CMP Journal 2025-11-28
Statistics
Nature Materials: 2
Nature Physics: 1
arXiv: 66
Nature Materials
Super-expansive thermo-reversible interstitial solid solution of nanocrystal superlattices with mesogens
Original Paper | Coarse-grained models | 2025-11-27 19:00 EST
Shengsong Yang, Dai-Bei Yang, Yifan Ning, Yugang Zhang, James M. Kikkawa, Jeffery G. Saven, Christopher B. Murray
Designing superlattices of nanocrystals to mimic and extend the properties of atomic crystals has been a long-standing motivation in materials chemistry. Interstitial solid solutions, such as steel, are well-studied atomic lattices in which mobile components move among the interstices. These materials exhibit unique properties, including reversible structural changes and phase transitions. Interstitial solid solutions possess unique dynamic structures and reversible responses, which motivate the creation of their colloidal equivalents. Here we report a fully thermo-reversible colloidal interstitial solid solution by combining liquid crystals and nanocrystals functionalized with promesogenic ligands. Mesogen molecules fill and diffuse among the interstices of a superlattice, resulting in a super-large thermal expansivity. The approach uses a modular design of interparticle interactions, allowing control of interparticle distance, microstructure and transition between crystallographic forms.
Coarse-grained models, Liquid crystals, Nanoparticles, Self-assembly, Structural properties
Self-assembled cell-scale containers made from DNA origami membranes
Original Paper | DNA nanostructures | 2025-11-27 19:00 EST
Christoph Karfusehr, Markus Eder, Hao Yuan Yang, Brice Beinsteiner, Marion Jasnin, Friedrich C. Simmel
Biological compartmentalization creates and controls localized environments to ensure that chemical processes are efficient, thus enabling life’s complexity and functionality. Biological systems use crystalline protein cages for nanoscale compartments, whereas larger, dynamic structures, such as vesicles and cell membranes, are formed from lipid bilayers. Although membrane-based approaches have prevailed in bottom-up synthetic biology, DNA and protein nanotechnology has focused on designing rigid cage assemblies. Here we report on the self-assembly of radially symmetric DNA origami subunits that are inspired by the structure and interactions of lipids. The formed DNA origami monolayer membranes can be readily programmed to form vesicles or hollow tubes with diameters ranging from 100 nm to over 1 μm. These DNA origami membranes represent an approach for compartmentalization that opens possibilities in bottom-up biology and cell-scale soft robotics.
DNA nanostructures, Membrane structure and assembly
Nature Physics
Quantum superconducting diode effect with perfect efficiency above liquid-nitrogen temperature
Original Paper | Superconducting devices | 2025-11-27 19:00 EST
Heng Wang, Yuying Zhu, Zhonghua Bai, Zhaozheng Lyu, Jiangang Yang, Lin Zhao, X. J. Zhou, Qi-Kun Xue, Ding Zhang
The superconducting diode is a device that allows supercurrent to flow in one direction but not the other. Usually, the state that does not allow supercurrent has no Cooper pairs. Here we report a quantized version of the superconducting diode that operates solely between Cooper-paired states. This type of quantum superconducting diode takes advantage of quantized Shapiro steps for digitized output. The device consists of twisted high-temperature cuprate superconductors and exhibits the following characteristics. First, we show that a non-reciprocal diode behaviour can be initiated by training with current pulses without applying an external magnetic field. Then, we demonstrate perfect diode efficiency under microwave irradiation above liquid-nitrogen temperature. Lastly, the quantized nature of the output offers high resilience against input noise. These features open up opportunities to develop practical dissipationless quantum circuits.
Superconducting devices, Superconducting properties and materials
arXiv
Vacancy Engineering in Metals and Alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Sreenivas Raguraman, Homero Reyes Pulido, Christopher Hutchinson, Arun Devaraj, Marc H. Weber, Timothy P. Weihs
Vacancy engineering, the intentional control of atomic-scale vacancies in metals and alloys, is emerging as a powerful yet underexplored strategy for tailoring microstructures and optimizing performance across diverse applications. By enabling excess vacancy populations through quenching, severe deformation, thermomechanical treatments, or additive manufacturing, new microstructures can be obtained that achieve unique combinations of strength, ductility, fatigue life, corrosion resistance, and conductivity. Vacancies are distinct among lattice defects: they are non-conserved entities essential for solute diffusion, yet variably coupled to solutes, dislocations, and phase boundaries. They can accelerate transformations such as nucleation and precipitation or retard kinetics when trapped in clusters, and their transient trapping and release can drive microstructural evolution across time and length scales. This Review synthesizes recent advances in generating, modeling, and characterizing vacancies, highlighting their role in diffusion, precipitation, and phase stability. Case studies in lightweight, high-temperature, fatigue-resistant, electrical, and biomedical materials demonstrate the broad potential of vacancy control. We conclude by emphasizing the opportunity for the metallurgical community to fully exploit excess vacancies as controllable, design-relevant defects that enable new pathways for microstructure and property optimization in next-generation alloys.
Materials Science (cond-mat.mtrl-sci)
21 pages, 5 display items
Towards superior van der Waals density functionals for molecular crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Dmitry V. Fedorov, Nikita E. Rybin, Mikhail A. Averyanov, Alexander V. Shapeev, Artem R. Oganov, Carlo Nervi
Ubiquitous van der Waals (vdW) interactions play a subtle yet crucial role in determining the precise atomic arrangements in solids, particularly in molecular crystals where these weak forces are the primary link between constituent building blocks. Within density functional (DF) theory, the most natural approach for addressing vdW forces is the use of vdW-inclusive density functionals. Through a detailed analysis of the underlying formalism, we have developed a computational scheme that combines vdW functionals of type DF1 and DF2 and serves as a well optimizable tool to improve the theoretical description and prediction of molecular crystals and other sparse materials. The proof of principle is demonstrated by our consideration of the molecular crystals from the X23 dataset.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
6 pages, 3 figures
CHIPS-TB: Evaluating Tight-Binding Models For Metals, Semiconductors, and Insulators
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
As semiconductor technologies continue to scale down to the nanoscale, the efficient prediction of material properties becomes increasingly critical. The tight-binding (TB) method is a widely used semi-empirical approach that offers a computationally tractable alternative to Density Functional Theory (DFT) for large-scale electronic structure calculations. However, conventional TB models often suffer from limited transferability and lack standardized benchmarking protocols. In this study, we introduce a computational framework (CHIPS-TB) for evaluating and comparing tight-binding parameterizations across diverse material systems relevant to semiconductor design, focusing on properties such as electronic bandgaps, band structures, and bulk modulus. We assess model parameterizations including Density Functional Tight-Binding (DFTB)-based MatSci, PBC, PTBP, SlaKoNet and TB3PY against OptB88vdW, TBmBJ-DFT and experimental reference data from the JARVIS-DFT database for 50+ materials pertinent to semiconductor applications. The CHIPS-TB code will be made publicly available on GitHub and benchmarks will be available on JARVIS-Leaderboard.
Materials Science (cond-mat.mtrl-sci)
Light-induced Asymmetric Pseudogap below T$_\text{c}$ in cuprates
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-27 20:00 EST
D. Armanno, O. Gingras, F. Goto, J.-M. Parent, A. Longa, A. Jabed, B. Frimpong, R.D. Zhong, J. Schneeloch, G. D. Gu, G. Jargot, H. Ibrahim, F. Legare, B.J. Siwick, N. Gauthier, A. Georges, A.J. Millis, F. Boschini
To this day, high-temperature cuprate superconductors remain an unparalleled platform for studying the competition and coexistence of emergent, static and dynamic, quantum phases of matter exhibiting high transition temperature non-s-wave superconductivity, non-Fermi liquid transport and a still enigmatic pseudogap regime. However, how superconductivity emerges alongside and competes with the pseudogap regime remains an open question. Here, we present a high-resolution, time- and angle-resolved photoemission study of the near-antinodal region of optimally-doped Bi$ _2$ Sr$ _2$ CaCu$ _2$ O$ _{8+\delta}$ . For a sufficiently high excitation fluence, we disrupt superconductivity and drive a transient change from a symmetric superconducting-like to an asymmetric pseudogap-like density of states, for electronic temperatures well below the equilibrium superconducting critical temperature. Conversely, when the superconductivity is fully restored, the pseudogap is suppressed, as signaled by a fully particle-hole symmetric density of states. A unique aspect of our experiments is that the pseudogap coexists with superconducting features at intermediate times or at intermediate fluence. Our findings challenge the paradigm that superconductivity emerges by establishing phase coherence in the pseudogap. Instead, our experimental results, supported by phenomenological theory, demonstrate that the two states compete, and that the low-temperature ground state of the cuprates originates from a competition between superconducting and pseudogap states.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Strong-coupling theory of bilayer plasmon excitations
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Hiroyuki Yamase, Luciano Zinni, Matías Bejas, Andrés Greco
Recently plasmon excitations in bilayer lattice systems were studied extensively in the weak-coupling regime. Unlike single-layer systems, these bilayers exhibit two distinct modes, $ \omega_{\pm}$ , which show characteristic dependences upon the momentum and hopping integrals along the $ z$ direction. To apply them to cuprates, strong correlation effects should be considered, but a comprehensive analysis has not yet been investigated. In this work, we present a strong-coupling theory to analyze the charge dynamics of a bilayer system, utilizing the $ t$ -$ J$ -$ V$ model, which includes the long-range Coulomb interaction, $ V$ , on a lattice. Although our theoretical framework is fundamentally different from the weak-coupling approach, we find that resulting plasmon excitations are similar to those of a weak-coupling theory. A key distinction is that our strong-coupling framework reveals a noticeable suppression of particle-hole excitations, which allows the plasmon modes to remain well-defined over a wider region of momentum. We suggest that the experimentally reported plasmon excitations in Y-based cuprates can be described by the $ \omega_{-}$ mode, although we call for more systematic experiments to verify this.
Strongly Correlated Electrons (cond-mat.str-el)
Memory Effects in Contact Line Friction
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Niklas Wolf, Nico van der Vegt
When a drop of liquid comes into contact with a solid surface, it relaxes towards an equilibrium configuration, either wetting the surface or remaining in a droplet-like shape with a finite contact angle. The force driving the process towards equilibrium is the corresponding out-of-balance Young’s force. However, the speed with which the liquid front advances depends strongly on an opposing friction force arising from dissipative processes due to the moving solid-liquid-gas contact line. In analogy to the treatment of hydrodynamic friction we present an exact method, based on the Mori-Zwanzig formalism, to extract this friction from equilibrium data. We find that the contact line exhibits long-lasting memory with a characteristic power-law decay due to coupling to the systems hydrodynamic modes. Within linear response regime, we obtain the frequency-dependent dissipative and elastic response of the contact line to an external perturbation, including a frequency-dependent friction coefficient. Similar to hydrodynamic friction in liquids, we find that the friction decreases beyond a characteristic frequency and the system exhibits predominantly elastic behavior.
Soft Condensed Matter (cond-mat.soft)
Hund-projected Kanamori model: an effective description of Hund’s metals near the Mott insulating regime
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Hund’s coupling plays a decisive role in shaping electron correlations of multi-orbital systems, giving rise to a class of materials–Hund’s metals–that combine local-moment physics with metallic transport. Here we derive an effective low-energy description of such a system near the Mott insulating regime, starting from the multi-orbital Hubbard-Kanamori Hamiltonian and projecting onto the high-spin manifold favored by Hund’s first rule. The resulting Hund-projected Kanamori model captures the interplay between carrier motion and magnetic correlations in the presence of strong Hund’s coupling. In the undoped limit, the model reduces to a spin-$ N/2$ Heisenberg system with suppressed quantum fluctuations, approaching the classical limit for realistic five-band configurations. Upon doping, carrier motion couples strongly to the spin background and drives ferromagnetic correlations through a Hund-enhanced kinetic mechanism analogous to, but much stronger than, Nagaoka ferromagnetism. Owing to its reduced sign problem, the model can be addressed with advanced path-integral methods to determine quasiparticle structure and effective interactions between carriers-quantities that are challenging to obtain with other methods. This framework establishes a microscopic bridge between the Kanamori model and the emergent magnetic and transport phenomena characteristic of Hund’s metals.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Analytical Interaction Potentials for Disks in Two Dimensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Binghan Liu, Junwen Wang, Gary S. Grest, Shengfeng Cheng
Compact analytical forms are derived for the interactions involving thin disks in two dimensions using an integration approach. These include interactions between a disk and a material point, between two disks, and between a disk and a wall. Each object is treated as a continuous medium of materials points interacting by the Lennard-Jones 12-6 potential. By integrating this potential in a pairwise manner, expressions for the potentials and resultant forces between extended objects are obtained. All the results are validated with numerical integrations. The analytical potentials are implemented in LAMMPS and used to simulate two-dimensional suspension of disks with an explicit solvent modeled as a Lennard-Jones liquid. In monodisperse disk suspensions, a disorder-to-order transition of disk packing is observed as the area fraction of disks is increased or as the solvent evaporates. In bidisperse disk suspensions being rapidly dried, stratification is found with the smaller disks enriched at the evaporation front. Such “small-on-top” stratification echoes the similar phenomenon occurring in three-dimensional polydisperse colloidal suspensions that undergo fast drying. These potentials can be applied to a wide range of two-dimensional systems involving disk-like objects.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
14 pages, 8 figures, 14 page Supporting Information with 9 figures
The metastability of lipid vesicle shapes in uniaxial extensional flow
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
M.A. Shishkin (1 and 2), E.S. Pikina (1 and 3) ((1) Landau Institute for Theoretical Physics Russia, (2) HSE University Russia, (3) Oil and Gas Research Institute Russia)
In this work, we investigate the elastic properties of deflated vesicles and their shape dynamics in uniaxial extensional flow. By analysing the Helfrich bending energy and viscous flow stresses in the limit of highly elongated shapes, we demonstrate that all stationary vesicle configurations are metastable. For vesicles with small reduced volume, we identify the type of bifurcation at which the stationary state is lost, leading to unbounded vesicle elongation in time. We show that the stationary vesicle length remains finite at the critical extension rate. The critical behaviour of the stationary vesicle length and of the growth rates of small perturbations is obtained analytically and confirmed by direct numerical computations. The beginning stage of the unbounded elongation dynamics is simulated numerically, in agreement with the analytical predictions.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
15 pages, 12 figures
A new Fractal Mean-Field analysis in phase transition
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Ismael S. S. Carrasco, Henrique A. de Lima, Fernando A. Oliveira
Understanding phase transitions requires not only identifying order parameters but also characterizing how their correlations behave across scales. By quantifying how fluctuations at distinct spatial or temporal points are related, correlation functions reveal the structural organization of complex systems. Here, we revisit the theoretical foundations of these correlations in systems undergoing second-order phase transitions, with emphasis on the Ising model extended to non-integer spatial dimensions. Starting from the classical framework introduced by Fisher, we discuss how the standard Euclidean treatment, restricted to integer dimensions, necessitates the introduction of the critical exponent $ \eta$ to capture the spatial decay of correlations at $ T=T_c$ . We suppose that, at criticality, the equilibrium dynamics become effectively confined to the fractal edge of spin clusters. Within this framework, the fractal dimension that governs the correlations in that subspace is directly related to Fisher exponent, which quantifies the singular behavior of the correlation function near criticality. Importantly, this correlation fractal dimension is distinct from the fractal dimension associated with the order parameter. We further derive an explicit geometrical relation connecting the two fractal dimensions, thereby linking spatial self-similarity to the observed scaling behavior at criticality. This treatment naturally extends to non-integer spatial dimensions, which remain valid below the upper critical dimension and produce the correct value of Fisher exponent $ \eta$ for a continuous space dimension. Our analysis also confirms that the Rushbrooke scaling relation, continues to hold when the spatial dimension is treated as a continuous parameter, reinforcing the universality of critical scaling and underscoring the role of fractal geometry in characterizing correlations at criticality.
Statistical Mechanics (cond-mat.stat-mech)
Defect Bootstrap: Tight Ground State Bounds in Spontaneous Symmetry Breaking Phases
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Michael G. Scheer, Nisarg Chadha, Da-Chuan Lu, Eslam Khalaf
The recent development of bootstrap methods based on semidefinite relaxations of positivity constraints has enabled rigorous two-sided bounds on local observables directly in the thermodynamic limit. However, these bounds inevitably become loose in symmetry broken phases, where local constraints are insufficient to capture long-range order. In this work, we identify the origin of this looseness as order parameter defects which are difficult to remove using local operators. We introduce a $ \textit{defect bootstrap}$ framework that resolves this limitation by embedding the system into an auxiliary $ \textit{defect model}$ equipped with ancilla degrees of freedom. This construction effectively enables local operators to remove order parameter defects, yielding tighter bounds in phases with spontaneous symmetry breaking. This approach can be applied broadly to pairwise-interacting local lattice models with discrete or continuous internal symmetries that satisfy a property we call $ \textit{defect diamagnetism}$ , which requires that the ground state energy does not decrease upon adding any finite number of symmetry defects. Applying the method to the transverse field Ising models in 1D and 2D, we obtain significantly improved bounds on energy densities and spin correlation functions throughout the symmetry broken phase in 1D and deep within the phase in 2D. Our results demonstrate that physically motivated constraint sets can dramatically enhance the power of bootstrap methods for quantum many-body systems.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
9 pages, 5 figures
Cr2O3/\b{eta}-Ga2O3 Heterojunction Diodes with Orientation-Dependent Breakdown Electric Field up to 12.9 MV/cm
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Yizheng Liu, Haochen Wang, Carl Peterson, James S. Speck, Chris Van De Walle, Sriram Krishnamoorthy
We report the fabrication of Cr2O3/\b{eta}-Ga2O3 heterojunction diodes using reactive magnetron sputtering of Cr2O3 on highly doped \b{eta}-Ga2O3 bulk substrates along (100), (010), (001), (110), and (011) orientation dependence of high electric field handling capability in \b{eta}-Ga2O3. Additional relative permittivity values in (110) and (011) orientations of \b{eta}-Ga2O3 were computed by using first-principles calculation methods for accurate apparent charge density (ND-NA) extraction and breakdown electric field analysis from capacitance-voltage measurements. The HJDs fabricated on n+ (110) exhibited breakdown electric fields >10 MV/cm up to 12.9 MV/cm, showing the highest experimentally observed parallel-plane junction electric field among \b{eta}-Ga2O3-based junctions. Breakdown electric fields among (100), (010), (001), and (011) orientations showed distinct distribution in the range of 5.13-5.26 MV/cm, 5.10-7.05 MV/cm, 2.70-3.33 MV/cm, and 3.88-4.38 MV/cm, respectively, validating the orientational dependence of parallel-plane junction electric field at breakdown in low-symmetry monoclinic \b{eta}-Ga2O3. The parallel-plane breakdown electric fields (EBr,||) reported in this work were extracted when the device experienced catastrophic breakdown at 100 mA/cm^2 current density compliance, and should not be confused with critical electric field (Ec) as a function of drift layer doping concentration, which accounts for electric-field dependent impact ionization coefficients in Si, SiC and GaN. This study can guide the choice of crystal orientation for high performance gallium oxide-based devices that require high electric field handling capability.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Photo-induced carrier dynamics in InSb probed with broadband THz spectroscopy based on BNA crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Elodie Iglesis, Alexandr Alekhin, Maximilien Cazayous, Alain Sacuto, Yann Gallais, Sarah Houver
We report an optical pump - terahertz (THz) probe study of the photoinduced transient carrier dynamics in the low bandgap semiconductor Indium Antimonide (InSb). Using an organic N-benzyl-2-methyl-nitroaniline (BNA) crystal as a broadband THz source, we access the full spectral response over more than 5 THz, for varying pump-probe delay following the optical excitation. Using the Drude-Lorentz model accounting for differences between the excited length in material and the penetration depth of THz beam in pumped InSb, we extract the absolute carrier density as a function of the pump-probe delay, and provide insights on the diffusion length at given carrier densities, for different pump fluences. The mismatch between the THz penetration depth and the actual excited sample depth after carrier diffusion is discussed, since their evolutions with time and pump fluence are not intuitive as both quantities depend on carrier density.
Materials Science (cond-mat.mtrl-sci)
10 pages, 6 figures, 32 references
Hardware Acceleration of Frustrated Lattice Systems using Convolutional Restricted Boltzmann Machine
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Pratik Brahma, Junghoon Han, Tamzid Razzaque, Saavan Patel, Sayeef Salahuddin
Geometric frustration gives rise to emergent quantum phenomena and exotic phases of matter. While Monte Carlo methods are traditionally used to simulate such systems, their sampling efficiency is limited by the complexity of interactions and ground-state properties. Restricted Boltzmann Machines (RBMs), a class of probabilistic neural networks, offer improved sampling by incorporating machine learning techniques. However, fully-connected bipartite RBMs are inefficient for representing physical lattices with sparse interactions. To address this, we implement Convolutional Restricted Boltzmann Machines (CRBMs) that leverage translational symmetry inherent to lattices. Using the classical Shastry-Sutherland (SS) Ising lattice, we demonstrate (i) CRBM formulation that captures SS interactions, and (ii) digital hardware accelerator to enhance sampling performance. We simulate lattices with up to 324 spins, recovering all known phases of the SS Ising model, including the long range ordered fractional plateau. Our hardware characterizes spin behavior at critical points and within spin liquid phases. This implementation achieves a speedup of 3 to 5 orders of magnitude (33 ns to 120 ms) over GPU-based implementations. Moreover, the time-to-solution is within two orders of magnitude of quantum annealers, while offering superior scalability, room-temperature operation and reprogrammability. This work paves a pathway for scalable digital hardware that embeds physical symmetries to enable large scale simulations of material systems.
Statistical Mechanics (cond-mat.stat-mech)
Optical contrast-based determination of number of layers for two-dimensional van der Waals magnet Fe$_3$GeTe$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Neesha Yadav, Sandeep, Pintu Das
Recent advances in revealing intrinsic magnetism in two-dimensional (2D) materials have highlighted their potential for future spintronic applications, driven by their novel physical properties, promising for future spintronic devices. In order to explore layer dependent magnetic behavior, in general, mechanically exfoliated flakes from high-quality single crystals are used. It is crucial to determine the number of layers of these materials accurately. In the absence of an efficient and quick method, researchers often rely on atomic force microscopy (AFM) imaging to identify their number of layers. In this work, we report an optical contrast study as a quick and cost-effective technique to determine the number of layers of Fe$ _3$ GeTe$ _2$ (FGT). Here, we observed a linear relationship between the optical contrast (derived from optical microscopic images) observed for mechanically exfoliated FGT nano-flakes and their thickness, as measured by the AFM imaging method. This technique requires no additional equipment; it relies solely on a conventional optical microscope. Additionally, our results reveal a thickness-dependent evolution of the intensity; in contrast, the Raman frequency demonstrates no significant dependence on layer thickness. Also, our studies reveal two additional Raman modes of FGT, at the frequency of 129,cm$ ^-1$ & 190,cm$ ^-1$ . Both modes show the intensity dependence on the thickness of FGT, same as out-of-plane (A$ _{1g}$ ) Raman modes.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
4 figures
Exploring the Anomalous Nernst Effect in SrRuO$_3$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Anna Merin Francis, Avirup De, Abhijit Biswas, Lily Mandal, Pallavi Kushwaha, Sunil Nair
We investigate the anomalous Nernst effect in epitaxial SrRuO$ _3$ thin films grown on c-cut Al$ _2$ O$ _3$ substrates, and in a polycrystalline SrRuO$ _3$ slab. Through comprehensive measurements of the transverse thermoelectric response as a function of temperature and magnetic field, we observe a pronounced Nernst signal near $ T_c$ in the (111) oriented SrRuO$ _3$ thin films. The strong temperature and nontrivial field dependence underscore the pivotal role of the magnetic anisotropy in tuning the Berry curvature and, consequently, the anomalous Nernst effect in SrRuO$ _3$ .
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 4 figures
Hierarchical high-throughput screening of alkaline-stable lithium-ion conductors combining machine learning and first-principles calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Zhuohan Li, KyuJung Jun, Bowen Deng, Gerbrand Ceder
The advancement of solid-state batteries depends on the development of lithium-ion conductors that exhibit both high ionic conductivity and stability across a wide range of electrochemical and chemical conditions. In this paper, we investigate the chemical factors that control the stability of Li-NASICONs and garnets in highly alkaline aqueous environment. While this is of general importance, it is particularly important for the operation of Li-air cells with humidified air. Humid air promotes the formation of LiOH as the discharge product, creating a highly alkaline environment on the surface of cathode and solid-state electrolyte. In this work, we combine machine learning and first-principles calculations to conduct a high-throughput computational screening of alkaline-stable oxide-based Li-ion conductors in order to better characterize the tradeoff between the various relevant properties. We evaluate the material stability in terms of pH, voltage, and species present in the environment (LiOH and H2O) across a vast range of chemical compositions with NASICON and garnet crystal structures. We utilize the CHGNet universal machine learning interatomic potential for pre-screening, followed by DFT calculations. Such a hierarchical screening procedure enables the evaluation of over 320,000 chemical compositions, encompassing nearly the entire periodic table. From this set 209 alkaline-stable NASICON and garnet compounds are selected as final candidates. We identify the specific cation substitutions that improve alkaline stability in NASICON and garnet compounds, and reveal the underlying mechanism. We also discover the trade-offs for designing alkaline-stable Li-ion conductors, highlighting the need to carefully optimize compositions so that it can simultaneously enhance all the material properties required for practical battery applications.
Materials Science (cond-mat.mtrl-sci)
Anisotropic scale invariance and the uniaxial Lifshitz point from the nonperturbative renormalization group
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Gonzalo De Polsi, Pawel Jakubczyk
We employ the derivative expansion of the nonperturbative renormalization group to address the phenomenon of anisotropic scale invariance and the associated functional fixed points, also known as Lifshitz points, in systems characterized by a scalar order parameter. We demonstrate the existence of the Lifshitz fixed point featuring a non-classical value of the anisotropy exponent $ \theta<1/2$ and provide estimates for values of a set of critical exponents in the physically most relevant case of the three-dimensional uniaxial Lifshitz point $ (d,m)=(3,1)$ , $ m$ denoting the anisotropy index. We compare our predictions with existing estimates from perturbative expansions around dimensionality $ d=4+\frac{1}{2}$ as well as those from the $ 1/N$ expansion.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Theory (hep-th)
11 pages, 6 figures, 1 supplemental (notebook file)
Ion Jump Motion as the Background for Muon Diffusion in Battery Materials Research Using $μ$SR
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
It is shown by numerical simulations of muon spin relaxation ($ \mu$ SR) spectra and analysis of these using the Kubo-Toyabe relaxation function $ G_z^{\rm KT}(t)$ that the anomalous peak in the fluctuation rate $ \nu_{\rm KT}$ around a specific temperature $ T^\ast$ and associated decrease of the linewidth $ \Delta_{\rm KT}$ above $ T^\ast$ , often observed in the previous $ \mu$ SR studies on ion diffusion, originate from the sharp increase in the ion jump rate $ \nu_{\rm i}$ against that of the muon $ \nu_\mu$ with increasing temperature. This indicates that a more detailed reanalysis of the vintage data using the “extended” Kubo-Toyabe relaxation function $ G_z^{\rm EA}(t)$ incorporating the jump motion of both ions and implanted muon (which was also used to simulate the $ \mu$ SR spectra) is useful for the proper evaluation of $ \nu_{\rm i}$ and $ \nu_\mu$ . Meanwhile, it also suggests that the $ \mu$ SR results showing no such anomaly convey little information on ion diffusion.
Materials Science (cond-mat.mtrl-sci)
5 pages, 3 figures
Self-avoiding walks pulled at an angle
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
C J Bradly, N R Beaton, A L Owczarek
We investigate polymers pulled away from an interacting surface, where the force is applied to the untethered endpoint and at an angle $ \theta$ to the surface. We use the canonical self-avoiding walk model of polymers and obtain the phase diagram of the model using Monte Carlo simulations for a range of angles, temperatures and force magnitudes. The phase diagram of the model displays re-entrance at low temperatures for three-dimensional walks when the pulling is more vertical than horizontal. Our results agree with various exactly solvable lattice models that have been previously studied.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
15 pages, 6 figures
Probing magnetic-field-induced multipolar ordering through field-angle-resolved magnetostriction and thermal expansion in PrIr$2$Zn${20}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Naoki Okamoto, Yohei Kono, Takahiro Onimaru, Keisuke T. Matsumoto, Kazumasa Hattori, Shunichiro Kittaka
We performed field-angle-resolved magnetostriction and thermal-expansion measurements on PrIr$ 2$ Zn$ {20}$ , a cubic non-Kramers compound exhibiting antiferroquadrupolar order below $ T{\rm Q}=0.125$ K. Thermal expansion exhibits two qualitatively different anomalies under magnetic fields applied along the $ [001]$ direction, providing experimental support for the existence of an intermediate A phase previously reported. Furthermore, comparison between the experimental results and theoretical modeling indicates a strong anisotropic coupling of the $ O{20}$ quadrupolar moment, which plays a key role in stabilizing the A phase. These findings demonstrate that multipolar states in non-Kramers systems can be effectively tuned by magnetic-field orientation, providing insights into the anisotropic nature of quadrupolar interactions.
Strongly Correlated Electrons (cond-mat.str-el)
6 pages, 5 figures, accepted for publication in Phys. Rev. B
Edge-state transport in gapped bilayer graphene
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Jesús Arturo Sánchez-Sánchez, Thomas Stegmann
We investigate electronic transport in gapped bilayer graphene (gBLG) devices. For certain edge terminations -typically a combination of zigzag, armchair, and bearded types - we observe edge state conduction within the band gap, which is opened by a potential bias between the two layers. The edge states can generate a non-local resistance, in line with recent experiments [1]. Band structure calculations of gBLG nanoribbons corroborate the existence of the edge states, whose edge localization can be switched by tuning the electron energy. Their existence strongly depends on the edge termination and does not originate from a topological bulk-boundary correspondence.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 7 figures
Non-uniform Thermal Conductivity in Nanoscale Multiple Hotspot Systems
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Yu He, Zhihao Zhou, Lina Yang, Nuo Yang
Understanding nanoscale hotspot thermal transport is crucial in electronic devices. Contrary to common perception, recent experiments show that closely spaced nanoscale multiple hotspots can enhance heat dissipation. Here, the thermal transport in nanoscale multiple hotspot systems is investigated by solving the phonon Boltzmann transport equation. The local thermal conductivity is proposed to describe the non-uniform spatial distribution of heat transport capability in nanoscale multiple hotspot systems. The maximum value exceeds the uniform heating case by up to 27%, which is attributed to the spatially varying fraction of unscattered phonons emitted from hotspots. Moreover, the effects and mechanisms of hotspot spacing on thermal transport are investigated, showing that reducing the hotspot spacing can enhance the heat flux by up to 40%. This work challenges the conventional view that thermal transport capability is spatially uniform throughout the system and provides fundamental insights for thermal management in high-power-density integrated circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 4 figures
Relation between extensional viscosity and polymer conformation in dilute polymer solutions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Yusuke Koide, Takato Ishida, Takashi Uneyama, Yuichi Masubuchi
We investigate extensional viscosity and polymer conformation in dilute polymer solutions under uniaxial extensional flow using dissipative particle dynamics simulations. At high extension rates, polymers are significantly stretched by extensional flows, and the extensional viscosity growth function exhibits strain hardening. To reveal their quantitative relation, we adopt an analysis method based on the Rouse-type model. We demonstrate that the extensional viscosity growth function is determined by the instantaneous gyration radii in the parallel and perpendicular directions to the extensional direction and their time derivatives. Our approach also provides a unified description of the steady-state extensional viscosity of dilute polymer solutions for various chain lengths and concentrations in terms of the polymer gyration radius.
Soft Condensed Matter (cond-mat.soft), Fluid Dynamics (physics.flu-dyn)
Local Geometric and Transport Properties of Networks that are Generated from Hyperuniform Point Patterns
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-11-27 20:00 EST
James V. Raj, Xiaohan Sun, Charles Emmett Maher, Katherine A. Newhall, Mason A. Porter
Hyperuniformity, which is a type of long-range order that is characterized by the suppression of long-range density fluctuations in comparison to the fluctuations in standard disordered systems, has emerged as a powerful concept to aid in the understanding of diverse natural and engineered phenomena. In the present paper, we harness hyperuniform point patterns to generate a class of disordered, spatially embedded networks that are distinct from both perfectly ordered lattices and uniformly random geometric graphs. We refer to these networks as \emph{hyperuniform-point-pattern-induced (HuPPI) networks}, and we compare them to their counterpart \emph{Poisson-point-pattern-induced (PoPPI) networks}. By computing the local geometric and transport properties of HuPPI networks, we demonstrate how hyperuniformity imparts advantages in both transport efficiency and robustness. Specifically, we show that HuPPI networks have systematically smaller total effective resistances, slightly faster random-walk mixing times, and fewer extreme-curvature edges than PoPPI networks. Counterintuitively, we also find that HuPPI networks simultaneously have more negative mean Ollivier–Ricci curvatures and smaller global resistances than PoPPI networks, indicating that edges with moderately negative curvatures need not create severe bottlenecks to transport. We also demonstrate that the network-generation method strongly influences these properties and in particular that it often overshadows differences that arise from underlying point patterns. These results collectively demonstrate potential advantages of hyperuniformity in network design and motivate further theoretical and experimental exploration of HuPPI networks.
Disordered Systems and Neural Networks (cond-mat.dis-nn)
13 pages; 8 figures, lots of ORCs; abstract on arXiv page shortened slightly due to maximum length requirement
Quantum Hard Spheres with Affine Quantization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
We study a fluid of quantum hard-spheres treated with affine-quantization. Assuming that the fluid obeys to Bose-Einstein statistics we solve for its thermodynamic properties using the path integral Monte Carlo method.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
7 pages, 2 figures, 1 table
From Static Pathways to Dynamic Mechanisms: A Committor-Based Data-Driven Approach to Chemical Reactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Radu A. Talmazan, Christophe Chipot
As computational chemistry methods evolve, dynamic effects have been increasingly recognized to govern chemical reaction pathways in both organic and inorganic systems. Here, we introduce a committor-based workflow that integrates a path-committor-consistent artificial neural network (PCCANN) with an iteratively trained hybrid-DFT-level message passing atomic convolutional encoder (MACE) potential. Beginning with a static nudged elastic band path, PCCANN extracts a committor-consistent string to represent the reactive ensemble. We illustrate the power of this methodology through two representative applications. First, we investigate an SNAr reaction using MACE trained at hybrid DFT level with implicit solvent. The mechanism is found to be concerted, and the dynamic approach reveals a lower barrier than static treatments. Second, we apply the same protocol to the isomerization of protonated isobutanol to protonated 2-butanol, yielding a quantitatively accurate free-energy landscape. We uncover three competing channels: the established concerted mechanism and two asynchronous stepwise routes mediated by water and methyl transfer, all with comparable activation barriers. Notably, the stepwise pathways traverse metastable intermediates that, to the best of our knowledge, have not been described in prior mechanistic studies. Calculated barrier heights and intermediate stabilities are in close agreement with high-level DFT benchmarks, demonstrating the framework’s accuracy. Together, these studies highlight mechanistic diversity across distinct systems and establish the synergistic PCCANN-MACE protocol as a proof-of-concept approach for committor-based discovery of complex reaction dynamics.
Statistical Mechanics (cond-mat.stat-mech)
Accelerated Discovery of Crystalline Materials with Record Ultralow Lattice Thermal Conductivity via a Universal Descriptor
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Xingchen Shen, Jiongzhi Zheng, Michael Marek Koza, Petr Levinsky, Jiri Hejtmanek, Philippe Boullay, Bernard Raveau, Jinghui Wang, Jun Li, Pierric Lemoine, Christophe Candolfi, Emmanuel Guilmeau
Ultralow glass-like lattice thermal conductivity in crystalline materials is crucial for enhancing energy conversion efficiency in thermoelectrics and thermal insulators. We introduce a universal descriptor for thermal conductivity that relies only on the atomic number in the primitive cell and the sound velocity, enabling fast and scalable materials screening. Coupled with high-throughput workflows and universal machine learning potentials, we identify the candidate materials with ultralow thermal conductivity from over 25, 000 materials. We further validate this approach by experimentally confirming record-low thermal conductivity values of 0.15-0.16 W/m/K from 170 to 400 K in the halide metal CsAg2I3. Combining inelastic neutron scattering with first-principles calculations, we attribute the ultralow thermal conductivity to the intrinsically small sound velocity, strong anharmonicity, and structural complexity. Our work illustrates how a universal descriptor, combined with high-throughput screening, machine-learning potential and experiment, enables the efficient discovery of materials with ultralow thermal conductivity.
Materials Science (cond-mat.mtrl-sci)
Giant critical current peak induced by pressure in kagome superconductor RbV${3}$Sb${5}$
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-27 20:00 EST
Lingfei Wang, Wenyan Wang, Tsz Fung Poon, Zheyu Wang, Chun Wai Tsang, Xinyou Liu, Shanmin Wang, Kwing To Lai, Wei Zhang, Jeffery L. Tallon, Youichi Yamakawa, Hiroshi Kontani, Rina Tazai, Swee K. Goh
Superconductivity can coexist or compete with other orders such as magnetism or density waves. Optimizing superconductivity requires identifying competing orders that may disrupt Cooper pair coherence. Here, we use the self-field critical current ($ I_{\rm c,sf}$ ) to probe pressure-tuned superconductivity in the kagome superconductor RbV$ 3$ Sb$ 5$ . As pressure destabilizes the charge-density wave (CDW) state, $ I{\rm c,sf}$ drastically enhances, peaking near the critical pressure where the CDW state is completely suppressed at zero temperature. Surprisingly, a weaker $ I{\rm c,sf}$ peak emerges within the CDW phase. Near the pressure of the weaker peak, the superconducting phase transition temperature shifts from an increasing trend with pressure to a near plateau. Our analysis suggests the possibility of a sudden change in the CDW pattern or a Lifshitz transition, highlighting the need for microscopic examinations of the CDW state for understanding the pressure evolution of superconductivity in RbV$ _3$ Sb$ _5$ .
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
9 pages, 5 figures
Lattice-to-total thermal conductivity ratio: a phonon-glass electron-crystal descriptor for data-driven thermoelectric design
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Yifan Sun, Zhi Li, Tetsuya Imamura, Yuji Ohishi, Chris Wolverton, Ken Kurosaki
Thermoelectrics (TEs) are promising candidates for energy harvesting with performance quantified by figure of merit, $ ZT$ . To accelerate the discovery of high-$ ZT$ materials, efforts have focused on identifying compounds with low thermal conductivity $ \kappa$ . Using a curated dataset of 71,913 entries, we show that high-$ ZT$ materials reside not only in the low-$ \kappa$ regime but also cluster near a lattice-to-total thermal conductivity ratio ($ \kappa_\mathrm{L}/\kappa$ ) of approximately 0.5, consistent with the phonon-glass electron-crystal design concept. Building on this insight, we construct a framework consisting of two machine learning models for the lattice and electronic components of thermal conductivity that jointly provide both $ \kappa$ and $ \kappa_\mathrm{L}/\kappa$ for screening and guiding the optimization of TE materials. Among 104,567 compounds screened, our models identify 2,522 ultralow-$ \kappa$ candidates. Follow-up case studies demonstrate that this framework can reliably provide optimization strategies by suggesting new dopants and alloys that shift pristine materials toward the $ \kappa_\mathrm{L}/\kappa$ approaching 0.5 regime. Ultimately, by integrating rapid screening with PGEC-guided optimization, our data-driven framework effectively bridges the critical gap between materials discovery and performance enhancement.
Materials Science (cond-mat.mtrl-sci), Machine Learning (cs.LG)
15 pages, 7 figures
Nucleation and wetting transitions in three-component Bose-Einstein condensates in Gross-Pitaevskii theory: exact results
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-27 20:00 EST
Jonas Berx, Nguyen Van Thu, Joseph O. Indekeu
Nucleation and wetting transitions are studied in a three-component Bose-Einstein condensate mixture within Gross-Pitaevskii theory. For special cases of intermediate segregation between components 1 and 2, the nucleation phase transition of a surfactant film of component 3 is obtained by exact solution. Additional exact results for the nucleation transition are derived in the limit of strong segregation between components 1 and 2. In this limit the exact first-order wetting phase boundary is obtained using analytical and numerical methods, and is contrasted with the exact nucleation and wetting phase boundary derived previously for a two-component Bose-Einstein condensate mixture at a hard optical wall. Exact results for the three-component mixture are compared with results from the double-parabola approximation used in an earlier work.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
24 pages, 9 figures
Mechanisms of Resistive Switching in 2D Monolayer and Multilayer Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
M. Kaniselvan, Y. R. Jeon, M. Mladenović, M. Luisier, D. Akinwande
The power and energy consumption of resistive switching devices can be lowered by reducing their active layer dimensions. Efforts to push this low-energy switching property to its limits have led to the investigation of active regions made with two-dimensional layered materials (2DLM). Despite their small dimensions, 2DLM exhibit a rich variety of switching mechanisms, each involving different types of atomic structure reconfigurations. In this review, we highlight and classify the mechanisms of resistive switching in mono and bulk 2DLM, with a subsequent focus on those occurring in a monolayer and/or localized to point defects in the crystalline sheet. We discuss the complex energetics involved in these fundamentally defect-assisted processes, including the co-existence of multiple mechanisms and influence of the contacts used. Examining the highly localized ‘atomristor’-type switching, we provide insights into the atomic motions and electronic transport across the metal-2D interfaces underlying their operation. Finally, we present the progress and our perspective on the challenges associated with the development of 2D resistive switching devices. Promising application areas and material systems are identified and suggested for further research.
Materials Science (cond-mat.mtrl-sci)
Coupled Structural and Electronic Requirements in Alpha-FASnI3 Imposed by the Sn(II) Lone Pair
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Mridhula Venkatanarayanan, Vladislav Slama, Madhubanti Mukherjee, Andrea Vezzosi, Ursula Rothlisberger, Virginia Carnevali
Alpha-Formamidinium-tin-iodide (alpha-FASnI3) is a leading candidate for lead-free photovoltaic applications, adopting a nearly cubic structure at room temperature, but its stability remains limited by oxidation-driven degradation. Reliable first-principles modelling of the photovoltaic alpha-phase is further complicated by inconsistent structural models and levels of theory in the literature. Here, we identify the structural and electronic requirements needed for a physically sound description of alpha-FASnI3, whose behaviour is governed by a pseudo-Jahn-Teller (PJT) instability arising from the stereochemically active Sn(II) lone pair.
Using 0 K relaxations, cross-code hybrid-functional benchmarks, and finite-temperature ab initio molecular dynamics, we show that a 4x4x4 supercell with randomly oriented FA+ cations is the smallest model that removes macroscopic dipoles, preserves cubic symmetry, recovers local octahedral tilts, and captures the characteristic PJT-driven Sn off-centering. Accurate band edges and a reliable band gap require a PBE0-level hybrid functional with spin-orbit coupling to treat Sn relativistic effects, together with nonlocal dispersion (rVV10) to capture the enhanced Sn-I covalency. Finite-temperature simulations reveal that Sn off-centering remains local, <111>-oriented, and robust against thermal fluctuations, and that reproducing the experimental 300 K band gap requires a 6x6x6 supercell. These results define the essential ingredients for reliable modelling of alpha-FASnI3 and provide a rigorous foundation for studying lone-pair-driven physics in tin halide perovskites.
Materials Science (cond-mat.mtrl-sci)
30 pages (Supplementary Information (SI) included), 2 figures, 6 tables (SI), 4 tables (main)
Active Learning Driven Materials Discovery for Low Thermal Conductivity Rare-Earth Pyrochlore for Thermal Barrier Coatings
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Amiya Chowdhury, Acacio Rincon Romero, Grazziela Figueredo, Tanvir Hussain
High-Entropy/multicomponent rare-earth oxides (HECs and MCCs) show promise as alternative materials for thermal barrier coatings (TBC) with the ability to tailor properties based on the combination of rare-earth elements present. By enabling the substitution of scarce or supply-risk rare-earths with more readily available alternatives while maintaining comparable material performance, HECs and MCCs offer a valuable path towards alternative TBC material design. However, navigating this search space of compositionally complex materials is both time and resource intensive. In this study, an active learning (AL) framework was employed to identify HEC/MCC materials with a pyrochlore structure, with acceptable thermal conductivity (TC) for TBC applications. The AL framework was applied through a Bayesian optimisation (BO) strategy, coupled with a random forest surrogate model. TC was selected as the optimisation criterion as that is the most basic requirement of TBC materials. Over two iterations of the AL cycle, four compositions were generated and synthesized in the lab for experimental evaluation. The first iteration yielded two single-phase pyrochlores, $ (La_{0.29}Nd_{0.36}Gd_{0.36})2Zr_2O_7$ and $ (La{0.333}Nd_{0.26}Gd_{0.15}Ho_{0.15}Yb_{0.111})_2Zr_2O_7$ , with measured thermal conductivities of 2.03 and 1.90 $ W/mK$ , respectively. The surrogate model predicted a TC of 2.009 $ W/mK$ for both compositions, demonstrating it’s accuracy for completely new compositions. The second iteration compositions showed dual-phase when synthesized, highlighting the need to take into account phase formation in the AL framework.
Materials Science (cond-mat.mtrl-sci)
Discovery and recovery of crystalline materials with property-conditioned transformers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Cyprien Bone, Matthew Walker, Kuangdai Leng, Luis M. Antunes, Ricardo Grau-Crespo, Amil Aligayev, Javier Dominguez, Keith T. Butler
Generative models have recently shown great promise for accelerating the design and discovery of new functional materials. Conditional generation enhances this capacity by allowing inverse design, where specific desired properties can be requested during the generation process. However, conditioning of transformer-based approaches, in particular, is constrained by discrete tokenisation schemes and the risk of catastrophic forgetting during fine-tuning. This work introduces CrystaLLM-{\pi} (property injection), a conditional autoregressive framework that integrates continuous property representations directly into the transformer’s attention mechanism. Two architectures, Property-Key-Value (PKV) Prefix attention and PKV Residual attention, are presented. These methods bypass inefficient sequence-level tokenisation and preserve foundational knowledge from unsupervised pre-training on Crystallographic Information Files (CIFs) as textual input. We establish the efficacy of these mechanisms through systematic robustness studies and evaluate the framework’s versatility across two distinct tasks. First, for structure recovery, the model processes high-dimensional, heterogeneous X-ray diffraction patterns, achieving structural accuracy competitive with specialised models and demonstrating applications to experimental structure recovery and polymorph differentiation. Second, for materials discovery, the model is fine-tuned on a specialised photovoltaic dataset to generate novel, stable candidates validated by Density Functional Theory (DFT). It implicitly learns to target optimal band gap regions for high photovoltaic efficiency, demonstrating a capability to map complex structure-property relationships. CrystaLLM-{\pi} provides a unified, flexible, and computationally efficient framework for inverse materials design.
Materials Science (cond-mat.mtrl-sci), Disordered Systems and Neural Networks (cond-mat.dis-nn)
Unveiling Micrometer-Range Spin-Wave Transport in Artificial Spin Ice
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Syamlal Sankaran Kunnath, Mateusz Zelent, Pawel Gruszecki, Maciej Krawczyk
Artificial spin ice (ASI) systems exhibit fascinating phenomena, such as frustration and the formation of magnetic monopole states, and Dirac strings. However, exploring the wave phenomena in these systems is elusive due to the weak dipolar coupling that governs their interactions. In this study, we demonstrate coherent spin-wave propagation in an hybrid ASI system, which is based on a multilayered ferromagnetic thin film with perpendicular magnetic anisotropy and in-plane magnetized nanoelements embedded within it. We show that this system enables spin-wave transmission over a one-micrometer distance via exchange-mediated coupling between subsystems and evanescent spin-wave tunneling through the out-of-plane magnetized parts. This system overcomes the limitations of purely dipolar interactions in standard ASIs while preserving their fundamental properties. Thus, it provides a platform for studying spin-wave phenomena in frustrated ASI systems and paves the way for exploiting them in analog signal processing with spin waves.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages main paper paper text and 4 main figures; 6 pages supporting information text and 8 supporting figures
Stabilization of Tetragonal Phase and Aluminum-Doping Effect in a Bilayer Nickelate
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-27 20:00 EST
Jia-Yi Lu, Yi-Qiang Lin, Kai-Xin Ye, Xin-Yu Zhao, Jia-Xin Li, Ya-Nan Zhang, Hao Li, Bai-Jiang Lv, Hui-Qiu Yuan, Guang-Han Cao
Recent studies suggest that the tetragonal phase of the Ruddlesden-Popper (RP) bilayer nickelate, La$ _3$ Ni$ _2$ O$ _7$ or La$ _2$ PrNi$ _2$ O$ _7$ , which is stabilized under high pressures, is responsible for high-temperature superconductivity (HTSC). In this context, realization of the tetragonal phase at ambient pressure could be a rational step to achieve the goal of ambient-pressure HTSC in the nickelate system. By employing the concept of Goldschmidt tolerance factor, we succeed in stabilizing the tetragonal phase by aluminum doping together with post annealing under moderately high oxygen pressure. X-ray and neutron diffractions verify the tetragonal $ I4/mmm$ structure for the post-annealed samples La$ _3$ Ni$ _{2-x}$ Al$ _x$ O$ _{7-\delta}$ (0.3 $ \leq x \leq$ 0.5). The Al-doped samples, including the tetragonal ones, show semiconducting properties, carry localized magnetic moments, and exhibit spin-glass-like behaviors at low temperatures, all of which can be explained in terms of charge carrier localization. Furthermore, high-pressure resistance measurements on post-annealed samples reveal that even a low Al doping ($ x$ = 0.05) suppresses superconductivity almost completely. This work gives information about the effect of nonmagnetic impurity on metallicity as well as superconductivity in bilayer nickelates, which would contribute to understanding the superconducting mechanism in RP nickelates.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
13 pages, 6+8 figures, 1+2 tables
Helical Quasiperiodic Chains with Engineered Dissipation: Liouvillian Rapidity Diagnostics of Transport and Localization
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
We study relaxation spectra of a quadratic spinless–fermion helical chain with an Aubry–Andre–type quasiperiodic potential and a single N–th neighbor (helical) hopping. Dissipation and pumping are introduced via local linear Lindblad jump operators and treated exactly using the third–quantization / Majorana covariance formalism. Focusing on periodic boundary conditions (to avoid edge artefacts) we compute the Liouvillian rapidities and their smallest nonzero real part (the rapidity gap) for several spatial dissipation patterns: uniform (all), single–site (one–site) and two–site (two–site) placement, plus pairwise gain/loss on helical partner sites. We show that uniform dissipation yields large, weakly lambda–dependent gaps, while sparse local dissipation produces gaps that shrink rapidly as the quasiperiodic potential lambda induces localization. Increasing t_N enhances relaxation by improving mode overlap with dissipative channels. Finite–size scaling, rapidity level statistics (Poisson vs Wigner–Dyson), and spatial profiles of slow modes provide a consistent picture linking Liouvillian spectral structure to transport and localization. Our results highlight Liouvillian rapidities as compact, experimentally relevant diagnostics of relaxation and sensitivity in engineered open quantum lattices.
Strongly Correlated Electrons (cond-mat.str-el)
Spatiotemporal Control of Charge +1 Topological Defects in Polar Active Matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Birte C. Geerds, Abhinav Singh, Mathieu Dedenon, Daniel J. G. Pearce, Frank Jülicher, Ivo F. Sbalzarini, Karsten Kruse
Topological defects are a conspicuous feature of active liquid crystals that have been associated with important morphogenetic transitions in organismal development. Robust development thus requires a tight control of the motion and placement of topological defects. In this manuscript, we study a mechanism to control +1 topological defects in an active polar fluid confined to a disk. If activity is localized in an annulus within the disk, the defect moves on a circular trajectory around the center of the disk. Using an ansatz for the polar field, we determine the dependence of the angular speed and the circle radius on the boundary orientation of the polar field and the active annulus. Using a proportional integral controller, we guide the defect along complex trajectories by changing the active annulus size and the boundary orientation.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
6 pages, 4 figures
Large longitudinal and anomalous transverse Magneto-thermoelectric effect in kagome antiferromagnet FeGe
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Jiajun Ma, Rong Chen, Yazhou Li, Chenfei Shi, Yantao Cao, YuWei Zhang, Jiaxing Liao, Yunfei Han, Guangxi Wen, Jialu Wang, Hanjie Guo, Jianhui Dai, Chenguang Fu, Jin-Ke Bao, Yan Sun, Zhu-An Xu, Yuke Li
Topological Kagome magnets, characterized by nontrivial electronic band structures featuring flat band, Dirac cone and van Hove singularities, provide a new avenue for the realization of thermoelectric devices. Unlike the conventional longitudinal Seebeck effect, transverse thermoelectric (TE) effects like the Nernst effect have attracted growing interest due to their unique transverse geometry and potential advantages. Here, we report the observation of a significant transverse thermoelectric conductivity alpha A_zx of 15 A K-1m-1 at low temperatures, together with a pronounced anomalous Nernst effect in the Kagome antiferromagnet FeGe, which exhibits a charge density wave inside the antiferromagnetic (AFM) state. This value is the highest record among known AFM materials. Furthermore, the thermopower at 14 T increases by 102-104% around the canted-AFM (CAFM) transition temperature, Tcant, comparable to that of the well-known AFM thermoelectric materials. These effects are attributed to large Berry curvature arising from the non-collinear spin texture in FeGe, highlighting its potential for enhancing thermoelectric performance and its candidacy for magneto-TE applications in Kagome antiferromagnetic materials.
Materials Science (cond-mat.mtrl-sci)
16 pages, 4 figures
The 2/3 Rule of Glass Physics Implies Universalities in Crystal Melting
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Peter Lunkenheimer, Konrad Samwer, Alois Loidl
Since more than 100 years, melting is thought to be governed by the Lindemann criterion. It assumes that a crystal melts when, upon heating, the growing atomic vibration amplitudes become sufficiently large to destabilize its crystalline lattice. However, it is unclear why the viscosities eta or the related relaxation times tau of the resulting liquids, measured directly at the melting point Tm, differ by up to nine decades, depending on the material. Based on the empirical rule that the ratio of the glass-transition temperature and Tm is about 2/3, here we show that this strong variation is due to differences in the liquid’s fragilities, a property associated with pronounced non-Arrhenius behavior and often ascribed to cooperative motions. We propose that, without cooperativity, all crystals would melt into liquids with a universal viscosity value and relaxation time. Hence, the real melting point is only partly determined by the Lindemann criterion and strongly enhanced by the cooperativity of the resulting liquid. Our findings are corroborated by the determination of the idealized, fragility-free melting temperatures, and of the corresponding eta and tau values for various example materials.
Soft Condensed Matter (cond-mat.soft), Disordered Systems and Neural Networks (cond-mat.dis-nn), Other Condensed Matter (cond-mat.other)
9 pages, 4 figures + Supplemental Material
Kibble-Zurek Meets Tricriticality: Breakdown of Adiabatic-Impulse and New Scaling Forms
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
The Kibble-Zurek effect is studied around a tricritical point, where the adiabatic-impulse scenario breaks down. Several new scaling forms are also proposed.
Statistical Mechanics (cond-mat.stat-mech), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
3 pages; invited Research Highlight article for Chin. Phys. Lett., recommending 2505.12595
Chin. Phys. Lett. 43, 010001 (2026)
Torsion-induced Dzyaloshinskii-Moriya interaction in helical magnets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
It has been shown that in magnets possessing an inversion center in the absence of deformations, a torsion-induced Dzyaloshinsky-Moriya interaction (tiDMI) can arise. A microscopic mechanism for this interaction is described, involving the transfer of angular momentum to the lattice upon electron reflection from the magnet’s boundary. An estimate of the tiDMI constant is provided. It is demonstrated that tiDMI can lift the chiral degeneracy in helimagnets, and a way for experimentally observing this effect is proposed.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Revealing Fast Ionic Conduction in Solid Electrolytes through Machine Learning Accelerated Raman Calculations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Manuel Grumet, Takeru Miyagawa, Olivier Pittet, Paolo Pegolo, Karin S. Thalmann, Waldemar Kaiser, David A. Egger
Fast ionic conduction is a defining property of solid electrolytes for all-solid-state batteries. Previous studies have suggested that liquid-like cation motion associated with fast ionic transport can disrupt crystalline symmetry, thereby lifting Raman selection rules. Here, we exploit the resulting low-frequency, diffusive Raman scattering as a spectral signature of fast ionic conduction and develop a machine learning-accelerated computational pipeline to identify promising solid electrolytes based on this feature. By overcoming the steep computational barriers to calculating Raman spectra of strongly disordered materials at finite temperatures, we achieve near-ab initio accuracy and demonstrate the predictive power of our approach for sodium-ion conductors, revealing clear Raman signatures of liquid-like ion conduction. This work highlights how machine learning can bridge atomistic simulations and experimental observables, enabling data-efficient discovery of fast-ion conductors.
Materials Science (cond-mat.mtrl-sci)
Controlled nucleation in methylamine-treated perovskite films by artificial seeding and phase-field simulations
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Emilia R. Schütz, Martin Majewski, Olivier J.J. Ronsin, Jens Harting, Lukas Schmidt-Mende
Large perovskite crystals with reduced defect density enable superior charge transport and stability. Therefore, controlling their nucleation and growth is key to advancing high-performance optoelectronic devices based on perovskite semiconductors. Millimeter-scale perovskite crystals can be synthesized as a continuous film through methylamine treatment, with nucleation sites directed by pre-patterned seeds. Nonetheless, certain configurations may lead to unwanted parasitic nucleation. To predict and mitigate this effect, we employ phase-field simulations alongside an analytical model. Their predictive capability is demonstrated across three distinct material-substrate systems, enabling precise control over nucleation and subsequent crystal growth. Notably, the only material-specific input required is the nucleation density (i.e., the number of crystals nucleated per unit area on an unpatterned substrate). This generality makes the models broadly applicable to diverse material systems for achieving controlled two-dimensional crystallization for improved optoelectronic device performance.
Materials Science (cond-mat.mtrl-sci)
Lattice-Distortion-Mediated Proton Pairing and Trapping in Solid State Oxides
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Hang Ma, Jiajun Linghu, Nannan Han, Ying Liang, Yiyang Sun, Tianxing Ma, Zhi-Peng Li
Experiments have evidenced proton pairing in Y-doped BaZrO3. However, the nature of proton pairing and its impact on conduction remain insufficiently understood theoretically. Here, through quantitative computational analysis of proton-proton interactions in Y-doped BaZrO3, we identify lattice-distortion-mediated elastic interaction as the key factor determining whether two protons form a stable pair or exhibit net repulsion. When a proton resides at an inward-bending distortion site induced by another proton, the resulting net repulsive interaction leads to an unstable configuration. In contrast, the proton tends to be trapped at a nearby outward-bending site that favors the formation of a stable proton pair. Moreover, the site where the two protons form the lowest-energy configuration also corresponds to a proton trapping site. By calculating the long-range diffusion pathways accessible to protons under different local environments in both single- and two-proton cases, we find that the range of rate-limiting barriers is 0.24-0.45 eV for two-proton conduction and 0.19-0.39 eV for single-proton conduction. The higher and more experimentally consistent barriers in the two-proton pathways indicate that the proton trapping effect induced by pairing hinders proton conduction. Our study elucidates the multi-proton diffusion mechanism, providing a theoretical foundation for the experimental design of electrolytes with enhanced proton conductivity.
Materials Science (cond-mat.mtrl-sci)
Size optimization for observeing Majorana fermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Guo-Jian Qiao, Zhi-Lei Zhang, Xin Yue, C. P. Sun
Majorana fermions (zero modes) are predicted to emerge in nanowire-superconductor heterostructures. This theoretical prediction typically relies on an oversimplified model, where both the nanowire and the superconductor are idealized as one-dimensional systems. In reality, heterostructures have finite sizes that deviate from this idealization-and as a result, smoking-gun evidence confirming the existence of these zero modes remains elusive. Here, we investigate the finite-size effects of both the nanowire and the superconductor, and optimize their sizes to ensure that only one Majorana fermion exists at each end of the heterostructure. It is discovered that the optimal transverse sizes of the nanowire are less than 100nm in width and approximately 1nm in thickness. For the superconductor layer, its optimal thickness (a key aspect of its size) must exceed its coherence length. We also present the optimal sizes of the two types of materials used in the experiment in a quantitative manner. Notably, the identified optimal thickness of the superconductor (Al films, $ \sim$ 1000nm)–a critical size parameter–is two orders of magnitude larger than the thickness of Al films currently utilized in experimental devices (e.g., InSb-Al and InAs-Al heterostructures). Our findings could explain why Majorana fermions have not been observed in current experiments, and offer guidance for the size selection of heterostructures to implement Majorana fermions in future studies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
12 pages, 1 table, 2 figures
Dynamics of a tracer trapped in a correlated medium in the presence of a wall
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Marcin Piotr Pruszczyk, Andrea Gambassi
We describe the random motion of a particle immersed in a thermally fluctuating medium and harmonically trapped at a certain distance from a wall. The medium, modeled by a Gaussian field with a tunable correlation length $ \xi$ , is linearly coupled to the particle and evolves according to dissipative relaxational dynamics. Dirichlet boundary conditions imposed on the field at the wall give rise to a repulsive fluctuation-induced force acting on the particle, causing a shift in its average position and a renormalization of the strength of the harmonic trap. We describe the effective overdamped dynamics of the particle, which features a nonlinear memory term depending on the wall-particle separation. We show that the two-time correlation function of the particle position features a memory-induced term that depends on the distance of the particle from the wall. At the critical point, this term decays algebraically upon increasing time and it displays a crossover from the behavior observed in the bulk to that corresponding to having the particle at the wall.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Antiferromagnetism and Kekulé valence bond order in the honeycomb optical Su-Schrieffer-Heeger-Hubbard model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Sohan Malkaruge Costa, Benjamin Cohen-Stead, Steven Johnston
The precise role of e-ph coupling in graphene and related materials on a honeycomb lattice is not yet fully understood, despite extensive research on these systems. Here, we perform sign-problem-free determinant quantum Monte Carlo (DQMC) simulations of the optical Su-Schrieffer-Heeger (oSSH)-Hubbard model on the honeycomb lattice, focusing on the parameters relevant to graphene. Performing finite-size scaling analyzes, we obtain the model’s ground state phase diagram, which includes the semi-metal (SM), Kekulé Valence Bond Solid (KVBS), and anti-ferromagnetic (AFM) phases, as well as indications of a small KVBS/AFM coexistence region. We find that a weak to moderate Hubbard repulsion, tuned toward the SM-AFM critical value in the pure honeycomb Hubbard model, enhances KVBS correlations and can even stabilize the KVBS phase. Estimating the effective parameters for graphene places it in the SM region of the phase diagram, but near the SM-KVBS phase boundary. Notably, we predict that increasing either the on-site Hubbard repulsion or the e-ph coupling strength drives graphene toward the KVBS phase rather than the AFM phase, highlighting a synergistic effect that can be exploited to further control the remarkable properties of graphene and related materials.
Strongly Correlated Electrons (cond-mat.str-el)
contain 4 figures
Dynamics of interacting bosons in a two-leg ring ladder with artificial magnetic flux and ac-driven modulations
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-11-27 20:00 EST
We investigate the nonequilibrium dynamics of interacting bosons in a two-leg ring ladder pierced by an artificial magnetic flux, where the particles are initially localized in the central sites of both rings, and the ac-driven local energy shifts are applied to the remaining lattice sites. Within the mean-field approximation, we demonstrate the emergence of nonlinear self-trapping for strong interparticle interactions, and characterize the distinct excitation regimes in the absence of the inter-ring tunneling. The artificial magnetic flux typically introduces Peierls phase factors, which induces complex-valued hopping amplitudes and leads to directed net particle currents along the chains. By further incorporating the finite inter-ring coupling and biased intra-ring hopping, we reveal that the tuning of the drive frequency and Peierls phase allows the precise control over both the intensity and direction of particle currents, which facilitates the transition between chiral and antichiral dynamics. These findings offer insights into the coherent manipulation of matter-wave transports in closed-loop lattice configurations and the exploration of nonequilibrium synthetic quantum systems in related fields.
Quantum Gases (cond-mat.quant-gas)
8 pages, 9 figures
Enabling the bulk photovoltaic effect in centrosymmetric materials through an external electric field
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Guilherme J. Inacio, Juan José Esteve-Paredes, Maurício F. C. Martins Quintela, Wendel S. Paz, Juan José Palacios
We develop a practical approach to electrically tuning the nonlinear photoresponse of two-dimensional semiconductors by explicitly incorporating a static out-of-plane electric field into the electronic ground state prior to optical excitation, as a gate bias. The method is implemented by dressing a Wannier-interpolated Hamiltonian with the field through its position matrix elements, which allows the gate bias to modify orbital hybridization and band dispersion beyond perturbative treatments. Within the independent-particle approximation, the resulting second-order (shift) conductivity is evaluated for both centrosymmetric and non-centrosymmetric layered systems. Applied to MoS$ _2$ , the approach captures the emergence of a finite shift current in centrosymmetric bilayers and the tunability of intrinsic responses in polar structures. The shift conductivity rises linearly at small fields and saturates at higher intensities, reflecting the competition between the growing shift vector and the weakening interband coupling as resonant transitions move away from high-symmetry valleys. A Taylor expansion of the field-dressed conductivity connects this behavior to the third-order optical response, revealing a unified picture of field-induced nonlinearities. These results establish field dressing of Wannier Hamiltonians as a practical route to model and predict nonlinear photocurrents in layered materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 6 figures
Fast machine learned $α$-Fe-H interatomic potential for hydrogen embrittlement
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Eetu Makkonen, Alvaro Lopez-Cazalilla, Flyura Djurabekova
In this work, we present a machine-learned interatomic potential for the $ {\alpha}$ -Fe-H system based on the tabulated Gaussian Approximation Potential (tabGAP) formalism. Trained on a Density Functional Theory (DFT) dataset of atomic configurations, energies, forces, and virials, the potential is designed to address the issue of H-induced acceleration of mechanical failure of metals, generally known as hydrogen embrittlement (HE). The proposed potential is shown to outperform the widely used classical and machine-learned interatomic potentials in fundamental properties of the $ {\alpha}$ -Fe-H system. We show that the tabGAP model reproduces H-point defect properties, H-dislocation interaction, H-H interaction, and elastic constants with nearly DFT-level accuracy at a computational cost that is competitive with the efficient classical Embedded Atom Method (EAM) potentials. We further demonstrate the utility of the tabGAP model in molecular dynamics simulations of tensile tests of a perfect, and a $ (111)[11\bar{2}]$ -notched $ {\alpha}$ -Fe structure with and without the load of H atoms. The simulations show evidence of HE via observation of accelerated decohesion of Fe atoms at the tip of the notch, and an increase in vacancy concentration driven by H-dislocation interactions. Hence, the results of the presented simulations support the hypotheses of hydrogen-enhanced decohesion (HEDE) alongside hydrogen-enhanced strain induced vacancies (HESIV) as important mechanisms for H-induced mechanical failure of iron systems.
Materials Science (cond-mat.mtrl-sci)
Fluidization induced by Magnetic Interactions in Confined Active Matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-11-27 20:00 EST
Marco Musacchio, Markus Felber, Matteo Paoluzzi, Andrea Gnoli, Andrea Puglisi, Luca Angelani
We investigate magnetic active matter in confined geometries using both experiments with magnetic toy robots Hexbugs and simulations of elongated magnetic active Brownian particles in circular domains. Standard active particles tend to accumulate at boundaries, forming clusters even at relatively low densities. In the presence of magnetic interactions, we provide evidence for a fluidization effect that inhibits clustering and shifts its onset to higher packing fractions. Moreover, magnetic dipolar interactions give rise to novel collective behaviors, such as train-like formations, rotating pairs, and particle vortices.
Soft Condensed Matter (cond-mat.soft)
Thermodynamic response functions in a cell fluid model with Curie-Weiss interaction. I. Supercritical region
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
M.P. Kozlovskii, O.A. Dobush, R.V. Romanik, I.V. Pylyuk, M.A. Shpot
Thermodynamic response functions, including the isothermal compressibility, the thermal pressure coefficient, and the thermal expansion coefficient, isochoric and isobaric heat capacities are explicitly derived for a many-particle system interacting through a Curie-Weiss-type potential. These calculations are based on an exact equation of state previously obtained for a cell fluid model in the grand canonical ensemble. The resulting response functions are presented graphically as functions of temperature, density, and chemical potential within the supercritical region.
Statistical Mechanics (cond-mat.stat-mech)
13 pages, 8 figures
Unified interface dipole theory for Fermi level pinning effect at metal-semiconductor contacts
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Ziying Xiang, Jun-Wei Luo, Shu-Shen Li
We present a unified bond dipole theory for metal-semiconductor interfaces to explain the microscopic origin of interface dipoles and Fermi level pinning (FLP) in terms of Harrison’s bond-orbital model. By combining first-principles calculations with tight-binding analysis, we show that localized bonding between semiconductor surface dangling bonds and metal orbitals is sufficient to generate a large interface dipole and induce strong FLP, even when only a single metal monolayer is present. Within this framework, metal-induced gap states (MIGS), dangling-bond-induced surface states (DBSS), and bonding states embedded in the valence band are all understood as different outcomes of the same underlying interface bonding mechanism, rather than as independent causes of FLP. We further establish that the key parameter governing FLP strength is the density of surface dangling bonds that can form new chemical bonds with the metal, which directly controls the magnitude of the bond-induced interface dipole. This picture naturally explains the weaker pinning observed in more ionic semiconductors than in covalent ones and provides practical guidance for engineering metal-semiconductor interfaces and tuning Schottky barrier heights.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
23 pages, 8 figures
Giant enhancement of transport driven by active fluctuations: impact of inertia
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-11-27 20:00 EST
Recently, a paradoxical effect has been demonstrated in which transport of a free Brownian particle driven by active fluctuations in the form of white Poisson shot noise can be significantly enhanced when it is additionally subjected to a periodic potential. This phenomenon can emerge in an overdamped system, but it may also be inertia-induced. Here, we considerably extend previous studies and comprehensively investigate the impact of inertia on the effect of free transport enhancement observed in the overdamped system. We detect that inertia can not only induce this phenomenon, but depending on a parameter regime, it may also strengthen, weaken, or even destroy it. We exemplify these different scenarios and explore the parameter space to identify the corresponding regions where they emerge. The variance of the active fluctuations amplitude distribution is a key determinant of the inertia influence on the effect of free transport amplification. Our results are relevant not only for microscopic physical systems but also for biological ones, such as, e.g., living cells, where fluctuations generated by metabolic activities are active by default.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft)
in press in Phys. Rev. E
Charge carrier relaxation dynamics in the one-dimensional Kondo lattice model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Arturo Perez-Romero, Mica Schwarm, Fabian Heidrich-Meisner
A generic question in the field of ultrafast dynamics is concerned with the relaxation dynamics and the subsequent thermalization of optically excited charge carriers. Among several possible relaxation channels available in a solid-state system, we focus on the coupling to magnetic excitations. In this paper, we study the real-time dynamics of a paradigmatic model, the Kondo lattice model in one dimension. We conduct a comprehensive study of the relaxation processes by evaluating the spin polarization of the conduction electron, the local spin-spin correlation between localized and conduction electrons, and the electronic momentum distribution. While in the well-studied cases of one or two charge carriers in a ferromagnetic background, no thermalization occurs, we demonstrate that the stationary state is compatible with thermalization if either the electronic filling is finite or the magnetic background is in the singlet sector. Our real-time simulations using the time-dependent Lanczos method are corroborated by a direct comparison with finite-temperature expectation values and an analysis of the spectrum in terms of the gap ratio.
Strongly Correlated Electrons (cond-mat.str-el)
17 pages, and 15 figures
Symmetries of excitons
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Muralidhar Nalabothula, Davide Sangalli, Fulvio Paleari, Sven Reichardt, Ludger Wirtz
Excitons, bound electron-hole pairs, are responsible for strong optical resonances near the bandgap in low-dimensional materials and wide-bandgap insulators. Although current ab initio methods can accurately determine exciton energies and eigenstates, their symmetries have been much less explored. In this work, we employ standard group-theory methods to analyse the transformation properties of excitonic states, obtained by solving the BSE, under crystal symmetry operations. We develop an approach to assign irreducible-representation labels to excitonic states, providing a state-of-the-art framework for analysing their symmetries and selection rules (including, for example, the case of exciton-phonon coupling). Complementary to the symmetry classification, we introduce the concept of total crystal angular momentum for excitons in the presence of rotational symmetries, allowing the derivation of conservation laws. Furthermore, we demonstrate how these symmetry properties can be exploited to greatly enhance the computational efficiency of exciton calculations with the BSE. We apply our methodology to three prototypical systems to understand the role of symmetries in different contexts: (i) For LiF, we present the symmetry analysis of the entire excitonic dispersion and examine the selection rules for optical absorption. (ii) In the calculation of resonant Raman spectra of monolayer MoSe2, we demonstrate how the conservation of total crystal angular momentum governs exciton-phonon interactions, leading to the observed resonant enhancement. (iii) In bulk hBN, we analyze the role of symmetries for the coupling of finite-momentum excitons to finite-momentum phonons and their manifestation in the phonon-assisted luminescence spectra. This work establishes a general and robust framework for understanding the symmetry properties of excitons in crystals, providing a foundation for future studies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Saturation Field as a Direct Probe of Exchange and Single-Ion Anisotropies in Spin-1 Magnets
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
M. A. R. Griffith, S. Rufo, H. Caldas, F. Dinola Neto, Minos A. Neto, J. R. Viana
High magnetic fields provide a direct route to probe the anisotropies that govern spin dynamics in layered magnets. Using the SU(3) bond operator framework for spin 1 systems, we derive analytic expressions for the magnon spectrum and the critical fields delimiting the field induced ordered phase. We show that the upper critical field $ h_{c2}$ carries a simple and quantitative fingerprint of both exchange anisotropy and single ion symmetry breaking, enabling high field experiments to serve as sensitive probes of microscopic anisotropy. We further map how these anisotropies, together with interlayer coupling, control the extent and location of the magnon Bose Einstein condensation dome. Our results provide experimentally accessible criteria for identifying symmetry breaking mechanisms in real spin 1 materials.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 4 figures
Formation of Light-Emitting Defects in Ag-based Memristors
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Diana Singh, Maciej Ćwierzona, Sebastian Maćkowski, Alexandre Bouhelier
Optical memristors are innovative devices that enable the integration of electro-optical functionalities - such as light modulation, multilevel optical memory, and nonvolatile reprogramming - into neuromorphic networks. Recently, their capabilities have expanded with the development of light-emitting memristors, which operate through various emission mechanisms. One notable process involves the electroluminescence of defects generated within the switching matrix during device activation. In this study, we explore the early-stage formation and evolution of the species responsible for light emission in Ag-based in-plane memristors. Our approach combines electrical stimulation with correlated optical electroluminescence and photoluminescence measurements. The findings provide valuable insights into controlling emission processes in memristors, paving the way for their integration as essential components in neuromorphic circuits.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 6 figures. Prepared for submission
Phonon-tunable THz magnonic emission in multiferroic heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Sylvain Massabeau, Amr Abdelsamie, Florian Godel, Filip Miljevic, Noela Rezi, Pascale Gemeiner, Karim Bouzehouane, Thomas Buttiens, Sukhdeep Dhillon, Thomas Maroutian, Jean-Marie George, Henri Jaffres, Brahim Dkhil, Stephane Fusil, Vincent Garcia, Romain Lebrun
Collective excitations such as magnons and polar phonons provide natural access to the terahertz (THz) regime, but efficient generation and tunability remain elusive. Multiferroic BiFeO3 combines both orders at room temperature, offering a unique platform for narrowband THz emission. Here, we achieve efficient sub-bandgap optical rectification of coupled phonon-polaritons near 2 THz in bare epitaxial thin films. In Pt/BiFeO3 bilayers, we demonstrate that coupling the electromagnon branch with ultrafast strain waves, optically generated in Pt layers with various thicknesses, can produce tunable and narrowband emission between 0.4-0.8 THz. These results uncover the intertwined role of phonons, magnons, and magneto-acoustic dynamics in antiferromagnetic multiferroics, and establish these hybrid platforms as versatile engineered narrowband THz sources.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Unconventional orders in the maple-leaf ferro-antiferromagnetic Heisenberg model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Lasse Gresista, Dominik Kiese, Simon Trebst, Yasir Iqbal
Motivated by the search for unconventional orders in frustrated quantum magnets, we present a multi-method investigation into the nature of the quantum phase diagram of the spin-$ 1/2$ Heisenberg model on the maple-leaf lattice with three symmetry-inequivalent nearest-neighbor interactions. It has been argued that the parameter regime with antiferromagnetic couplings on hexagons $ J_h$ and ferromagnetic couplings on triangles $ J_t$ and dimer $ J_d$ bonds, is potentially host to a cornucopia of emergent phases with unconventional orders. Our analysis indeed identifies an extended region where any conventional dipolar magnetic order is absent. A hexagonal singlet state is found in the region around $ J_{d}=J_{t}=0$ , while a dimerized hexagonal singlet order of a lattice nematic character appears proximate to the phase boundary with the c$ 120^\circ$ antiferromagnetic order. Interestingly, upon traversing the bulk of the paramagnetic (PM) region, we find a variety of distinct correlation profiles, which are qualitatively different from those of the hexagonal singlet and dimerized hexagonal singlet orders but feature no appreciable spin-nematic response, while the boundary with the ferromagnetic phase shows evidence of spin-nematic order. This PM region is thus likely host to an ensemble of nonmagnetic phases which could putatively include quantum spin liquids. Our phase diagram is built from a complementary application of state-of-the-art implementations of the cluster mean-field and pseudo-fermion functional renormalization group approaches, together with an unconstrained Luttinger-Tisza treatment of the model providing insights from the semi-classical limit.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
17 pages, 10 figures
Dichroism from Thermoelectric Chiral Drives: Generalized Sum Rules for Orbital and Heat Magnetizations
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-11-27 20:00 EST
Baptiste Bermond, Lucila Peralta Gavensky, Anaïs Defossez, Nathan Goldman
We introduce a unified framework that relates orbital and heat magnetizations to experimentally accessible excitation spectra, through thermoelectric probes and generalized sum rules. By analyzing zero-temperature transport coefficients and applying Kramers-Kronig relations, we derive spectral representations of magnetization densities from thermoelectric correlation functions. Excitation rates under thermoelectric chiral drives then naturally emerge as direct probes of these Kubo-type correlators, placing orbital and heat magnetizations on equal footing with the topological Chern number. As a direct consequence of our formalism, we introduce a hierarchical construction that organizes orbital and heat magnetizations into distinct physical contributions accessible through sum rules, and also derive real-space markers of these magnetizations. From an experimental standpoint, we propose concrete implementations of thermoelectric dichroic measurements in quantum-engineered platforms based on modulated strain fields. These results establish thermoelectric dichroic measurements as a versatile route to access and disentangle fundamental ground-state properties.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
14 pages, 2 figures
Edge-Dependent Superconductivity in Twisted Bismuth Bilayers
New Submission | Superconductivity (cond-mat.supr-con) | 2025-11-27 20:00 EST
Isaías Rodríguez, Renela M. Valladares, Alexander Valladares, David Hinojosa-Romero, Flor B. Quiroga, Ariel A. Valladares
Twisted bilayers offer a compelling and, at times, confounding platform for the engineering of new twistronic materials. Whereas standard studies almost exclusively focus on the explicit enigma that is presented by twist-angles, perhaps better epitomized by the related phenomena that have been observed in twisted bilayer graphene, functional devices necessarily face a fundamental concern: boundary heterogeneity in their structures. In this study, we address this concern by strictly investigating the electronic properties of twisted bismuth bilayers at the flake’s edges and the vibrational properties of the flake. Twisted flakes exhibit continuous variations of these properties, away from the bulk, as we herein report using ab initio density functional theory, by systematically mapping the drastic evolution of band topology, electronic density of states, and possible superconductivity. Our work reveals a dramatic, non-fortuitous consequence of the structural disorder at the edges of the flakes: an enhanced electronic density of states at the Fermi level. This enhancement reaches a maximum of 10 times that of perfect-crystalline bismuth. Given that the superconducting critical temperature, Tc, is exponentially dependent on the electronic density of states at the Fermi level, this substantial structural variation immediately suggests a powerful mechanism for vastly increasing Tc. We also identify the twist-angle as a new critical parameter in designing novel engineering devices with topologically enhanced properties. Our results provide a necessary theoretical framework for interpreting new data for the upcoming generation of twistronic heterogeneous materials, and pave the way to search for atomic disordered metastable structures that could lead to enhanced superconducting transition temperatures.
Superconductivity (cond-mat.supr-con), Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph)
16 pages, 9 figures
On the generalized Keffer form of the Dzyaloshinskii constant: its consequences for the spin, momentum and polarization evolution
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-11-27 20:00 EST
Different analytical features of the Dzyaloshinskii-Moriya interaction are related to different contribution to the Dzyaloshinskii constant in the microscopic Hamiltonian. Consequences appear in the macroscopic Landau–Lifshitz–Gilbert equation. It leads to various phenomena. Three contributions to the Dzyaloshinskii constant are reviewed and combined in the generalized Keffer form of the Dzyaloshinskii constant. Macroscopic consequences of these three mechanisms are well-known, but further possible generalizations of the Keffer form of the Dzyaloshinskii constant are suggested. Consequences for the spin evolution equations, the momentum balance equations, and polarization evolution equations are considered. Some analog of the Keffer form is suggested for the exchange integral in symmetric Heisenberg Hamiltonian demonstrating the nontrivial contribution of the ligands in this regime.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
16 pages, 5 figures
Mean-field Modelling of Moiré Materials: A User’s Guide with Selected Applications to Twisted Bilayer Graphene
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-11-27 20:00 EST
Yves H. Kwan, Ziwei Wang, Glenn Wagner, Nick Bultinck, Steven H. Simon, Siddharth A. Parameswaran
We review the theoretical modelling of moiré materials, focusing on various aspects of magic-angle twisted bilayer graphene (MA-TBG) viewed through the lens of Hartree-Fock mean-field theory. We first provide an elementary introduction to the continuum modelling of moiré bandstructures, and explain how interactions are incorporated to study correlated states. We then discuss how to implement mean-field simulations of ground state structure and collective excitations in this setting. With this background established, we rationalize the power of mean-field approximations in MA-TBG, by discussing the idealized “chiral-flat” strong-coupling limit, in which ground states at electron densities commensurate with the moiré superlattice are exactly captured by mean-field ansätze. We then illustrate the phenomenological shortcomings of this limit, leading us naturally into a discussion of the intermediate-coupling incommensurate Kekulé spiral (IKS) order and its origins in ever-present heterostrain. IKS and its placement within an expanded Hartree-Fock manifold form our first “case study”. Our second case study involves time-dependence, and focuses on the collective modes of various broken-symmetry insulators in MA-TBG. As a third and final case study, we return to the strong-coupling picture, which can be stabilized by aligning MA-TBG to an hBN substrate. In this limit, we show how mean field theory can be adapted to the translationally non-invariant setting in order to quantitatively study the energetics of domain walls in orbital Chern insulating states. We close with a discussion of extensions and further applications. Used either as a standalone reference or alongside the accompanying open-source code, this review should enable readers with a basic knowledge of band theory and many-body physics to systematically build and analyze detailed models of generic moiré systems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
72 pages, 9 figures