme conditions due to their high mechanical hardness and excellent irradiation tolerance. Combining with the features of the A15-type superconductor and MEAs-HEAs, we design a series of previously unreported A15-type V3(Os1-2xSixGex) (x = 0.333, 0.375, 0.425) MEA superconductors, which can be obtained by an arc melting method. Resistivity, magnetic susceptibility, and specific heat measurements indicate that all of them are type-II bulk superconductors. The superconducting transition temperature (Tc) exhibits an upward trend with the systematic reduction of Os concentration. Additionally, the upper critical field of the V3(Os0.333Si0.333Ge0.333) sample is larger than the Pauli limit, suggesting it may be robust against magnetic fields due to spin-orbit coupling induced by the heavy Os atoms. These findings not only advance our understanding of emergent phenomena in entropy-stabilized A15-type alloys but also expand the members of new superconductors. △ Less

Submitted 27 February, 2026; originally announced February 2026.

Comments: 25 pages, 5 figures

Journal ref: SCIENCE CHINA Materials, 2026

Spiral states, first-order transitions and specific heat multipeak phenomenon in $J_1$-$J_2$-$J_3$ Ising model: A Wang-Landau algorithm study

Authors: Habib Ullah, Kun Li, Haoyu Lu, Youjin Deng, Wanzhou Zhang

Abstract: The classical $J_1$-$J_2$-$J_3$ Ising model on the honeycomb lattice is important for understanding frustrated magnetic phenomena in materials such as FePS$_3$ and Ba$_2$CoTeO$_6$, where diverse phases (e.g., striped, zigzag, armchair) and magnetization plateaus have been experimentally observed. To explain the experimental results, previous mean-field studies have explored its thermal phase trans… ▽ More The classical $J_1$-$J_2$-$J_3$ Ising model on the honeycomb lattice is important for understanding frustrated magnetic phenomena in materials such as FePS$_3$ and Ba$_2$CoTeO$_6$, where diverse phases (e.g., striped, zigzag, armchair) and magnetization plateaus have been experimentally observed. To explain the experimental results, previous mean-field studies have explored its thermal phase transitions, identifying armchair phases and striped phases, but their limitations call for more reliable numerical investigations. In this work, we systematically revisit the classical $J_1$-$J_2$-$J_3$ Ising model using the Wang-Landau algorithm. We find that the armchair (AC) phase, previously reported in mean-field and experimental studies, actually coexists with the spiral (SP) phase, with their combined degeneracy reaching 20-fold (4-fold for the AC states and 16-fold for the spiral states). The phase transitions and critical exponents are studied at different interaction values. We observe first-order phase transitions, continuous phase transitions, and even the multipeak phenomenon in frustrated systems. These results clarify the nature of phases and phase transitions in frustrated Ising systems and their exponents, and additionally provide inspiration for experimental efforts to search for the spiral state and specific-heat multipeak phenomenon. △ Less

Submitted 29 December, 2025; v1 submitted 21 December, 2025; originally announced December 2025.

Comments: 12 pages, 12 figures

High-throughput validation of phase formability and simulation accuracy of Cantor alloys

Authors: Changjun Cheng, Daniel Persaud, Kangming Li, Michael J. Moorehead, Natalie Page, Christian Lavoie, Beatriz Diaz Moreno, Adrien Couet, Samuel E Lofland, Jason Hattrick-Simpers

Abstract: High-throughput methods enable accelerated discovery of novel materials in complex systems such as high-entropy alloys, which exhibit intricate phase stability across vast compositional spaces. Computational approaches, including Density Functional Theory (DFT) and calculation of phase diagrams (CALPHAD), facilitate screening of phase formability as a function of composition and temperature. Howev… ▽ More High-throughput methods enable accelerated discovery of novel materials in complex systems such as high-entropy alloys, which exhibit intricate phase stability across vast compositional spaces. Computational approaches, including Density Functional Theory (DFT) and calculation of phase diagrams (CALPHAD), facilitate screening of phase formability as a function of composition and temperature. However, the integration of computational predictions with experimental validation remains challenging in high-throughput studies. In this work, we introduce a quantitative confidence metric to assess the agreement between predictions and experimental observations, providing a quantitative measure of the confidence of machine learning models trained on either DFT or CALPHAD input in accounting for experimental evidence. The experimental dataset was generated via high-throughput in-situ synchrotron X-ray diffraction on compositionally varied FeNiMnCr alloy libraries, heated from room temperature to ~1000 °C. Agreement between the observed and predicted phases was evaluated using either temperature-independent phase classification or a model that incorporates a temperature-dependent probability of phase formation. This integrated approach demonstrates where strong overall agreement between computation and experiment exists, while also identifying key discrepancies, particularly in FCC/BCC predictions at Mn-rich regions to inform future model refinement. △ Less

Submitted 24 November, 2025; originally announced November 2025.

When Active Learning Fails, Uncalibrated Out of Distribution Uncertainty Quantification Might Be the Problem

Authors: Ashley S. Dale, Kangming Li, Brian DeCost, Hao Wan, Yuchen Han, Yao Fehlis, Jason Hattrick-Simpers

Abstract: Efficiently and meaningfully estimating prediction uncertainty is important for exploration in active learning campaigns in materials discovery, where samples with high uncertainty are interpreted as containing information missing from the model. In this work, the effect of different uncertainty estimation and calibration methods are evaluated for active learning when using ensembles of ALIGNN, eX… ▽ More Efficiently and meaningfully estimating prediction uncertainty is important for exploration in active learning campaigns in materials discovery, where samples with high uncertainty are interpreted as containing information missing from the model. In this work, the effect of different uncertainty estimation and calibration methods are evaluated for active learning when using ensembles of ALIGNN, eXtreme Gradient Boost, Random Forest, and Neural Network model architectures. We compare uncertainty estimates from ALIGNN deep ensembles to loss landscape uncertainty estimates obtained for solubility, bandgap, and formation energy prediction tasks. We then evaluate how the quality of the uncertainty estimate impacts an active learning campaign that seeks model generalization to out-of-distribution data. Uncertainty calibration methods were found to variably generalize from in-domain data to out-of-domain data. Furthermore, calibrated uncertainties were generally unsuccessful in reducing the amount of data required by a model to improve during an active learning campaign on out-of-distribution data when compared to random sampling and uncalibrated uncertainties. The impact of poor-quality uncertainty persists for random forest and eXtreme Gradient Boosting models trained on the same data for the same tasks, indicating that this is at least partially intrinsic to the data and not due to model capacity alone. Analysis of the target, in-distribution uncertainty, out-of-distribution uncertainty, and training residual distributions suggest that future work focus on understanding empirical uncertainties in the feature input space for cases where ensemble prediction variances do not accurately capture the missing information required for the model to generalize. △ Less

Submitted 21 November, 2025; originally announced November 2025.

In-Situ Growth of Halide Perovskite Single Crystals and Thin Films on Optical Fiber End Facets

Authors: Yang Yu, Kanak Kanti Bhowmik, Ruan Li, Kexin Li, Lin Zhu, Hai Xiao, Lianfeng Zhao

Abstract: Halide perovskites exhibit significant advantages for active optical components such as light emitting diodes, solar cells and photodetectors due to their excellent optoelectronic properties. Their nonlinear optical effects and other characteristics also make them suitable for integration into waveguide components, such as optical fibers, for applications like optical modulation. Although some eff… ▽ More Halide perovskites exhibit significant advantages for active optical components such as light emitting diodes, solar cells and photodetectors due to their excellent optoelectronic properties. Their nonlinear optical effects and other characteristics also make them suitable for integration into waveguide components, such as optical fibers, for applications like optical modulation. Although some efforts have been made to integrate perovskite nanomaterials with optical fibers, technological challenges have hindered reliable in-situ preparation methods. Herein, we propose an area-selective wetting strategy for optical fibers, which utilizes hydrophobic sidewalls and hydrophilic end facets to reliably hold small precursor droplets. By introducing a space confinement strategy to suppress the kinetics of solvent evaporation, Methylammonium lead bromide (MAPbBr3) perovskite single crystals were successfully grown in-situ on the fiber end facet. The versatility of this in-situ growth method for single crystals on fiber end facets of various sizes has also been verified. In a separate approach, the controllable in-situ preparation of CsPbBr3 polycrystalline thin films was achieved through vacuum-assisted rapid crystallization. Our strategy provides a controllable platform for the integration of perovskite materials and optical fibers, enabling further development in optical applications. △ Less

Submitted 17 November, 2025; originally announced November 2025.

Probing the atomic dynamics of ultrafast melting with femtosecond electron diffraction

Authors: M. Z. Mo, M. B. Maigler, T. Held, B. K. Ofori-Okai, A. Bergermann, Z. Chen, R. K. Li, X. Shen, K. Sokolowski-Tinten, R. Redmer, X. J. Wang, J. Schein, D. O. Gericke, B. Rethfeld, S. H. Glenzer

Abstract: Melting is an everyday phase transition that is determined by thermodynamic parameters like temperature and pressure. In contrast, ultrafast melting is governed by the microscopic response to a rapid energy input and, thus, can reveal the strength and dynamics of atomic bonds as well as the energy flow rate to the lattice. Accurately describing these processes remains challenging and requires deta… ▽ More Melting is an everyday phase transition that is determined by thermodynamic parameters like temperature and pressure. In contrast, ultrafast melting is governed by the microscopic response to a rapid energy input and, thus, can reveal the strength and dynamics of atomic bonds as well as the energy flow rate to the lattice. Accurately describing these processes remains challenging and requires detailed insights into transient states encountered. Here, we present data from femtosecond electron diffraction measurements that capture the structural evolution of copper during the ultrafast solid to liquid phase transformations. At absorbed energy densities 2 to 4 times the melting threshold, melting begins at the surface slightly below the nominal melting point followed by rapid homogeneous melting throughout the volume. Molecular dynamics simulations reproduce these observations and reveal a weak electron lattice energy transfer rate for the given experimental conditions. Both simulations and experiments show no indications of rapid lattice collapse when its temperature surpasses proposed limits of superheating, providing evidence that inherent dynamics limits the speed of disordering in ultrafast melting of metals. △ Less

Submitted 7 November, 2025; originally announced November 2025.

Comments: 36 pages, 5 figures, 2 extended data figures

Universal Decay of Mutual Information and Conditional Mutual Information in Gapped Pure- and Mixed-State Quantum Matter

Authors: Jinmin Yi, Kangle Li, Chuan Liu, Zixuan Li, Liujun Zou

Abstract: For spin and fermionic systems in any spatial dimension, we establish that the superpolynomial decay behavior of mutual information and conditional mutual information is a universal property of gapped pure- and mixed-state phases; i.e., all systems in such a phase possess this property if one system in this phase possesses this property. We further demonstrate that the (conditional) mutual informa… ▽ More For spin and fermionic systems in any spatial dimension, we establish that the superpolynomial decay behavior of mutual information and conditional mutual information is a universal property of gapped pure- and mixed-state phases; i.e., all systems in such a phase possess this property if one system in this phase possesses this property. We further demonstrate that the (conditional) mutual information indeed decays superpolynomially in a large class of phases, including chiral phases. As a by-product, we sharpen the notion of mixed-state phases. △ Less

Submitted 19 March, 2026; v1 submitted 26 October, 2025; originally announced October 2025.

Comments: 8+17 pages, 3+3 figures

Journal ref: Phys. Rev. Lett. 136, 116604 (2026)

Two-Dimensional Altermagnetism in Epitaxial CrSb Ultrathin Films

Authors: Keren Li, Yuzhong Hu, Yue Li, Ruohang Xu, Heping Li, Kun Liu, Chen Liu, Jincheng Zhuang, Yee Sin Ang, Jiaou Wang, Haifeng Feng, Weichang Hao, Yi Du

Abstract: Altermagnets constitute an emerging class of collinear magnets that exhibit zero net magnetization yet host spin-split electronic bands arising from non-relativistic spin-space-group symmetries. Realization of altermagnetism in the two-dimensional (2D) limit remains an outstanding challenge because dimensional reduction suppresses kZ dispersion and destabilizes the symmetry operations essential fo… ▽ More Altermagnets constitute an emerging class of collinear magnets that exhibit zero net magnetization yet host spin-split electronic bands arising from non-relativistic spin-space-group symmetries. Realization of altermagnetism in the two-dimensional (2D) limit remains an outstanding challenge because dimensional reduction suppresses kZ dispersion and destabilizes the symmetry operations essential for spin compensation. Here, we demonstrate genuine 2D altermagnetism in epitaxial unit-cell-thin films of CrSb grown on Bi2Te3. It reveals a thickness-driven transition from a ferrimagnetic state in 1-unit-cell films to an altermagnetic state above a critical thickness of 7/4 unit cell. The transition originates from interfacial symmetry breaking at the Cr-terminated layer that induces local moment imbalance. With increasing thickness the key spin-space-group symmetries [C2||C6Zt] and [C2||MZ] restores, which leads to altermagnetism with zero net magnetization and momentum-dependent spin splitting. Our results provide the first experimental realization of altermagnetism in the 2D regime and establish a route for integrating stray-field-free spin order into nanoscale spintronic architectures. △ Less

Submitted 14 October, 2025; originally announced October 2025.

Anti-hyperuniform Critical States of Active Topological Defects

Authors: Simon Guldager Andersen, Tianxiang Ma, Makito F. Katsume, Kexin Li, Xiao Liu, Martin Cramer Pedersen, Amin Doostmohammadi

Abstract: Topological defects are fundamental to the collective dynamics of non-equilibrium systems and in active matter, mediating spontaneous flows, dynamic self-organization, and emergent pattern formation. Here, we reveal critical states in active nematics, marked by slowed defect density relaxation, amplified fluctuations, and heightened sensitivity to activity. Near criticality, defect interactions be… ▽ More Topological defects are fundamental to the collective dynamics of non-equilibrium systems and in active matter, mediating spontaneous flows, dynamic self-organization, and emergent pattern formation. Here, we reveal critical states in active nematics, marked by slowed defect density relaxation, amplified fluctuations, and heightened sensitivity to activity. Near criticality, defect interactions become long-ranged, scaling with system size, and the system enters an anti-hyperuniform regime with giant number fluctuations of topological defects and defect clustering. This transition reflects a dual scaling behavior: fluctuations are uniform at small scales but become anti-hyperuniform at larger scales, \tm{as supported by experimental measurements on large-field-of-view endothelial monolayers. We find that these anti-hyperuniform states with multiscale defect density fluctuations are robust to varying parameters, introducing frictional damping, and changing boundary conditions.} Finally, we show that the observed anti-hyperuniformity originates from defect clustering, distinguishing this transition from defect-unbinding or phase separation processes. Beyond fundamental implications for non-equilibrium systems, these results may inform biological contexts where topological defects are integral to processes such as morphogenesis and collective cellular self-organization. △ Less

Submitted 26 September, 2025; originally announced September 2025.

Comments: This is the Accepted Manuscript version of an article accepted for publication in Reports on Progress in Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it

Mott Glass and Criticality in a S=1/2 Bilayer Heisenberg Model with Interlayer Bond Dilution

Authors: Kunpeng Li, Han-Qing Wu, Dao-Xin Yao

Abstract: We employ the stochastic series expansion quantum Monte Carlo (SSE-QMC) method to investigate the $S = 1/2$ antiferromagnetic Heisenberg model on a bilayer square lattice with diluted interlayer couplings. Both regular and random dilution patterns are considered. In systems with regular dilution, tuning the interlayer interaction drives a quantum phase transition from a Néel-ordered phase to a qua… ▽ More We employ the stochastic series expansion quantum Monte Carlo (SSE-QMC) method to investigate the $S = 1/2$ antiferromagnetic Heisenberg model on a bilayer square lattice with diluted interlayer couplings. Both regular and random dilution patterns are considered. In systems with regular dilution, tuning the interlayer interaction drives a quantum phase transition from a Néel-ordered phase to a quantum disordered phase, consistent with the $O(3)$ universality class. In contrast, random dilution gives rise to a two-step transition: from the Néel phase to an intermediate Mott glass (MG) phase, followed by a transition to the quantum disordered phase. Within the MG phase, the uniform magnetic susceptibility exhibits a stretched-exponential temperature dependence $χ_u \sim \exp(-b/T^α)$, $0 < α< 1$. At the Néel-to-glass transition, quenched disorder modifies the critical exponents in a manner consistent with the Harris criterion. These findings provide new insights into disorder-driven quantum phase transitions and the emergence of glassy phases in diluted bilayer quantum magnets. △ Less

Submitted 3 September, 2025; originally announced September 2025.

Isotopically Selected Single Antimony Molecule Doping

Authors: Mason Adshead, Maddison Coke, Evan Tillotson, Kexue Li, Sam Sullivan-Allsop, Ricardo Egoavil, William Thornley, Yi Cui, Christopher M Gourlay, Katie L Moore, Sarah J Haigh, Richard J Curry

Abstract: A reliable route to the deterministic fabrication of impurity ion donors in silicon is required to advance quantum computing architectures based upon such systems. This paper reports the ability to dope isotopically-defined unique (${}^{121}\mathrm{Sb}{}^{123}\mathrm{Sb}$) clusters into silicon with measured detection efficiencies of 94% being obtained. Atomically resolved imaging of the doped clu… ▽ More A reliable route to the deterministic fabrication of impurity ion donors in silicon is required to advance quantum computing architectures based upon such systems. This paper reports the ability to dope isotopically-defined unique (${}^{121}\mathrm{Sb}{}^{123}\mathrm{Sb}$) clusters into silicon with measured detection efficiencies of 94% being obtained. Atomically resolved imaging of the doped clusters reveals a Sb-to-Sb separation of ~2 nm post-implantation, thus indicating suitability to form coupled qudit systems. The method used is fully compatible with integration into processing that includes pre-enrichment of the silicon host to < 3ppm ${}^{29}\mathrm{Si}$ levels. As such, we present a potential pathway to the creation of scaled qudit arrays within silicon platforms for quantum computing. △ Less

Submitted 3 September, 2025; originally announced September 2025.

Comments: 10 pages, 4 figures

Experimental realization of dice-lattice flat band at the Fermi level in layered electride YCl

Authors: Songyuan Geng, Xin Wang, Risi Guo, Chen Qiu, Fangjie Chen, Qun Wang, Kangjie Li, Peipei Hao, Hanpu Liang, Yang Huang, Yunbo Wu, Shengtao Cui, Zhe Sun, Timur K. Kim, Cephise Cacho, Daniel S. Dessau, Benjamin T. Zhou, Haoxiang Li

Abstract: Flat electronic bands, where interactions among electrons overwhelm their kinetic energies, hold the promise for exotic correlation physics. The dice lattice has long been theorized as a host of flat bands with intriguing band topology. However, to date, no material has ever been found to host the characteristic flat bands of a dice lattice. Here, using angle-resolved photoemission spectroscopy (A… ▽ More Flat electronic bands, where interactions among electrons overwhelm their kinetic energies, hold the promise for exotic correlation physics. The dice lattice has long been theorized as a host of flat bands with intriguing band topology. However, to date, no material has ever been found to host the characteristic flat bands of a dice lattice. Here, using angle-resolved photoemission spectroscopy (ARPES), we discover a dice-lattice flat band at $E_F$ in the van der Waals (vdW) electride [YCl]$^{2+}$: 2e-. In this system, excess valence electrons from Y deconfine from the cation framework to form an interstitial anionic electron lattice that constitutes the dice lattice. Our ARPES measurements unambiguously identify two sets of dice-lattice bands in YCl, including a nearly dispersionless band at the Fermi level. The flat bands and other dispersive bands observed in ARPES find excellent agreement with first-principles calculations, and theoretical analysis reveals that the near-$E_F$ electronic structure is well captured by a simple dice-lattice model. Our findings thus end the long quest of a real dice flat band material and establish vdW electride YCl as a prototype of dice metals. Our results further demonstrate the anionic electron lattice as a novel scheme for realizing lattice geometries and electronic structures rare to find in conventional crystalline systems. △ Less

Submitted 28 August, 2025; originally announced August 2025.

Journal ref: Nat Commun 17, 2213 (2026)

New Upper Bounds on Exotic Neutron Spin-Electron Spin Interactions via Neutron Spin Rotation Measurements in a Compensated Ferrimagnet

Authors: T. Mulkey, K. N. Lopez, C. D. Hughes, B. Hill, M. Van Meter, H. Wijeratne, J. C. Long, M. Sarsour, W. M. Snow, K. Li, R. Parajuli, S. Samiei, D. V. Baxter, M. Luxnat, Y. Zhang, C. Jiang, E. Stringfellow, J. Torres, R. Hobbs

Abstract: We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the Standard Model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization… ▽ More We report a search for exotic spin-spin interactions between neutrons and electrons which could signal new physics beyond the Standard Model using slow neutron polarimetric imaging through a dense medium of polarized electrons. Our dense polarized electron target is a ferrimagnet held at its magnetic compensation temperature, which realizes a polarized electron ensemble with zero net magnetization. We sought the spin rotation of transversely polarized neutrons from a neutron spin-electron spin interaction of the form $V_2=-g_A^eg_A^n\frac{\hbar c}{4π}\vecσ_e\cdot\vecσ_n\frac{e^{-r/λ_c}}{r}$, where $g_{A}^{e}$ and $g_{A}^{n}$ are the electron and neutron axial couplings, $\vec{σ_e}$ and $\vec{σ_n}$ are the electron and neutron spin, and $λ_c$ is the interaction range for an exotic axial vector interaction from massive spin-1 boson exchange of mass $\hbar c/λ_c$. The resulting average neutron spin rotation angle per unit length, $\frac{d\barφ_{F5}}{dz}=[0.41\pm6.30\ (stat.)\pm4.4\ (sys.)]\times10^{-3}$ rad/m, is consistent with zero. Our novel approach improves the previous upper limits on the coupling constant product $g_A^eg_A^n$ by several orders of magnitude in the poorly explored $10^{-8}\leqλ_c\leq10^{-2}$ range. △ Less

Submitted 19 August, 2025; originally announced August 2025.

Strongly correlated electronic superconductivity in the noncentrosymmetric Re-Os-based high/medium-entropy alloys

Authors: Rui Chen, Longfu Li, Lingyong Zeng, Kuan Li, Peifeng Yu, Kangwang Wang, Zaichen Xiang, Shuangyue Wang, Jingjun Qin, Wanyi Zhang, Yucheng Li, Tian Shang, Huixia Luo

Abstract: The class of unconventional superconductors, particularly noncentrosymmetric superconductors, has been highly considered as potential materials for understanding the complex properties of quantum materials. Here, five previously unreported Re3.5Os3.5Ta0.5Hf0.5Nb3, Re3Os3Ta0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5W0.5Nb3, and Re3Os3Mo0.5Hf0.5Nb3 Re-Os-based high/medium-entropy alloys (M… ▽ More The class of unconventional superconductors, particularly noncentrosymmetric superconductors, has been highly considered as potential materials for understanding the complex properties of quantum materials. Here, five previously unreported Re3.5Os3.5Ta0.5Hf0.5Nb3, Re3Os3Ta0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5Hf0.5Nb3, Re3.5Os3.5Mo0.5W0.5Nb3, and Re3Os3Mo0.5Hf0.5Nb3 Re-Os-based high/medium-entropy alloys (MEAs-HEAs) with valence electron count ranging from 6.45 to 6.81 were synthesized and investigated using x-ray diffraction, transport, magnetization, and specific heat measurements. Our analyses confirm that all five compounds crystallize in a noncentrosymmetric α-Mn-type structure and exhibit type-II superconductivity with Tc values from 4.20 K to 5.11 K, respectively. Unexpectedly, despite being immersed in an acidic environment for one month, the structures and superconducting properties of HEAs remain stable. Our findings indicate that the Tc increases with an increasing valence electron count in MEAs-HEAs. Furthermore, these noncentrosymmetric α-Mn-type HEA superconductors have large Kadowaki-Woods ratios (KWR), implying the presence of strong electronic correlations. △ Less

Submitted 6 August, 2025; originally announced August 2025.

Comments: 27 pages, 7 figures, 1 table; The manuscript with the same title will be published by Acta Materialia

Journal ref: Acta Materialia 2025

Distinct Lifetimes for $X$ and $Z$ Loop Measurements in a Majorana Tetron Device

Authors: Morteza Aghaee, Zulfi Alam, Rikke Andersen, Mariusz Andrzejczuk, Andrey Antipov, Mikhail Astafev, Lukas Avilovas, Ahmad Azizimanesh, Eric Banek, Bela Bauer, Jonathan Becker, Umesh Kumar Bhaskar, Andrea G. Boa, Srini Boddapati, Nichlaus Bohac, Jouri D. S. Bommer, Jan Borovsky, Léo Bourdet, Samuel Boutin, Lucas Casparis, Srivatsa Chakravarthi, Hamidreza Chalabi, Benjamin J. Chapman, Nikolaos Chatzaras, Tzu-Chiao Chien , et al. (142 additional authors not shown)

Abstract: We present a hardware realization and measurements of a tetron qubit device in a superconductor-semiconductor heterostructure. The device architecture contains two parallel superconducting nanowires, which support four Majorana zero modes (MZMs) when tuned into the topological phase, and a trivial superconducting backbone. Two distinct readout interferometers are formed by connecting the supercond… ▽ More We present a hardware realization and measurements of a tetron qubit device in a superconductor-semiconductor heterostructure. The device architecture contains two parallel superconducting nanowires, which support four Majorana zero modes (MZMs) when tuned into the topological phase, and a trivial superconducting backbone. Two distinct readout interferometers are formed by connecting the superconducting structure to a series of quantum dots. We perform single-shot interferometric measurements of the fermion parity for the two loops, designed to implement Pauli-$X$ and $Z$ measurements of the tetron. Performing repeated single-shot measurements yields two widely separated time scales $τ_X = 14.5\pm 0.3 \, \mathrm{μs}$ and $τ_Z = 12.4\pm 0.4\, \mathrm{ms}$ for parity switches observed in the $X$ and $Z$ measurement loops, which we attribute to intra-wire parity switches and external quasiparticle poisoning, respectively. We estimate assignment errors of $\mathrm{err}^X_a=16\%$ and $\mathrm{err}^Z_a=0.5\%$ for $X$ and $Z$ measurement-based operations, respectively. △ Less

Submitted 4 September, 2025; v1 submitted 11 July, 2025; originally announced July 2025.

Comments: Extended discussion of switching dynamics and multiple time scales in App. A. Added App. C on alternative scenarios. Corrected Figs. 2(i) & A4. Explained the method for extracting multiple time scales from long time traces in App. A

Efficient GPU-Accelerated Training of a Neuroevolution Potential with Analytical Gradients

Authors: Hongfu Huang, Junhao Peng, Kaiqi Li, Jian Zhou, Zhimei Sun

Abstract: Machine-learning interatomic potentials (MLIPs) such as neuroevolution potentials (NEP) combine quantum-mechanical accuracy with computational efficiency significantly accelerate atomistic dynamic simulations. Trained by derivative-free optimization, the normal NEP achieves good accuracy, but suffers from inefficiency due to the high-dimensional parameter search. To overcome this problem, we prese… ▽ More Machine-learning interatomic potentials (MLIPs) such as neuroevolution potentials (NEP) combine quantum-mechanical accuracy with computational efficiency significantly accelerate atomistic dynamic simulations. Trained by derivative-free optimization, the normal NEP achieves good accuracy, but suffers from inefficiency due to the high-dimensional parameter search. To overcome this problem, we present a gradient-optimized NEP (GNEP) training framework employing explicit analytical gradients and the Adam optimizer. This approach greatly improves training efficiency and convergence speedily while maintaining accuracy and physical interpretability. By applying GNEP to the training of Sb-Te material systems(datasets include crystalline, liquid, and disordered phases), the fitting time has been substantially reduced-often by orders of magnitude-compared to the NEP training framework. The fitted potentials are validated by DFT reference calculations, demonstrating satisfactory agreement in equation of state and radial distribution functions. These results confirm that GNEP retains high predictive accuracy and transferability while considerably improved computational efficiency, making it well-suited for large-scale molecular dynamics simulations. △ Less

Submitted 1 July, 2025; originally announced July 2025.

Report number: Volume 320, March 2026, 109994

Journal ref: Computer Physics Communications, 2025: 109994

Probing d-wave superconducting gap of high-$T_\mathrm{c}$ cuprate $\mathrm{Bi}_2\mathrm{Sr}_2\mathrm{Ca}_2\mathrm{Cu}_3\mathrm{O}_{10+δ}$ by resonant inelastic X-ray scattering

Authors: Kunhao Li, Qizhi Li, Changwei Zou, Jaewon Choi, Chaohui Yin, Mirian Garcia-Fernandez, Stefano Agrestini, Shilong Zhang, Chengtian Lin, Xingjiang Zhou, Ke-Jin Zhou, Yi Lu, Yingying Peng

Abstract: The superconducting gap is a characteristic feature of high-T$_c$ superconductors and provides crucial information on the pairing mechanism underlying high-temperature superconductivity. Here, we employ high-resolution resonant inelastic X-ray scattering (RIXS) at the Cu $L_3$-edge to investigate the superconducting gap in the overdoped cuprate… ▽ More The superconducting gap is a characteristic feature of high-T$_c$ superconductors and provides crucial information on the pairing mechanism underlying high-temperature superconductivity. Here, we employ high-resolution resonant inelastic X-ray scattering (RIXS) at the Cu $L_3$-edge to investigate the superconducting gap in the overdoped cuprate $\mathrm{Bi}_2\mathrm{Sr}_2\mathrm{Ca}_2\mathrm{Cu}_3\mathrm{O}_{10+δ}$ ($T_\mathrm{c}$ = 107 K). By analyzing antisymmetrized, temperature-dependent RIXS spectra over a range of in-plane momentum transfers, we observe a clear suppression of low-energy spectral weight below T$_c$, indicative of superconducting gap formation. This suppression is most pronounced at small momentum transfers ($|\boldsymbol{q}_\parallel| \leq 0.18$ r.l.u.) and corresponds to a gap size of approximately 2$Δ_0 \sim$ 130 meV. Comparison with theoretical calculations of the momentum-dependent charge susceptibility supports a d-wave symmetry of the superconducting gap, while an isotropic s-wave gap fails to reproduce key experimental features. These findings establish RIXS as a powerful, bulk-sensitive probe of superconducting gap symmetry and highlight its utility for studying materials beyond the reach of surface-sensitive techniques such as ARPES and STM. △ Less

Submitted 23 June, 2025; originally announced June 2025.

Comments: 11 pages, 10 figures

Observation of average topological phase in disordered Rydberg atom array

Authors: Zongpei Yue, Yu-Feng Mao, Xinhui Liang, Zhen-Xing Hua, Peiyun Ge, Yu-Xin Chao, Kai Li, Chen Jia, Meng Khoon Tey, Yong Xu, Li You

Abstract: Topological phases have been extensively studied over the past two decades, primarily in quantum pure states, where they are protected by exact symmetries. Recently, numerous studies have theoretically demonstrated the existence of average symmetry-protected topological (SPT) phases in mixed quantum states, which naturally arise in real systems due to decoherence or disorder. Despite extensive exp… ▽ More Topological phases have been extensively studied over the past two decades, primarily in quantum pure states, where they are protected by exact symmetries. Recently, numerous studies have theoretically demonstrated the existence of average symmetry-protected topological (SPT) phases in mixed quantum states, which naturally arise in real systems due to decoherence or disorder. Despite extensive experimental observations of exact SPT phases in various systems, ranging from solid-state materials to synthetic matters, average SPT phases are yet to be observed until this work. Here we report direct observations of disorder-induced many-body interacting average SPT phase in an atom array at half-filling, whereby random offsets to tweezer locations forming a lattice implement structural disorder, resulting in fluctuating long-range dipolar interactions between tweezer confined single atoms. The induced topological phase is vindicated by the spatially resolved atom-atom correlation functions for different forms of dimer compositions. The ground state degeneracy in disordered configurations is detected and compared to the regular lattice without disorder. By probing the quench dynamics of a highly excited state, we observe markedly slower decay of edge spin magnetization in comparison to the bulk spin, consistent with the presence of topologically protected edge modes in disordered lattices. △ Less

Submitted 10 September, 2025; v1 submitted 7 May, 2025; originally announced May 2025.

Response to recent comments on Phys. Rev. B 107, 245423 (2023) and Subsection S4.3 of the Supp. Info. for Nature 638, 651-655 (2025)

Authors: Morteza Aghaee, Zulfi Alam, Mariusz Andrzejczuk, Andrey E. Antipov, Mikhail Astafev, Amin Barzegar, Bela Bauer, Jonathan Becker, Umesh Kumar Bhaskar, Alex Bocharov, Srini Boddapati, David Bohn, Jouri Bommer, Leo Bourdet, Samuel Boutin, Benjamin J. Chapman, Sohail Chatoor, Anna Wulff Christensen, Patrick Codd, William S. Cole, Paul Cooper, Fabiano Corsetti, Ajuan Cui, Andreas Ekefjärd, Saeed Fallahi , et al. (105 additional authors not shown)

Abstract: The topological gap protocol (TGP) is a statistical test designed to identify a topological phase with high confidence and without human bias. It is used to determine a promising parameter regime for operating topological qubits. The protocol's key metric is the probability of incorrectly identifying a trivial region as topological, referred to as the false discovery rate (FDR). Two recent manuscr… ▽ More The topological gap protocol (TGP) is a statistical test designed to identify a topological phase with high confidence and without human bias. It is used to determine a promising parameter regime for operating topological qubits. The protocol's key metric is the probability of incorrectly identifying a trivial region as topological, referred to as the false discovery rate (FDR). Two recent manuscripts [arXiv:2502.19560, arXiv:2503.08944] engage with the topological gap protocol and its use in Phys. Rev. B 107, 245423 (2023) and Subsection S4.3 of the Supplementary Information for Nature 638, 651-655 (2025), although they do not explicitly dispute the main results of either one. We demonstrate that the objections in arXiv:2502.19560 and arXiv:2503.08944 are unfounded, and we uphold the conclusions of Phys. Rev. B 107, 245423 (2023) and Nature 638, 651-655 (2025). Specifically, we show that no flaws have been identified in our estimate of the false discovery rate (FDR). We provide a point-by-point rebuttal of the comments in arXiv:2502.19560 and arXiv:2503.08944. △ Less

Submitted 17 April, 2025; originally announced April 2025.

Comments: Response to arXiv:2502.19560 and arXiv:2503.08944. 11 pages, 5 figures, 2 tables, code for reproduction

Superconductivity in the Medium-Entropy/High-Entropy Re-based Alloys with a Non-Centrosymmetric $α$-Mn Lattice

Authors: Kuan Li, Longfu Li, Lingyong Zenga, Yucheng Li, Rui Chen, Peifeng Yu, Kangwang Wang, Zaichen Xiang, Tian Shang, Huixia Luo

Abstract: Medium or high-entropy alloys (MEAs-HEAs) and rhenium-based compounds with a non-centrosymmetric (NC) structure have received a lot of attention for offering a fertile soil in search for unconventional superconductivity. Here, five previously unreported NC Re-based MEA-HEA superconductors with an $α$-Mn lattice are successfully synthesized, with their superconducting transition temperatures (Tcs)… ▽ More Medium or high-entropy alloys (MEAs-HEAs) and rhenium-based compounds with a non-centrosymmetric (NC) structure have received a lot of attention for offering a fertile soil in search for unconventional superconductivity. Here, five previously unreported NC Re-based MEA-HEA superconductors with an $α$-Mn lattice are successfully synthesized, with their superconducting transition temperatures (Tcs) ranging from 4 to 5 K. An increase in the superconducting transition temperature (Tc) can be achieved by modulating the valence electron count (VEC) through compositional adjustments. Magnetization measurements confirm that all the synthesized Re-based MEA-HEAs are bulk type-II superconductors. Specific heat analysis reveals that the superconducting state of these HEAs can be well described by a single-gap s-wave model. Our results show that the Kadowaki-Woods ratio of these $α$-Mn MEA/HEA superconductors are close to the typical value of heavy fermion compounds, suggesting the existence of strong electronic correlation. These findings provide promising material platforms to study the role of high disorder in the origin of superconductivity in the NC MEAs-HEAs. △ Less

Submitted 3 April, 2025; originally announced April 2025.

Comments: Superconductor Science and Technology, 2025

Probing Rate-Dependent Liquid Shear Viscosity Using Combined Machine Learning and Non-Equilibrium Molecular Dynamics

Authors: Hongyu Gao, Minghe Zhu, Jia Ma, Marc Honecker, Kexian Li

Abstract: Accurately measuring liquid dynamic viscosity across a wide range of shear rates, from the linear-response to shear-thinning regimes, presents significant experimental challenges due to limitations in resolving high shear rates and controlling thermal effects. In this study, we integrated machine learning (ML) with non-equilibrium molecular dynamics (NEMD) simulations to address these challenges.… ▽ More Accurately measuring liquid dynamic viscosity across a wide range of shear rates, from the linear-response to shear-thinning regimes, presents significant experimental challenges due to limitations in resolving high shear rates and controlling thermal effects. In this study, we integrated machine learning (ML) with non-equilibrium molecular dynamics (NEMD) simulations to address these challenges. A supervised artificial neural network (ANN) model was developed to predict viscosity as a function of shear rate, normal pressure, and temperature, effectively capturing the complex interplay among these variables. The model reveals distinct trends in shear viscosity, characterized by the shear-thinning exponent, and highlights non-monotonic behavior in the radius of gyration components, reflecting molecular morphological changes driven by rate-dependent volume expansion. Notably, temperature effects diminish at higher shear rates, where molecular alignment and spacing dominate the response to shear. By implementing the 'fix npt/sllod' command in LAMMPS, we achieve precise constant-pressure control in NEMD simulations, ensuring accurate representation of system dynamics. This study demonstrates the potential of ML-enhanced NEMD for efficient and accurate viscosity prediction, providing a robust framework for future research in complex fluid dynamics and material design. △ Less

Submitted 25 March, 2025; originally announced March 2025.

Light communicative materials

Authors: Hongshuang Guo, Kai Li, Jianfeng Yang, Dengfeng Li, Fan Liu, Hao Zeng

Abstract: The natural interactive materials under far-from-equilibrium conditions have significantly inspired advances in synthetic biomimetic materials. In artificial systems, gradient diffusion serves as the primary means of interaction between individuals, lacking directionality, sufficient interaction ranges and transmission rates. Here, we present a method for constructing highly directed, communicativ… ▽ More The natural interactive materials under far-from-equilibrium conditions have significantly inspired advances in synthetic biomimetic materials. In artificial systems, gradient diffusion serves as the primary means of interaction between individuals, lacking directionality, sufficient interaction ranges and transmission rates. Here, we present a method for constructing highly directed, communicative structures via optical feedback in light responsive materials. We showcase a photomechanical operator system comprising a baffle and a soft actuator. Positive and negative operators are configured to induce light-triggered deformations, alternately interrupting the passage of two light beams in a closed feedback loop. The fundamental functionalities of this optically interconnected material loop include homeostasis-like self-oscillation and signal transmission from one material to another via light. Refinements in alignment facilitate remote sensing, fiber-optic/long-distance communication, and adaptation. These proof-of-concept demonstrations outline a versatile design framework for light-mediated communication among responsive materials, with broad applicability across diverse materials. △ Less

Submitted 20 February, 2025; originally announced March 2025.

Thermodynamic speed limit for non-adiabatic work and its classical-quantum decomposition

Authors: Aoi Yamauchi, Rihito Nagase, Kaixin Li, Takahiro Sagawa, Ken Funo

Abstract: Understanding the fundamental constraint on work far beyond the adiabatic regime is crucial to investigating fast and efficient energy extraction or consumption processes. In this study, we derive thermodynamic speed limits for non-adiabatic work and quantify the fundamental costs of non-adiabatic work extraction or consumption processes in open quantum systems, where the costs are quantified by g… ▽ More Understanding the fundamental constraint on work far beyond the adiabatic regime is crucial to investigating fast and efficient energy extraction or consumption processes. In this study, we derive thermodynamic speed limits for non-adiabatic work and quantify the fundamental costs of non-adiabatic work extraction or consumption processes in open quantum systems, where the costs are quantified by geometric and thermodynamic quantities. We further decompose the non-adiabatic work into classical and quantum contributions and derive their thermodynamic speed limits, clarifying the classical and quantum nature of the fundamental costs. The obtained results are numerically demonstrated by driven two-level systems. △ Less

Submitted 28 April, 2025; v1 submitted 26 February, 2025; originally announced February 2025.

Comments: 17 pages, 1 figure

Journal ref: J. Phys. A: Math. Theor. 58 205001 (2025)

Quantum Emitters in Rhombohedral Boron Nitride

Authors: Angus Gale, Mehran Kianinia, Jake Horder, Connor Tweedie, Mridul Singhal, Dominic Scognamiglio, Jiajie Qi, Kaihui Li, Carla Verdi, Igor Aharonovich, Milos Toth

Abstract: Rhombohedral boron nitride (rBN) is an emerging wide-bandgap van der Waals (vdW) material that combines strong second-order nonlinear optical properties with the structural flexibility of layered 2D systems. Here we show that rBN hosts optically-addressable spin defects and single-photon emitters (SPEs). Both are fabricated deterministically, using site-specific techniques, and are compared to the… ▽ More Rhombohedral boron nitride (rBN) is an emerging wide-bandgap van der Waals (vdW) material that combines strong second-order nonlinear optical properties with the structural flexibility of layered 2D systems. Here we show that rBN hosts optically-addressable spin defects and single-photon emitters (SPEs). Both are fabricated deterministically, using site-specific techniques, and are compared to their analogues in hexagonal boron nitride (hBN). Emission spectra in hBN and rBN are compared, and computational models of defects in hBN and rBN are used to elucidate the debated atomic structure of the B-center SPE in BN. Our results establish rBN as a monolithic vdW platform that uniquely combines second-order nonlinear optical properties, optically addressable spin defects, and high-quality SPEs, opening new possibilities for integrated quantum and nonlinear photonics. △ Less

Submitted 20 February, 2025; originally announced February 2025.

Roadmap to fault tolerant quantum computation using topological qubit arrays

Authors: David Aasen, Morteza Aghaee, Zulfi Alam, Mariusz Andrzejczuk, Andrey Antipov, Mikhail Astafev, Lukas Avilovas, Amin Barzegar, Bela Bauer, Jonathan Becker, Juan M. Bello-Rivas, Umesh Bhaskar, Alex Bocharov, Srini Boddapati, David Bohn, Jouri Bommer, Parsa Bonderson, Jan Borovsky, Leo Bourdet, Samuel Boutin, Tom Brown, Gary Campbell, Lucas Casparis, Srivatsa Chakravarthi, Rui Chao , et al. (157 additional authors not shown)

Abstract: We describe a concrete device roadmap towards a fault-tolerant quantum computing architecture based on noise-resilient, topologically protected Majorana-based qubits. Our roadmap encompasses four generations of devices: a single-qubit device that enables a measurement-based qubit benchmarking protocol; a two-qubit device that uses measurement-based braiding to perform single-qubit Clifford operati… ▽ More We describe a concrete device roadmap towards a fault-tolerant quantum computing architecture based on noise-resilient, topologically protected Majorana-based qubits. Our roadmap encompasses four generations of devices: a single-qubit device that enables a measurement-based qubit benchmarking protocol; a two-qubit device that uses measurement-based braiding to perform single-qubit Clifford operations; an eight-qubit device that can be used to show an improvement of a two-qubit operation when performed on logical qubits rather than directly on physical qubits; and a topological qubit array supporting lattice surgery demonstrations on two logical qubits. Devices that enable this path require a superconductor-semiconductor heterostructure that supports a topological phase, quantum dots and coupling between those quantum dots that can create the appropriate loops for interferometric measurements, and a microwave readout system that can perform fast, low-error single-shot measurements. We describe the key design components of these qubit devices, along with the associated protocols for demonstrations of single-qubit benchmarking, Clifford gate execution, quantum error detection, and quantum error correction, which differ greatly from those in more conventional qubits. Finally, we comment on implications and advantages of this architecture for utility-scale quantum computation. △ Less

Submitted 18 July, 2025; v1 submitted 17 February, 2025; originally announced February 2025.

Comments: v2: 12+8 pages, 9+5 figures, significant main text and appendix revisions

Deep Spin Defects in Zinc Oxide for High-Fidelity Single-Shot Readout

Authors: Shimin Zhang, Taejoon Park, Erik Perez, Kejun Li, Xingyi Wang, Masoud Mansouri, Yanyong Wang, Jorge D Vega Bazantes, Ruiqi Zhang, Jianwei Sun, Kai-Mei C. Fu, Hosung Seo, Yuan Ping

Abstract: Wide-band gap oxides such as ZnO offer a favorable environment for spin defect qubits due to their dilute nuclear spin background and potential for ultra-high purity. Identifying deep-level defect qubits is essential for room-temperature optical initialization and quantum emission, robust against environmental noise. In this work, we theoretically design deep-level point defects in ZnO with optima… ▽ More Wide-band gap oxides such as ZnO offer a favorable environment for spin defect qubits due to their dilute nuclear spin background and potential for ultra-high purity. Identifying deep-level defect qubits is essential for room-temperature optical initialization and quantum emission, robust against environmental noise. In this work, we theoretically design deep-level point defects in ZnO with optimal physical properties for optically-addressable spin qubits. By employing first-principles calculations, we predict that the molybdenum-vacancy complex has promising spin and optical properties, including a spin-triplet ground state, optically-allowable transition in the visible range with a high quantum yield, and an exceptionally small Huang-Rhys factor around 5, compared to 10-30 in known defects in ZnO. In particular, we found a long spin decoherence T2 time at 4 ms after considering both nuclear spin baths and paramagnetic impurity baths' interactions, with the latter dominant at impurity concentration above 0.035 ppm. Finally, we predict the energy diagram with spin-selective intersystem crossing for a spin-photon interface, and suggest the protocols for efficient optical readout. With a strong spin-orbit coupling and the absence of Jahn-Teller distortion in the proposed defect, we reveal that it supports high-fidelity single-shot readout of electron-spin at high temperature and a wide range of magnetic field. △ Less

Submitted 12 July, 2025; v1 submitted 1 February, 2025; originally announced February 2025.

Comments: 7 figures

Beyond the band edge: Unveiling high-mobility hot carriers in a two-dimensional conjugated coordination polymer

Authors: Shuai Fu, Xing Huang, Guoquan Gao, Petko St. Petkov, Wenpei Gao, Jianjun Zhang, Lei Gao, Heng Zhang, Min Liu, Mike Hambsch, Wenjie Zhang, Jiaxu Zhang, Keming Li, Ute Kaiser, Stuart S. P. Parkin, Stefan C. B. Mannsfeld, Tong Zhu, Hai I. Wang, Zhiyong Wang, Renhao Dong, Xinliang Feng, Mischa Bonn

Abstract: Hot carriers, inheriting excess kinetic energy from high-energy photons, underpin numerous optoelectronic applications involving non-equilibrium transport processes. Current research on hot carriers has predominantly focused on inorganic materials, with little attention paid to organic-based systems due to their ultrafast energy relaxation and inefficient charge transport. Here, we overturn this p… ▽ More Hot carriers, inheriting excess kinetic energy from high-energy photons, underpin numerous optoelectronic applications involving non-equilibrium transport processes. Current research on hot carriers has predominantly focused on inorganic materials, with little attention paid to organic-based systems due to their ultrafast energy relaxation and inefficient charge transport. Here, we overturn this paradigm by demonstrating highly mobile hot carriers in solution-processable, highly crystalline two-dimensional conjugated coordination polymer (2D c-CP) Cu3BHT (BHT = benzenehexathiol) films. Leveraging a suite of ultrafast spectroscopic and imaging techniques, we unravel the microscopic charge transport landscape in Cu3BHT films following non-equilibrium photoexcitation across temporal, spatial, and frequency domains, revealing two distinct high-mobility transport regimes. In the non-equilibrium transport regime, hot carriers achieve ultrahigh mobility of ~2,000 cm2 V-1 s-1, traversing grain boundaries up to 300 nm within a picosecond. In the quasi-equilibrium transport regime, free carriers exhibit Drude-type band-like transport with a remarkable mobility of ~400 cm2 V-1 s-1 and an intrinsic diffusion length exceeding 1 micrometer. These findings establish 2D c-CPs as versatile platforms for exploring high-mobility non-equilibrium transport, unlocking new opportunities for organic-based hot carrier applications. △ Less

Submitted 15 January, 2025; originally announced January 2025.

Comments: 27 pages, 4 figures

Large upper critical fields and strong coupling superconductivity in the medium-entropy alloy (Ti1/3Hf1/3Ta1/3)1-xNbx

Authors: Longfu Li, Hongyan Tian, Xunwu Hu, Lingyong Zeng, Kuan Li, Peifeng Yu, Kangwang Wang, Rui Chen, Zaichen Xiang, Dao-Xin Yao, Huixia Luo

Abstract: Since the discovery of high-entropy superconductors in 2014, superconductivity has remained a focal point of interest in medium- and high-entropy alloys (MEAs-HEAs). Here, we report a series of (Ti0.33Hf0.33Ta0.33)1-xNbx MEA superconductors crystallized in the BCC structure, whose superconductivity was characterized by resistivity, magnetization, and specific heat measurements. The study found tha… ▽ More Since the discovery of high-entropy superconductors in 2014, superconductivity has remained a focal point of interest in medium- and high-entropy alloys (MEAs-HEAs). Here, we report a series of (Ti0.33Hf0.33Ta0.33)1-xNbx MEA superconductors crystallized in the BCC structure, whose superconductivity was characterized by resistivity, magnetization, and specific heat measurements. The study found that the (Ti0.33Hf0.33Ta0.33)1-xNbx MEAs exhibit bulk superconductivity. With the doping of Nb, the superconducting transition temperature (Tc) increases from 5.31 K to 9.11 K, and the normalized Cel jumps at Tc, and the logarithmically averaged characteristic phonon frequency exhibit dome-shaped curves. Results from specific heat measurements indicate that the superconductivity is of a strongly coupled s-wave type observed. Furthermore, at low Nb content, the upper critical field of the samples is larger than the Pauli paramagnetic limit. The strongly coupling behavior and large upper critical field in s-wave type (Ti0.33Hf0.33Ta0.33)1-xNbx MEA superconductors are unusual, as they typically occur in other unconventional superconductors. Thus, (Ti0.33Hf0.33Ta0.33)1-xNbx may have significant potential in the research and understanding of physical mechanisms. △ Less

Submitted 5 January, 2025; originally announced January 2025.

Comments: 20 pages, 5 figures

Journal ref: Superconductor Science and Technology,2025

Disentangling Cation-Polyanion Coupling in Solid Electrolytes: Which Anion Motion Dominates Cation Transport?

Authors: Ke Li, Jitai Yang, Yu Zhai, Hui Li

Abstract: Lithium and sodium solid electrolytes feature polyanion frameworks and highly mobile cations. Understanding and quantifying the impact of polyanion dynamics on cations will help us to unravel the complex role that anion play in superionic conductors. However, no experimental or computational method can directly extract this information, as polyanion dynamics are always coupled with other factors t… ▽ More Lithium and sodium solid electrolytes feature polyanion frameworks and highly mobile cations. Understanding and quantifying the impact of polyanion dynamics on cations will help us to unravel the complex role that anion play in superionic conductors. However, no experimental or computational method can directly extract this information, as polyanion dynamics are always coupled with other factors that affect ion mobility. Here, we present the pioneering study that combines constraint algorithm and machine-learning molecular dynamics to quantitatively reveal the effects of polyanion translation, rotation, and vibration on cation mobility across a diverse material class. Ultralong-time, large-scale machine-learning molecular dynamics simulations with selective constraints on each anion motion mode unequivocally yield results at near room and elevated temperatures. In sharp contrast to the previous understanding that facile anion rotation primarily facilitates cation transport, the strong coupling between anion translation and vibration with cation diffusion has been unraveled for the first time; we find that translation, rotation, and vibration can each directly drive superionicity, with one typically dominant in each class of materials. Anion rotation dominates cation transport when the rotation frequency matches the cation hopping frequency, whereas anion translation prevails at higher and vibration at lower rotation frequencies. The impact of anion dynamics on cation diffusion becomes more prominent at lower temperatures. △ Less

Submitted 4 January, 2025; originally announced January 2025.

Symmetry-enforced minimal entanglement and correlation in quantum spin chains

Authors: Kangle Li, Liujun Zou

Abstract: The interplay between symmetry, entanglement and correlation is an interesting and important topic in quantum many-body physics. Within the framework of matrix product states, in this paper we study the minimal entanglement and correlation enforced by the $SO(3)$ spin rotation symmetry and lattice translation symmetry in a quantum spin-$J$ chain, with $J$ a positive integer. When neither symmetry… ▽ More The interplay between symmetry, entanglement and correlation is an interesting and important topic in quantum many-body physics. Within the framework of matrix product states, in this paper we study the minimal entanglement and correlation enforced by the $SO(3)$ spin rotation symmetry and lattice translation symmetry in a quantum spin-$J$ chain, with $J$ a positive integer. When neither symmetry is spontaneously broken, for a sufficiently long segment in a sufficiently large closed chain, we find that the minimal Rényi-$α$ entropy compatible with these symmetries is $\min\{ -\frac{2}{α-1}\ln(\frac{1}{2^α}({1+\frac{1}{(2J+1)^{α-1}}})), 2\ln(J+1) \}$, for any $α\in\mathbb{R}^+$. In an infinitely long open chain with such symmetries, for any $α\in\mathbb{R}^+$ the minimal Rényi-$α$ entropy of half of the system is $\min\{ -\frac{1}{α-1}\ln(\frac{1}{2^α}({1+\frac{1}{(2J+1)^{α-1}}})), \ln(J+1) \}$. When $α\rightarrow 1$, these lower bounds give the symmetry-enforced minimal von Neumann entropies in these setups. Moreover, we show that no state in a quantum spin-$J$ chain with these symmetries can have a vanishing correlation length. Interestingly, the states with the minimal entanglement may not be a state with the minimal correlation length. △ Less

Submitted 18 July, 2025; v1 submitted 30 December, 2024; originally announced December 2024.

Comments: 17 pages + appendices + references

Journal ref: SciPost Phys. 19, 020 (2025)

Superconductivity in the medium entropy alloys Nb2TiW and Nb2TiMo

Authors: Kuan Li, Cui Qun Chen, Lingyong Zeng, Longfu Li, Rui Chen, Peifeng Yu, Kangwang Wang, Zaichen Xiang, Dao Xin Yao, Huixia Luo

Abstract: This study describes the synthesis and characterization of Nb2TiW and Nb2TiMo medium entropy alloys (MEAs). The Nb2TiW and Nb2TiMo MEAs can be successfully synthesized by an arc melting method. Their structures and superconducting properties are investigated by detailed characterization of X ray diffraction (XRD), resistivity, magnetization, and specific heat measurements. XRD results confirm that… ▽ More This study describes the synthesis and characterization of Nb2TiW and Nb2TiMo medium entropy alloys (MEAs). The Nb2TiW and Nb2TiMo MEAs can be successfully synthesized by an arc melting method. Their structures and superconducting properties are investigated by detailed characterization of X ray diffraction (XRD), resistivity, magnetization, and specific heat measurements. XRD results confirm that the obtained Nb2TiW and Nb2TiMo compounds have the same body-centered cubic (BCC) structures. Experimental results show that the superconducting transition temperatures Tcs of Nb2TiW and Nb2TiMo are around 4.86 K and 3.22 K, respectively. The upper and lower critical fields of Nb2TiW are 3.52(2) T and 53.36(2) Oe, respectively, and those of Nb2TiMo are 2.11(2) T and 68.23(3) Oe, respectively. First-principles calculations reveal that the d electrons of Nb, Ti, and Mo or W are the dominant contribution of the density of states near the Fermi level. Specific heat measurement results indicate that Nb2TiW and Nb2TiMo display BCS full-gap s-wave superconductivity. △ Less

Submitted 11 December, 2024; originally announced December 2024.

Comments: 22 pages, 9 figures;The manuscript with the same title will be published by Chinese Physics Letters

Journal ref: Chinese Physics Letters,2024

Exotic properties and manipulation in 2D semimetal Mn2B2(OH)2: a theoretical study

Authors: Pingwei Liu, Dan Liu, Shixin Song, Kang Li, Xueyong Yuan, Jie Guan

Abstract: Most functional materials possess one single outstanding property and are limited to be used for a particular purpose. Instead of integrating materials with different functions into one module, designing materials with controllable multi-functions is more promising for the electronic industry. In this study, we investigate an unexplored alpha-phase of two-dimensional (2D) Mn2B2(OH)2 theoretically.… ▽ More Most functional materials possess one single outstanding property and are limited to be used for a particular purpose. Instead of integrating materials with different functions into one module, designing materials with controllable multi-functions is more promising for the electronic industry. In this study, we investigate an unexplored alpha-phase of two-dimensional (2D) Mn2B2(OH)2 theoretically. Eighteen distinct electrical polarizations, characterized by three different magnitudes and twelve different directions, are found in this phase. The switch of the electrical polarizations is also linked to an observed splitting of band structures between different spin states and the ferroelasticity of the system. The manipulation of these properties can be realized through controlling the alignment of Mn-OH-Mn chains. Additionally, the approximately honeycomb lattice for the atomic layer of boron indicate the potential superconductivity in the system. The diverse and tunable properties make the proposed material as an outstanding candidate for sensing applications at the 2D limit. △ Less

Submitted 6 December, 2024; originally announced December 2024.

Comments: Accepted by Physical Review B

Anomalous Hall effect from inter-superlattice scattering in a noncollinear antiferromagnet

Authors: Lilia S. Xie, Shannon S. Fender, Cameron Mollazadeh, Wuzhang Fang, Matthias D. Frontzek, Samra Husremović, Kejun Li, Isaac M. Craig, Berit H. Goodge, Matthew P. Erodici, Oscar Gonzalez, Jonathan P. Denlinger, Yuan Ping, D. Kwabena Bediako

Abstract: Superlattice formation dictates the physical properties of many materials, including the nature of the ground state in magnetic materials. Chemical composition is commonly considered to be the primary determinant of superlattice identity, especially in intercalation compounds. Here, we find that, contrary to this conventional wisdom, kinetic control of superlattice growth leads to the coexistence… ▽ More Superlattice formation dictates the physical properties of many materials, including the nature of the ground state in magnetic materials. Chemical composition is commonly considered to be the primary determinant of superlattice identity, especially in intercalation compounds. Here, we find that, contrary to this conventional wisdom, kinetic control of superlattice growth leads to the coexistence of disparate domains within a compositionally "perfect" single crystal. We demonstrate that Cr$_{1/4}$TaS$_2$ is a bulk noncollinear antiferromagnet in which scattering between bulk and minority superlattice domains engenders complex magnetotransport below the Néel temperature, including an anomalous Hall effect. We characterize the magnetic phases in different domains, image their nanoscale morphology, and propose a mechanism for nucleation and growth. These results provide a blueprint for the deliberate engineering of macroscopic transport responses via microscopic patterning of magnetic exchange interactions in superlattice domains. △ Less

Submitted 14 November, 2024; v1 submitted 13 November, 2024; originally announced November 2024.

Comments: 50 pages, 19 figures, 6 tables

Effects of Lanthanides on the Structure and Oxygen Permeability of Ti-doped Dual-phase Membranes

Authors: Chao Zhang, Zaichen Xiang, Lingyong Zeng, Peifeng Yu, Kuan Li, Kangwang Wang, Longfu Li, Rui Chen, Huixia Luo

Abstract: The trade-off effect of the oxygen permeability and stability of oxygen transport membranes (OTMs) still exists in working atmospheres containing CO2. Herein, we reported a new series of 60 wt%Ce0.9Ln0.1O2-δ-40wt%Ln0.6Sr0.4Fe0.9Ti0.1O3-δ (CLnO-LnSFTO, Ln = La, Pr, Nd, Sm, Gd, Tb) dual-phase OTMs by selecting different Ln elements based on the reported highly stable Ti-doped CPrO-PrSFTO. The effect… ▽ More The trade-off effect of the oxygen permeability and stability of oxygen transport membranes (OTMs) still exists in working atmospheres containing CO2. Herein, we reported a new series of 60 wt%Ce0.9Ln0.1O2-δ-40wt%Ln0.6Sr0.4Fe0.9Ti0.1O3-δ (CLnO-LnSFTO, Ln = La, Pr, Nd, Sm, Gd, Tb) dual-phase OTMs by selecting different Ln elements based on the reported highly stable Ti-doped CPrO-PrSFTO. The effects of different Ln elements on the structure and oxygen permeability of Ti-doped dual-phase OTMs were systematically studied. Basically, as the atomic number of Ln elements increases, the unit cell parameters of both the fluorite phase and the perovskite phase become smaller. The unit cell volume and spatial symmetry of the perovskite phase are reduced, resulting in a reduction in oxygen permeability. The optimal CLaO-LaSFTO showed JO2 of 0.60 and 0.54 mL min-1 cm-2 with He and CO2 sweeping at 1000 oC, respectively. In addition, all CLnO-LnSFTO OTMs could work for more than 100 hours with no significant performance degradation in a CO2 atmosphere, maintaining excellent stability. This work explores candidate OTM materials for CO2 capture and oxygen separation, as well as provides some ideas for addressing the trade-off effect. △ Less

Submitted 4 November, 2024; originally announced November 2024.

Comments: 28 pages, 7 figures

Journal ref: Journal of Membrane Science,2024

Density Functional Theory Study of Surface Stability and Phase Diagram of Orthorhombic CsPbI3

Authors: Kejia Li, Mengen Wang

Abstract: CsPbI3 has been recognized as a promising candidate for optoelectronic device applications. To further improve the efficiency of the devices, it is imperative to better understand the surface properties of CsPbI3, which affect charge carrier transport and defect formation properties. In this study, we perform density functional theory calculations to explore the stability of the (001), (110), and… ▽ More CsPbI3 has been recognized as a promising candidate for optoelectronic device applications. To further improve the efficiency of the devices, it is imperative to better understand the surface properties of CsPbI3, which affect charge carrier transport and defect formation properties. In this study, we perform density functional theory calculations to explore the stability of the (001), (110), and (100) surfaces of orthorhombic CsPbI3, considering different stoichiometries and surface reconstructions. Our results show that, under the chemical potentials confined by the thermodynamically stable region of bulk CsPbI3, the CsI-terminated surfaces of (001) and (110) and the stoichiometric surface of (100) are stable. Among these three surfaces, the CsI-terminated (110) surface has the lowest surface energy and no mid-gap states, which benefits the transport properties of the material. △ Less

Submitted 3 November, 2024; originally announced November 2024.

LLM4Mat-Bench: Benchmarking Large Language Models for Materials Property Prediction

Authors: Andre Niyongabo Rubungo, Kangming Li, Jason Hattrick-Simpers, Adji Bousso Dieng

Abstract: Large language models (LLMs) are increasingly being used in materials science. However, little attention has been given to benchmarking and standardized evaluation for LLM-based materials property prediction, which hinders progress. We present LLM4Mat-Bench, the largest benchmark to date for evaluating the performance of LLMs in predicting the properties of crystalline materials. LLM4Mat-Bench con… ▽ More Large language models (LLMs) are increasingly being used in materials science. However, little attention has been given to benchmarking and standardized evaluation for LLM-based materials property prediction, which hinders progress. We present LLM4Mat-Bench, the largest benchmark to date for evaluating the performance of LLMs in predicting the properties of crystalline materials. LLM4Mat-Bench contains about 1.9M crystal structures in total, collected from 10 publicly available materials data sources, and 45 distinct properties. LLM4Mat-Bench features different input modalities: crystal composition, CIF, and crystal text description, with 4.7M, 615.5M, and 3.1B tokens in total for each modality, respectively. We use LLM4Mat-Bench to fine-tune models with different sizes, including LLM-Prop and MatBERT, and provide zero-shot and few-shot prompts to evaluate the property prediction capabilities of LLM-chat-like models, including Llama, Gemma, and Mistral. The results highlight the challenges of general-purpose LLMs in materials science and the need for task-specific predictive models and task-specific instruction-tuned LLMs in materials property prediction. △ Less

Submitted 30 November, 2024; v1 submitted 31 October, 2024; originally announced November 2024.

Comments: Accepted at NeurIPS 2024-AI4Mat Workshop. The Benchmark and code can be found at https://github.com/vertaix/LLM4Mat-Bench

Designed self-assembly of programmable colloidal atom-electron equivalents

Authors: Xiuyang Xia, Yuhan Peng, Ka Ki Li, Ran Ni

Abstract: To unlock the potential for assembling complex colloidal "molecules", we investigate a minimal binary system of programmable colloidal atom-electron equivalents (PAE-EE), where electron equivalents (EEs) are multivalent linkers with two distinct types of single-stranded DNA (ssDNA) ends complementary to those ssDNAs on binary programmable atom equivalents (PAEs). We derive a statistical mechanical… ▽ More To unlock the potential for assembling complex colloidal "molecules", we investigate a minimal binary system of programmable colloidal atom-electron equivalents (PAE-EE), where electron equivalents (EEs) are multivalent linkers with two distinct types of single-stranded DNA (ssDNA) ends complementary to those ssDNAs on binary programmable atom equivalents (PAEs). We derive a statistical mechanical framework for calculating the effective interaction between PAEs mediated by EEs with arbitrary valency, which quantitatively agrees with simulations that explicitly include EEs. Our analysis reveals an anomalous dependence of PAE-PAE interactions on the EE valency, showing that EE-mediated interactions converge at the large valency limit. Moreover, we identify an optimal EE valency that maximizes the interaction difference between targeted and non-targeted binding pairs of PAEs. These findings offer design principles for targeted self-assembly in PAE-EE systems. △ Less

Submitted 9 June, 2025; v1 submitted 31 October, 2024; originally announced October 2024.

Journal ref: Rep. Prog. Phys., 88, 078101 (2025)

A new approach to N-doped di-molybdenum carbide with enhanced superconductivity via Urea

Authors: Longfu Li, Lei Shi, Lingyong Zeng, Kuan Li, Peifeng Yu, Kangwang Wang, Chao Zhang, Rui Chen, Zaichen Xiang, Yunwei Zhang, Huixia Luo

Abstract: Chemical doping is a critical factor in the development of new superconductors or optimizing the superconducting transition temperature (Tc) of the parent superconducting materials. Herein, a new simple urea approach is developed to synthesize the N-doped alfa-Mo2C. Benefiting from the simple urea method, a broad superconducting dome is found in the Mo2C1-xNx compositions. XRD results show that th… ▽ More Chemical doping is a critical factor in the development of new superconductors or optimizing the superconducting transition temperature (Tc) of the parent superconducting materials. Herein, a new simple urea approach is developed to synthesize the N-doped alfa-Mo2C. Benefiting from the simple urea method, a broad superconducting dome is found in the Mo2C1-xNx compositions. XRD results show that the structure of alfa-Mo2C remains unchanged and that there is a variation of lattice parameters with nitrogen doping. Resistivity, magnetic susceptibility, and heat capacity measurement results confirm that the superconducting transition temperature (Tc) was strongly increased from 2.68 K (x = 0) to 7.05 K (x = 0.49). First-principles calculations and our analysis indicate that increasing nitrogen doping leads to a rise in the density of states at the Fermi level and doping-induced phonon softening, which enhances electron-phonon coupling. This results in an increase in Tc and a sharp rise in the upper critical field. Our findings provide a promising strategy for fabricating transition metal carbonitrides and provide a material platform for further study of the superconductivity of transition metal carbides. △ Less

Submitted 19 October, 2024; originally announced October 2024.

Comments: 15 pages, 6 Figures, 1 Table

Journal ref: Chin. Phys. Lett. 2024

Quantum metric driven transition between superfluid and incoherent fluid

Authors: Xuzhe Ying, Kangle Li

Abstract: We study the interplay between repulsive interaction and superfluidity in flat band system. We consider spatially indirect excitons in the Lieb lattice bilayer as an example. We show that due to the presence of repulsive interaction, the excitons may form an incoherent fluid. By increasing the quantum metric, the exciton fluid experiences a transition into the superfluid phase. Such transition may… ▽ More We study the interplay between repulsive interaction and superfluidity in flat band system. We consider spatially indirect excitons in the Lieb lattice bilayer as an example. We show that due to the presence of repulsive interaction, the excitons may form an incoherent fluid. By increasing the quantum metric, the exciton fluid experiences a transition into the superfluid phase. Such transition may be captured by a model of Josephson junction array, which is beyond mean field description. △ Less

Submitted 16 October, 2024; originally announced October 2024.

Comments: Maintext: 6 pages, 4 figures; Supplemental material: 8 pages, 1 figure

Journal ref: Phys. Rev. B 112, 014518(2025)

Evaluating the Performance and Robustness of LLMs in Materials Science Q&A and Property Predictions

Authors: Hongchen Wang, Kangming Li, Scott Ramsay, Yao Fehlis, Edward Kim, Jason Hattrick-Simpers

Abstract: Large Language Models (LLMs) have the potential to revolutionize scientific research, yet their robustness and reliability in domain-specific applications remain insufficiently explored. In this study, we evaluate the performance and robustness of LLMs for materials science, focusing on domain-specific question answering and materials property prediction across diverse real-world and adversarial c… ▽ More Large Language Models (LLMs) have the potential to revolutionize scientific research, yet their robustness and reliability in domain-specific applications remain insufficiently explored. In this study, we evaluate the performance and robustness of LLMs for materials science, focusing on domain-specific question answering and materials property prediction across diverse real-world and adversarial conditions. Three distinct datasets are used in this study: 1) a set of multiple-choice questions from undergraduate-level materials science courses, 2) a dataset including various steel compositions and yield strengths, and 3) a band gap dataset, containing textual descriptions of material crystal structures and band gap values. The performance of LLMs is assessed using various prompting strategies, including zero-shot chain-of-thought, expert prompting, and few-shot in-context learning. The robustness of these models is tested against various forms of 'noise', ranging from realistic disturbances to intentionally adversarial manipulations, to evaluate their resilience and reliability under real-world conditions. Additionally, the study showcases unique phenomena of LLMs during predictive tasks, such as mode collapse behavior when the proximity of prompt examples is altered and performance recovery from train/test mismatch. The findings aim to provide informed skepticism for the broad use of LLMs in materials science and to inspire advancements that enhance their robustness and reliability for practical applications. △ Less

Submitted 11 March, 2025; v1 submitted 22 September, 2024; originally announced September 2024.

Spin Dynamics in Hybrid Halide Perovskites -- Effect of Dynamical and Permanent Symmetry Breaking

Authors: Kejun Li, Junqing Xu, Uyen N. Huynh, Rikard Bodin, Mayank Gupta, Christian Multunas, Jacopo Simoni, Ravishankar Sundararaman, Zeev Valy Verdany, Yuan Ping

Abstract: The hybrid organic-inorganic halide perovskite (HOIP), for example MAPbBr3, exhibits extended spin lifetime and apparent spin lifetime anisotropy in experiments. The underlying mechanisms of these phenomena remain illusive. By utilizing our first-principles densitymatrix dynamics approach with quantum scatterings including electron-phonon and electronelectron interactions and self-consistent spino… ▽ More The hybrid organic-inorganic halide perovskite (HOIP), for example MAPbBr3, exhibits extended spin lifetime and apparent spin lifetime anisotropy in experiments. The underlying mechanisms of these phenomena remain illusive. By utilizing our first-principles densitymatrix dynamics approach with quantum scatterings including electron-phonon and electronelectron interactions and self-consistent spinorbit coupling, we present temperature- and magnetic field-dependent spin lifetimes in hybrid perovskites, in agreement with experimental observations. For centrosymmetric hybrid perovskite MAPbBr3, the experimentally observed spin lifetime anisotropy is mainly attributed to the dynamical Rashba effect arising from the interaction between organic and inorganic components and the rotation of the organic cation. For noncentrosymmetric perovskite, such as MPSnBr3, we found persistent spin helix texture at the conduction band minimum, which significantly enhances the spin lifetime anisotropy. Our study provides theoretical insight to spin dynamics in HOIP and strategies for controlling and optimizing spin transport. △ Less

Submitted 20 September, 2024; originally announced September 2024.

Scalable Reshaping of Diamond Particles via Programmable Nanosculpting

Authors: Tongtong Zhang, Fuqiang Sun, Yaorong Wang, Yingchi Li, Jing Wang, Zhongqiang Wang, Kwai Hei Li, Ye Zhu, Qi Wang, Lei Shao, Ngai Wong, Dangyuan Lei, Yuan Lin, Zhiqin Chu

Abstract: Diamond particles have many interesting properties and possible applications. However, producing diamond particles with well-defined shapes at scale is challenging because diamonds are chemically inert and extremely hard. Here, we show air oxidation, a routine method for purifying diamonds, can be used to precisely shape diamond particles at scale. By exploiting the distinct reactivities of differ… ▽ More Diamond particles have many interesting properties and possible applications. However, producing diamond particles with well-defined shapes at scale is challenging because diamonds are chemically inert and extremely hard. Here, we show air oxidation, a routine method for purifying diamonds, can be used to precisely shape diamond particles at scale. By exploiting the distinct reactivities of different crystal facets and defects inside the diamond, layer-by-layer outward-to-inward and inward-to-outward oxidation produced diverse diamond shapes including sphere, twisted surface, pyramidal islands, inverted pyramids, nano-flowers, and hollow polygons. The nanosculpted diamonds had more and finer features that enabled them to outperform the original raw diamonds in various applications. Using experimental observations and Monte Carlo simulations, we built a shape library that guides the design and fabrication of diamond particles with well-defined shapes and functional value. Our study presents a simple, economical and scalable way to produce shape-customized diamonds for various photonics, catalysis, quantum and information technology applications. △ Less

Submitted 14 September, 2024; originally announced September 2024.

Single nuclear spin detection and control in a van der Waals material

Authors: Xingyu Gao, Sumukh Vaidya, Kejun Li, Zhun Ge, Saakshi Dikshit, Shimin Zhang, Peng Ju, Kunhong Shen, Yuanbin Jin, Yuan Ping, Tongcang Li

Abstract: Optically active spin defects in solids are leading candidates for quantum sensing and quantum networking. Recently, single spin defects were discovered in hexagonal boron nitride (hBN), a layered van der Waals (vdW) material. Due to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale… ▽ More Optically active spin defects in solids are leading candidates for quantum sensing and quantum networking. Recently, single spin defects were discovered in hexagonal boron nitride (hBN), a layered van der Waals (vdW) material. Due to its two-dimensional structure, hBN allows spin defects to be positioned closer to target samples than in three-dimensional crystals, making it ideal for atomic-scale quantum sensing, including nuclear magnetic resonance (NMR) of single molecules. However, the chemical structures of these defects remain unknown, and detecting a single nuclear spin with an hBN spin defect has been elusive. In this study, we created single spin defects in hBN using $^{13}$C ion implantation and identified three distinct defect types based on hyperfine interactions. We observed both S=1 and S=1/2 spin states within a single hBN spin defect. We demonstrated atomic-scale NMR and coherent control of individual nuclear spins in a vdW material, with a $π$-gate fidelity up to 99.75% at room temperature. By comparing experimental results with density-functional theory calculations, we propose chemical structures for these spin defects. Our work advances the understanding of single spin defects in hBN and provides a pathway to enhance quantum sensing using hBN spin defects with nuclear spins as quantum memories. △ Less

Submitted 31 May, 2025; v1 submitted 3 September, 2024; originally announced September 2024.

Comments: 12 pages, 6 figures

Journal ref: Nature 643, 943 (2025)

Localized tension-induced giant folding in unstructured elastic sheets

Authors: Kexin Guo, Marc Suñé, Kwok Ming Li, K. Jimmy Hsia, Mingchao Liu, Dominic Vella

Abstract: Buckling in compression is the archetype of elastic instability: when compressed along its longest dimension, a thin structure such as a playing card will buckle out-of-plane accommodating the imposed compression without a significant change of length. However, recent studies have demonstrated that tension applied to sheets with microscopic structure leads to out-of-plane deformation in applicatio… ▽ More Buckling in compression is the archetype of elastic instability: when compressed along its longest dimension, a thin structure such as a playing card will buckle out-of-plane accommodating the imposed compression without a significant change of length. However, recent studies have demonstrated that tension applied to sheets with microscopic structure leads to out-of-plane deformation in applications from `groovy metasheets' for multi-stable morphing to kirigami grippers. Here, we demonstrate that this counter-intuitive behavior -- a large transverse folding induced by a relatively small imposed longitudinal tension -- occurs also in unstructured sheets of isotropic material. The key to this behavior is that a localized uniaxial tension induces giant folding; we refer to this as `localized TUG folding' to reflect the importance of localized tension and its mode of actuation. We show that localized TUG folding occurs because of an efficient transfer of applied tensile load into compression -- a geometric consequence of a localized applied tension. We determine scaling results for the folding angle as a function of applied strain in agreement with both experiments and simulations. The generic nature of localized TUG folding suggests that it might be utilized in a broader range of materials and structures than previously realized. △ Less

Submitted 3 April, 2025; v1 submitted 26 August, 2024; originally announced August 2024.

Comments: 8 pages and 4 figures of main text; 14 pages of supplementary information

Journal ref: Proc. Natl Acad. Sci. USA 122, e2423439122 (2025)

Excellent and CO$_2$$_{0.85}$Nd$_{0.1}$Cu$_{0.05}$O$_{2-δ}$-Nd$_x$Sr$_{1-x}$Fe$_{1-y}$Cu$_y$O$_{3-δ}$ dual-phase oxygen transport membranes

Authors: Chao Zhang, Yue Zhu, Xiaopeng Wang, Yanhao Huang, Lingyong Zeng, Kuan Li, Peifeng Yu, Kangwang Wang, Longfu Li, Zaichen Xiang, Rui Chen, Xuefeng Zhu, Huixia Luo

Abstract: Oxygen transport membranes(OTMs)have provided great opportunities in the last decades but are suffering from the trade-off effect between stability and oxygen permeability. Here, we report a group of new planar dual-phase mixed ionic-electronic conducting (MIEC) OTMs consisting of CO$_2$$_{0.85}$Nd$_{0.1}$Cu$_{0.05}$O$_2$ (CNCO) and Nd$_x$Sr$_{1-x}$Fe$_{1-y}$Cu$_y$O$_3$(NSFCO; $x = 0.4, 0.6$;… ▽ More Oxygen transport membranes(OTMs)have provided great opportunities in the last decades but are suffering from the trade-off effect between stability and oxygen permeability. Here, we report a group of new planar dual-phase mixed ionic-electronic conducting (MIEC) OTMs consisting of CO$_2$$_{0.85}$Nd$_{0.1}$Cu$_{0.05}$O$_2$ (CNCO) and Nd$_x$Sr$_{1-x}$Fe$_{1-y}$Cu$_y$O$_3$(NSFCO; $x = 0.4, 0.6$; $y = 0.05, 0.1$) phases, showing excellent oxygen permeability while comparable CO$_2$-resistant stability. The substitution of Cu as a bifunctional additive decreases the sintering temperature and enhances bulk diffusion and oxygen permeability with the co-doping of Nd.The oxygen permeation fluxes reached 2.62 and 1.52 mL min$^{-1}$ cm$^{-2}$ at 1000$^\circ$C through the optimal 60wt%Ce0.85Nd0.1Cu0.05O2-40wt%Nd0.4Sr0.6Fe0.9Cu0.1O3 (CNCO-NSFCO41) composition with He and CO$_2$ sweeping, respectively, higher than all reported dense dual-phase OTMs. Such excellent CO$_2$-tolerant permeability meets the needs of potential industrial applications. Analysis with Zhu's oxygen permeation model shows lower bulk diffusion resistance of CNCO-NSFCO41 than that of reported 60wt%Ce0.85Pr0.1Cu0.05O2-40wt%Pr0.4Sr0.6Fe0.9Cu0.1O3(CPCO-PSFCO41)and more limitation by the interfacial exchange at high temperature. All the prepared OTMs also show good long-term stability over 100 hours in both atmospheres. Our results confirm the excellent oxygen permeability and stability under a high-concentration CO2 atmosphere, providing a material candidate for CO2 capture in oxyfuel combustion. △ Less

Submitted 22 August, 2024; originally announced August 2024.

Comments: 36 pages, 6 figures

Journal ref: Journal of Membrane Science, 2024,696,122485