CMP Journal 2025-08-18
Statistics
Nature Materials: 1
Nature Nanotechnology: 1
Nature Reviews Physics: 1
arXiv: 49
Nature Materials
Superconductivity in Sr-doped La3Ni2O7 thin films
Original Paper | Superconducting properties and materials | 2025-08-17 20:00 EDT
Bo Hao, Maosen Wang, Wenjie Sun, Yang Yang, Zhangwen Mao, Shengjun Yan, Haoying Sun, Hongyi Zhang, Lu Han, Zhengbin Gu, Jian Zhou, Dianxiang Ji, Yuefeng Nie
Recent studies have demonstrated ambient pressure superconductivity in compressively strained La3Ni2O7 thin films, yet the phase diagram of heterovalent doping–critical for advancing the field–remains underexplored. Here we report superconductivity in Sr2+-doped La3-xSrxNi2O7 films. The superconducting transition temperature (Tc) follows an incomplete dome-like profile, maintaining similar Tc values across a wide doping range (0 ≤ x ≤ 0.21) before diminishing near x ≈ 0.38. Optimally doped films achieve a Tc value of ~42 K, with a high critical current (Jc > 1.4 kA cm-2 at 2 K) and upper critical fields (μ0Hc,∥(0) = 83.7 T, μ0Hc,⟂(0) = 110.3 T). Scanning transmission electron microscopy reveals that oxygen vacancies predominantly occupy planar NiO2 sites–unlike apical-site vacancies in bulk samples–due to compressive strain. Additionally, the elongated out-of-plane Ni-O bonds, exceeding those in pressurized bulk samples by 4%, likely weaken the interlayer ({d}_{ {z}^{2}}) coupling and contribute to the reduced Tc in strained films.
Superconducting properties and materials, Surfaces, interfaces and thin films
Nature Nanotechnology
Acoustically activatable liposomes as a translational nanotechnology for site-targeted drug delivery and noninvasive neuromodulation
Original Paper | Drug delivery | 2025-08-17 20:00 EDT
Mahaveer P. Purohit, Brenda J. Yu, Kanchan Sinha Roy, Yun Xiang, Sedona N. Ewbank, Matine M. Azadian, Alex R. Hart, Gabriella P. B. Muwanga, Payton J. Martinez, Jeffrey B. Wang, Ali K. Taoube, Eric Markarian, Nicholas Macedo, Audrey K. Kwan, Diego Gomez Lopez, Raag D. Airan
Stimulus-responsive drug delivery nanotechnologies promise noninvasive activation of the right drug at the right place at the right time. However, these systems often incorporate non-validated pharmaceutical excipients and other features that limit their clinical translation. Here we engineer the responsiveness of liposomes to a pulsed, low-intensity ultrasound activating stimulus by incorporating a generally regarded as safe excipient that alters the acoustic properties of the liposome core medium. We show that this approach permits loading and ultrasound-induced release of four drugs in vitro. We then leverage this performance to enable drug-mediated noninvasive neuromodulation of each of the central and the peripheral nervous system in vivo. These acoustically activatable liposomes formulated with common and validated pharmaceutical excipients and production processes provide a versatile system for stimulus-responsive site-targeted drug delivery and noninvasive neuromodulation, with high clinical translation potential.
Drug delivery, Nanoparticles
Nature Reviews Physics
Point defects in metal halide perovskites
Review Paper | Semiconductors | 2025-08-17 20:00 EDT
Nuo Xu, Xinrui Qi, Zhenqiang Shen, Lianghe Hu, Jun Lv, Yufei Zhong, Bing Wang, Zhigang Zou
Halide perovskites have exceptional optoelectronic properties, including low carrier recombination rates; however, their stability remains a challenge. Point defects play a crucial role in determining their physical characteristics, as they affect carrier dynamics and serve as the initiation sites for various ion migration processes. In the past five years, advances in computational methodologies have deepened the understanding of defect behaviour in these materials. In this Review, we focus on the role of point defects in metal halide perovskites, their impact on carrier dynamics, and ion-migration-related behaviours, and we discuss new understandings of defect tolerance.
Semiconductors, Solar energy and photovoltaic technology
arXiv
Superconductivity in atom-intercalated quaternary hydrides under ambient pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-18 20:00 EDT
Bo-Wen Yao, Zhenfeng Ouyang, Xiao-Qi Han, Chang-Jiang Wu, Peng-Jie Guo, Ze-Feng Gao, Zhong-Yi Lu
Hydrogen-rich materials are the most promising candidates for high-temperature conventional superconductors under ambient pressure. Multinary hydrides have abundant structural configurations and are more promising to find high-temperature superconductors at ambient pressure, but searching for multinary materials in complex phase space is a great challenge. In this work, we used our developed AI search engine (InvDesFlow) to perform extensive investigations regarding ambient stable superconducting hydrides. Several quaternary hydrides with high superconducting temperature($ T_c$ ) are predicted. In particular, the superconducting $ T_c$ of K$ _2$ GaCuH$ _6$ and K$ _2$ LiCuH$ _6$ are calculated to be 68K and 53K under ambient pressure, respectively, which shows a significant enhancement in comparison with that of K$ _2$ CuH$ _6$ ~($ T_c$ $ \sim$ 16K). We also find that intercalating atoms could cause phonon softening and induce more phonon modes with strong electron-phonon coupling. Hence, we propose that intercalating atoms is a feasible approach in searching for superconducting quaternary hydrides.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
7 pages
Tunable optical emissions of Eu3+ ions enabled by pressure-driven phase transition in ZnO
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
C. Ianhez-Pereira, U. F. Kaneko, A. D. Rodrigues, I. S. S. de Oliveira, M. P. F. de Godoy
Controlling the optical properties of rare-earth ions in wide-bandgap semiconductors remains a major challenge in the development of next-generation photonic materials. Here, we show that external hydrostatic pressure modulates the structural characteristics of ZnO thin films and, in turn, tunes the optical emission behavior of embedded Eu3+ ions. By combining in situ synchrotron X-ray diffraction and photoluminescence spectroscopy under high-pressure conditions with first-principles calculations, we capture a pressure-induced phase transition from the hexagonal wurtzite to the cubic rocksalt structure near 10 GPa. This transformation is accompanied by complete quenching of the D0 - FJ Europium emissions near the transition threshold, followed by a partial recovery at higher pressures, likely associated with the emergence of structural disorder. Concurrently, the Stark components of the emission bands exhibit a redshift and significant broadening with increasing pressure, reflecting enhanced crystal field strength as interatomic distances decrease. Additional first-principles calculations support the observed pressure-induced shifts in the Eu-4f states and emphasize the influence of lattice symmetry on their electronic environment. These results show that hydrostatic pressure is an effective way to adjust the optical emissions of rare-earth ions by changing their symmetry and local environment, providing a basis for designing photonic devices and luminescent materials controlled by pressure.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Gapped spinful phases obtained via Gutzwiller projections of Euler states
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Thorsten B. Wahl, Lukas Devos, Robert-Jan Slager
Gutzwiller projections of non-interacting chiral topological phases are known to give rise to fractional, topologically ordered chiral phases. Here, we carry out a similar construction using two copies of non-interacting Euler insulators to produce a class of spinful interacting Euler models. To that end, we take advantage of the recently discovered exact representation of certain Euler insulators by a projected entangled pair state (PEPS) of bond dimension $ D = 2$ . The Gutzwiller projection can be implemented within the tensor network formalism, giving rise to a new PEPS of bond dimension $ D = 4$ . We, moreover, apply very recent state-of-the-art tensor network tools to evaluate these phases. In particular, we analyze its entanglement entropy scaling and find no topological correction to the area law, indicating that the state is not intrinsically topologically ordered. Its entanglement spectrum shows a clear cusp at momentum zero, similar to non-interacting Euler insulators, and the spectrum of the transfer operator indicates that the state is gapped, which could imply non-intrinsic topological features. Finally, the static structure factor displays Bragg peaks, indicating the simultaneous presence of local order.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
9 pages, 9 figures
Suppression of coherent light scattering in a three-dimensional atomic array
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
Yu-Kun Lu, Hanzhen Lin, Jiahao Lyu, Yoo Kyung Lee, Vitaly Fedoseev, Wolfgang Ketterle
Understanding how atoms collectively interact with light is not only important for fundamental science, but also crucial for designing light-matter interfaces in quantum technologies. Over the past decades, numerous studies have focused on arranging atoms in ordered arrays and using constructive (destructive) interference to enhance (suppress) the coupling to electromagnetic fields, thereby tailoring collective light-matter interactions. These studies have mainly focused on one- and two-dimensional arrays. However, only three-dimensional (3D) arrays can demonstrate destructive interference of coherent light scattering in all directions. This omnidirectional suppression of coherent light scattering in 3D atomic arrays has thus far not been experimentally demonstrated. Here, we observe a strong reduction of light scattering in a 3D atomic array prepared in the form of a Mott insulator in optical lattices. The residual light scattering is shown to be caused by the delocalization of atoms, Raman scattering, and inelastic scattering associated with saturation. We also demonstrate how light scattering can be a sensitive probe for density fluctuations in many-body states in optical lattices, enabling us to characterize the superfluid-to-Mott insulator phase transition as well as defects generated by dynamical parameter ramps. The results of our work can be used to prepare subradiant states for photon storage and probe correlations for many-body systems in optical lattices.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Quantum Physics (quant-ph)
Unconventional Phase Separation and Fractal Interfaces of Colloids in Active Liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-18 20:00 EDT
Pragya Kushwaha, Pratikshya Jena, Partha Sarathi Mondal, Sanjay Puri, Shradha Mishra, Vijayakumar Chikkadi
Phase separation driven by nonequilibrium fluctuations is a hallmark of both living and synthetic active matter. Unlike equilibrium systems, where ordered states arise from the minimization of free energy, active systems are fueled by a constant injection of energy at the microscopic scale. The emergence of ordered phases in such driven systems challenges our conventional views of domain growth and interfacial structure. In this study, we investigate the coarsening of colloidal clusters in active liquids containing E. coli. Our experiments reveal that uniform dispersions of colloids and swimmers are inherently unstable, resulting in spontaneous phase separation characterized by fractal interfaces and unconventional kinetics. The correlation function of the order parameter displays dynamical scaling, with the size of colloidal domains growing as $ t^{1/z}$ , where $ z \sim 4$ , in contrast to the well-known growth laws for thermal systems with a conserved order parameter. Furthermore, the structure factor exhibits non-Porod behavior, indicating domains with fractal interfaces. This non-Porod behavior also manifests itself as a cusp singularity in the correlation function. We elucidate our experimental findings using a scalar field theory in which the nonequilibrium fluctuations arising from swimmer activity are modeled as spatio-temporally correlated noise. This coarse-grained model, which breaks time-reversal symmetry and detailed balance, successfully reproduces key experimental observations. Furthermore, it reveals a fluctuating microphase separation, where the initial domain growth, following $ t^{1/4}$ scaling, is eventually arrested, thereby shedding new light on the microscopic origins of unconventional phase separation of colloids in active liquids.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Spontaneously Broken Non-Invertible Symmetries in Transverse-Field Ising Qudit Chains
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Kristian Tyn Kai Chung, Umberto Borla, Andriy H. Nevidomskyy, Sergej Moroz
\usepackage{iopams} Recent developments have revealed that symmetries need not form a group, but instead can be non-invertible. Here we use analytical arguments and numerical evidence to illuminate how spontaneous symmetry breaking of a non-invertible symmetry is similar yet distinct from ordinary, invertible, symmetry breaking. We consider one-dimensional chains of group-valued qudits, whose local Hilbert space is spanned by elements of a finite group $ G$ (reducing to ordinary qubits when $ G=\mathbb{Z}_2$ ). We construct Ising-type transverse-field Hamiltonians with Rep($ G$ ) symmetry whose generators multiply according to the tensor product of irreducible representations (irreps) of the group $ G$ . For non-Abelian $ G$ , the symmetry is non-invertible. In the symmetry broken phase there is one ground state per irrep on a closed chain. The symmetry breaking can be detected by local order parameters but, unlike the invertible case, different ground states have distinct entanglement patterns. We show that for each irrep of dimension greater than one the corresponding ground state exhibits string order, entanglement spectrum degeneracies, and has gapless edge modes on an open chain – features usually associated with symmetry-protected topological order. Consequently, domain wall excitations behave as one-dimensional non-Abelian anyons with non-trivial internal Hilbert spaces and fusion rules. Our work identifies properties of non-invertible symmetry breaking that existing quantum hardware can probe.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
16 pages, 3 figures
Study on fluctuations of interface-enhanced superconductivity in ultrathin FeSe/SrTiO3 by the Nernst effect
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-18 20:00 EDT
Tomoki Kobayashi, Ryo Ogawa, Atsutaka Maeda
Ultrathin FeSe films on SrTiO3 substrate show interface-enhanced superconductivity. However, how the superconductivity is established including superconducting fluctuations remains unclear. This study investigates the Nernst effect, which is sensitive to superconducting fluctuations, in ultrathin FeSe films on SrTiO3. Temperature dependence of Nernst signals in the normal state is similar to bulk FeSe, suggesting that the electrons of SrTiO3 are transferred only to a few layers near the FeSe/SrTiO3 interface. The Nernst effect caused by SC fluctuations was observed only below T ~ 1.2 Tconset within our measurement resolution, which is similar to other Fe chalcogenide systems. Our results suggest that the pseudogap in monolayer FeSe/STO possibly originates in other electronic states rather than superconductivity.
Superconductivity (cond-mat.supr-con)
8 pages, 6 figures
Chiral Phonons in Graphyne
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Subhendu Mishra, Arpan Chakraborty, Douglas S. Galvao, Pedro A. S. Autreto, Abhishek Kumar Singh
Chiral phonons, quantized lattice vibrations with circular polarization and non-zero angular momentum, offer new perspectives for phononic and quantum device engineering. Graphyne could be a promising candidate due to its unique lattice geometry, valley-structured electronic bands, and thermal transport capabilities. However, chiral phonons in graphyne remain unexplored owing to the existence of inversion ($ \mathscr{P}$ ) and time-reversal ($ \mathscr{T}$ ) symmetries. Herein, we have demonstrated the existence of chiral phonons in graphynes, achieved by breaking combined $ \mathscr{PT}$ symmetry through atomic-selective substitutional doping. We find that the B, N, dopants and ortho BN co-dopant in 6-6-12 and $ \gamma$ -graphynes induce localized structural deformations. These deformations lift phonon degeneracies away from $ \Gamma$ point and give rise to circularly polarized vibrational modes. We further established a strong correlation between chiral phonon angular momentum and electron affinity of dopants. Electron-rich dopants increase local electron density which could enable chiral phonon modes to couple more effectively with electronic environment. This in turn increases phonon angular momentum, indicating potential role of electron-phonon interactions in angular momentum modulation of chiral phonons. Our prosposed approach provides a tunable route for controlling chiral phonon behavior, paving way for development of advanced phononic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Atomic Physics (physics.atom-ph), Chemical Physics (physics.chem-ph), Quantum Physics (quant-ph)
Submitted to a ACS journal
Nonextensive Thermodynamics of the Morse Oscillator: Signature and Solid State Application
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
In this work, we present a detailed thermodynamic analysis of a bound quantum system: the Morse oscillator within the framework of Tsallis nonextensive statistics. Using the property of the bound spectrum (upper bound) of the Morse potential, limited by the bond dissociation energy, we analytically derive the generalized partition function. We present results for both the high- and low-temperature limits. We propose the effective number of accessible states as a measure of nonextensivity. The calculation shows that the nonextensive framework further restricts the number of accessible states. We also derive the generalized internal energy and entropy and examine their dependence on temperature and the nonextensivity parameter ( q ). Numerical results confirm the strong effect of nonextensive behavior in the low-temperature regime (precisely low to moderate temperature), where the ratio of generalized internal energy and internal energy calculated from the Boltzmann Gibbs (BG) formula develops a nontrivial dip structure for ( q < 1 ). Moreover, the generalized specific heat shows the Schottky-type anomaly. We extend our study by deriving the specific heat of solids with BG and Tsallis statistics using the anharmonic energy levels of the Morse oscillator. This study suggests that the Morse oscillator is a solvable and physically meaningful testing ground for exploring the thermodynamics of quantum systems driven by nonextensive statistics, with implications for the vibrational properties of the non-equilibrium molecular thermodynamics (especially diatomic molecules).
Statistical Mechanics (cond-mat.stat-mech)
23 pages, 6 figures
Circulation Statistics and Migdal Area Rule Beyond the Kibble-Zurek Mechanism in a Newborn Bose-Einstein Condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
Matteo Massaro, Seong-Ho Shinn, Mithun Thudiyangal, Adolfo del Campo
The Kibble-Zurek mechanism (KZM) predicts that a newly formed superfluid prepared by a finite-time thermal quench is populated with vortices. The universality of vortex number statistics, beyond KZM, enables the characterization of circulation statistics within any region of area $ A$ enclosed by a loop $ C$ . Migdal’s minimal area rule of classical turbulence predicts that the probability density function of circulation around a closed contour is independent of the contour’s shape. We verify the Migdal area rule for small loops with respect to the distance between the vortex and antivortex pairs and further characterize its universal breakdown for bigger loops. We further uncovered the nonequilibrium universality dictated by the KZM dynamics, which results in power-law scalings of the moments of the circulation statistics as a function of the quench time.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
5+4 pages, 4+3 figures
Exact kinetic propagators for coherent state complex Langevin simulations
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
Thomas G. Kiely, Ethan C. McGarrigle, Glenn H. Fredrickson
We introduce and benchmark an improved algorithm for complex Langevin simulations of bosonic coherent state path integrals. Our approach utilizes a Strang splitting of the imaginary-time propagator rather than the conventional linear-order Taylor expansion, allowing us to construct an action that incorporates higher-order terms at negligible computational cost. The resulting algorithm enjoys guaranteed linear stability independent of the imaginary-time discretization, enabling more resource-efficient simulations. We demonstrate this improved performance for single-species bosons and for two-component bosons with Rashba spin-orbit coupling.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech)
5 pages, 2 figures
Atomic perspective on the topological magnetism in kagome metal Co3Sn2S2
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Guowei Liu, Wei Song, Titus Neupert, M. Zahid Hasan, Hanbin Deng, Jia-Xin Yin
Topological quantum materials with kagome lattices have attracted intense interest due to their unconventional electronic structures, which exhibit nontrivial topology, anomalous magnetism, and electronic correlations. Among these, Co3Sn2S2 stands out as a prototypical kagome metal, uniquely combining intrinsic ferromagnetism with topologically nontrivial electronic states. This perspective presents a systematic overview of recent advances in studying kagome metal Co3Sn2S2 achieved through scanning tunneling microscopy. We begin by introducing different methodologies for surface identification and propose using designer layer-selective chemical markers for conclusive surface identification. We then discuss the Berry curvature induced flat band orbital magnetism and the associated unconventional Zeeman effect. Furthermore, we explore boundary states arising from Weyl topology and analyze challenges in detecting Fermi arcs via quasiparticle interference patterns and in uncovering the topological aspect of the edge states. Finally, we review recent observations of spin-orbit-coupled quantum impurity states through spin-polarized tunneling spectroscopy, as well as their connection to Weyl topology and flat band magnetism. We also provide in-depth analysis and constructive comments on the limitations of the current research approach. This review highlights the critical role of scanning tunneling microscopy in unraveling the intricate interplay between topology, magnetism, and correlations at the atomic scale, and the methodology discussed here can be applied to study other topological quantum materials in general.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
To appear in Quantum Frontiers (2025)
Electron Ptychography Images Hydrogen Atom Superlattices and 3D Inhomogeneities in Palladium Hydride Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Zixiao Shi, Qihao Li, Himani Mishra, Desheng Ma, Héctor D. Abruña, David A. Muller
When hydrogen atoms occupy interstitial sites in metal lattices, they form metal hydrides (MHx), whose structural and electronic properties can differ significantly from the host metals. Owing to the small size of hydrogen atom and its unique interactions with the host metal, MHx is of broad interest in both fundamental science and technological applications. Determining where the hydrogen is located within the MHx, and whether it orders on the partially occupied interstitial sites is crucial for predicting and understanding the resultant physical and electronic properties of the hydride. Directly imaging hydrogen within a host material remains a major challenge due to its weak interaction with X-rays and electrons in conventional imaging techniques. Here, we employ electron ptychography, a scanning transmission electron microscopy technique, to image the three-dimensional (3D) distribution of H atoms in Palladium hydrides (PdHx) nanocubes, one of the most studied and industrially relevant MHx materials. We observe an unexpected one-dimensional superlattice ordering of hydrogen within the PdHx nanocubes and 3D hydrogen clustering in localized regions within PdHx nanocubes, revealing spatial heterogeneity in metal hydride nanoparticles previously inaccessible by other methods.
Materials Science (cond-mat.mtrl-sci)
5 figures, 19 SI figures
Ferromagnetic and Spin-Glass Finite-Tempeature Order but no Antiferromagetic Order in the d=1 Ising Model with Long-Range Power-Law Interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
The d=1 Ising ferromagnet and spin glass with long-range power-law interactions J r^-a is studied for all interaction range exponents a by a renormalization-group transformation that simultaneously projects local ferromagnetism and antiferromagnetism. In the ferromagnetic case, J>0, a finite-temperature ferromagnetic phase occurs for interaction range 0.74<a<2. The second-order phase transition temperature monotonically decreases between these two limits. At a=2, the phase transition becomes first order, as predicted by rigorous results. For a>2, the phase transition temperature discontinuously drops to zero and for a>2 there is no ordered phase above zero temperature, also as predicted by rigorous results. At the other end, on approaching a=0.74 from above, namely increasing the range of the interaction, the phase transition temperature diverges to infinity, meaning that, at all non-infinite temperatures, the system is ferromagnetically ordered. Thus, the equivalent-neighbor interactions regime is entered before (a > 0) the neighbors become equivalent, namely before the interactions become equal for all separations. The critical exponents alpha,beta, gamma,delta,eta,nu are calculated, from a large recursion matrix, varying as function of a. For antiferromagnetic J<0, all triplets of spins at all ranges have competing interactions and this highly frustrated system does not have an ordered phase. In the spin-glass system, where all couplings for all separations are randomly ferromagnetic or antiferromagnetic (with probability p), a finite-temperatures spin-glass phase is obtained in the absence of antiferromagnetic phase. In the spin-glass phase, the signature chaotic behavior under scale change occurs in a richer version than previously: In the long-range interaction of this system, the interactions at every separation become chaotic, yielding a piecewise chaotic interaction function.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn)
5 pages, 4 figures
Frequency Dependence of Phonon-Induced Current Noise in ArmchairCarbon Nanotube
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Raimu Akimoto, Aina Sumiyoshi, Takahiro Yamamoto
We theoretically investigate the frequency dependence of phonon-induced current noise in armchair carbon nanotubes at room temperature. Our results reveal the emergence of multiple resonance peaks in the high-frequency regime, which cannot be accounted for by the Lorentzian lineshape expected from a Markovian process. The electron-phonon scattering processes responsible for most of these peaks are identified based on energy and momentum conservation laws and conventional selection rules. However, certain peaks cannot be fully explained within the framework of harmonic phonon scattering, suggesting the involvement of nontrivial interactions between electrons and anharmonic phonons.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
5 pages, 4 figures
Statistical Properties of Current Noise Induced by Electron-Phonon Scattering in Metallic Carbon Nanotubes
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Aina Sumiyoshi, Keisuke Ishizeki, Takahiro Yamamoto
We theoretically investigate current noise in metallic carbon nanotubes induced by electron-phonon scattering, focusing on the probability density function (PDF) of the current that characterizes the nonequilibrium steady state. Quantum transport simulations combined with analyses of higher-order statistical moments reveal that the PDF evolves continuously from a Gaussian distribution in the ballistic regime to a non-Gaussian gamma distribution in the diffusive regime. In the crossover regime, the PDF exhibits pronounced asymmetry, attributed to a statistical imbalance in the number of conduction pathways contributing to high- and low-current events. Furthermore, in the diffusive regime, we identify non-Markovian features arising from high-frequency resonances in the current noise, which dominate the asymptotic scaling behavior of the current variance.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
7 pages, 6 figures
Optically Controlled Skyrmion Number Current
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Emir Syahreza Fadhilla, M Shoufie Ukhtary, Ardian Nata Atmaja, Bobby Eka Gunara
We propose a mechanism to control the motion of magnetic Skyrmions through the generation of a Skyrmion number current. This current is induced and tuned by an explicitly time-dependent Hamiltonian that includes a Zeeman term arising from the interaction between the spin system and circularly polarized light. To capture the effect, we apply a first-order perturbation method to the Landau-Lifshitz-Gilbert equation, using a breathing Skyrmion ansatz based on the Belavin-Polyakov profile. This approach reveals that the time-dependent deformation of the Skyrmion boundary produces an anisotropic breathing mode, which in turn generates a nonzero Skyrmion number current. The resulting dynamics in momentum space form a limit cycle, whose characteristics depend solely on the external magnetic field amplitude, the Heisenberg exchange coupling, and the Gilbert damping constant. Our formulation not only clarifies the topological origin of optically driven Skyrmion motion but also points to Skyrmion number currents as a low-dissipation alternative to electric currents for efficient Skyrmion control.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Mathematical Physics (math-ph)
14 pages, 5 figures
Solid-Angle Nearest-Neighbor Method for Size-Disperse Systems of Spheres
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-18 20:00 EDT
Nydia Roxana Varela-Rosales, Michael Engel
Identifying nearest neighbors accurately is essential in particle-based simulations, from analyzing local structure to detecting phase transitions. While parameter-free methods such as Voronoi tessellation and the solid-angle nearest-neighbor (SANN) algorithm are effective in monodisperse systems, they become less reliable in mixtures with large size disparities. We introduce SANNR, a generalization of SANN that incorporates particle radii into the solid-angle criterion for robust, size-sensitive neighbor detection. We compare SANNR against Voronoi, Laguerre, and SANN in binary and size-disperse sphere mixtures. Using Wasserstein distance metrics, we show that SANNR closely matches size-aware Laguerre tessellation while preserving the geometric continuity of SANN. Applied to the crystallization of the complex AB$ _{13}$ phase, SANNR improves detection of local bond-orientational order and better captures the emergence of global symmetry. SANNR thus offers a smooth, parameter-free, and extensible framework for neighbor detection in polydisperse and multicomponent systems.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
Uncovering the Fourier Structure of Wavefunctions in Semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Yunfan Liang, Damien West, Shengbai Zhang
Symmetry dictates the physical properties of materials. The symmetry of the Bravais lattice defines the set of points, lines, and planes over which sets of planewaves are degenerate, upon which atomic symmetry determines the interaction potentials which may lift such degeneracies. This results in wavefunctions which are single planewaves throughout the BZ, except in the vicinity of the removed degeneracies. As optical transitions between any two planewaves are forbidden, only regions of the Brillouin zone (BZ) near these lifted degeneracies contribute to optical properties. Application to optical response of Si and other semiconductors reveals that a single band transition, with only two planewaves, well describes their dielectric properties. Further, it provides a framework to understand non-linear optical response which is demonstrated to arise from higher order degeneracy existing along high symmetry lines/points of the BZ.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
Light Induced Quantum Anomalous Hall Effect in Cubic Rashba Spin-Orbit Coupled Systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
We investigate topological phase transitions in a two-dimensional electron system with cubic Rashba spin-orbit coupling driven by circularly polarized light. Within the Floquet framework, we demonstrate that light-matter interaction induces nontrivial band topology characterized by a quantized anomalous Hall response, with Chern insulating phases of C = 0, 1, and 3. These transitions are governed by gap closings at high-symmetry points in the Brillouin zone, controlled by the intensity and energy of the incident light. Introducing a weak linear Rashba term displaces Dirac points in momentum space without modifying the topology, whereas a purely linear Rashba system remains topologically trivial (C = 0). When both linear and cubic Rashba couplings are finite, the linear term confines nonzero-Chern phases to narrow parameter windows. In contrast, incorporating a linear Dresselhaus term into the cubic Rashba system can trigger topological transitions even at small coupling strengths. These results clarify the interplay between distinct spin-orbit interactions in Floquet-engineered Chern insulators and offer experimentally relevant pathways for achieving light-controlled topological phases.
Strongly Correlated Electrons (cond-mat.str-el)
First draft
Metallic Contact Contributions in Thermal Hall Conductivity Measurements
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Hongyu Ma, Xuesong Hu, Junren Shi
We investigate the influence of metallic contacts on thermal Hall measurements. By analyzing typical measurement configurations, we demonstrate that heat currents bypassing through metallic contacts can generate non-negligible thermal Hall signals, even when the actual thermal Hall conductivity of a measured insulator is zero. We show that the effect predicts thermal Hall conductivities that compare favorably with actual experimental observations across a variety of materials, reproducing both their temperature dependencies and magnitudes by assuming effective contact thicknesses on the order of 10$ ^{-2}$ of sample widths. It even reproduces the subtle differences in temperature dependencies between materials with high and low longitudinal thermal conductivity. Our study suggests the necessity of suppressing the bypass heat currents in thermal Hall measurements, which can be achieved by properly arranging the measurement configurations.
Materials Science (cond-mat.mtrl-sci)
Dissipation-Induced Steady States in Topological Superconductors: Mechanisms and Design Principles
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
M.S. Shustin, S.V. Aksenov, I.S. Burmistrov
The search for conditions supporting degenerate steady states in nonequilibrium topological superconductors is important for advancing dissipative quantum engineering, a field that has attracted significant research attention over the past decade. In this study, we address this problem by investigating topological superconductors hosting unpaired Majorana modes under the influence of environmental dissipative fields. Within the Gorini-Kossakowski-Sudarshan-Lindblad framework and the third quantization formalism, we establish a correspondence between equilibrium Majorana zero modes and non-equilibrium kinetic zero modes. We further derive a simple algebraic relation between the numbers of these excitations expressed in terms of hybridization between the single-particle wavefunctions and linear dissipative fields. Based on these findings, we propose a practical recipes how to stabilize degenerate steady states in topological superconductors through controlled dissipation engineering. To demonstrate their applicability, we implement our general framework in the BDI-class Kitaev chain with long-range hopping and pairing terms – a system known to host a robust edge-localized Majorana modes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
40 pages, 3 figures
Theory of Spiral Magnetism in Weyl semimetal SmAlSi
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Lasin Thaivalappil, Rahul Verma, Hsin Lin, Bahadur Singh, Shin-Ming Huang
Recent neutron scattering and thermodynamic measurements suggest that Weyl electrons in the emergent Weyl semimetal SmAlSi mediate unconventional magnetic interactions and induce spiral magnetic order. In this work, we investigate the nature of these interactions by modelling long-range $ f-f$ exchange mediated by itinerant $ d$ electrons via the Ruderman-Kittel-Kasuya-Yosida (RKKY) mechanism, employing a material-specific tight-binding Hamiltonian obtained from first-principles calculations. The magnetic susceptibility is derived from the spin-spin correlation function based on the random phase approximation. Our results demonstrate that Fermi-surface nesting alone cannot account for the experimentally observed magnetic modulation at the wave vector (1/3, 1/3, 0); however, incorporating appropriate antiferromagnetic exchange interactions among the $ d$ electrons yields the correct propagation vector. The spin-texture analysis reveals a configuration that is close to a cycloidal spin structure, preserving combined glide and time-reversal symmetry, and reflecting an intricate competition between inter- and intra-sublattice interactions in SmAlSi.
Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 4 figures
Quantum Time Crystals and Interacting Chiral Gauge Theories in Atomic BECs III: Role of the Page-Wootters mechanism
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
We build the case that our published chiral soliton model [Phys. Rev. Lett. 124, 250402 (2019)] can lead to a genuine quantum time crystal for smaller atom numbers. To do this we compare results from the chiral soliton model with exact numerical solutions for the ground state of the three-particle Schrödinger equation in the limit that the spatial profile of the soliton is largely independent of its center-of-mass motion. The connection between the two approaches is found via the Page-Wootters mechanism, and this is what allows for dynamical evolution even in the quantum ground state, as required for a genuine quantum time crystal.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
Large-scale dynamics in visual quorum sensing chiral suspensions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-18 20:00 EDT
Yuxin Zhou, Qingqing Yin, Shubhadip Nayak, Poulami Bag, Pulak K. Ghosh, Yunyun Li, Fabio Marchesoni
Motility induced phase separation is an efficient aggregation mechanism of active matter, yet biological systems exhibit richer organization through communication among constituents. We investigate suspensions of active particles that change chirality when neighbor density within their visual cone exceeds a threshold, a communication based non-reciprocal interaction akin to quorum sensing. Tuning the visual cone triggers programmable transitions: from disorder to phase separation to hyper-uniformity. Notably, phase separation triggers large-scale circulation, with robust edge currents persistently flowing around dense clusters, while particle distributions inside become effectively hyper-uniform. These are genuine non-reciprocal effects which occur even in the absence of steric interactions. Remarkably, in active-passive mixtures, only 5% quorum-sensing chiral particles suffice to induce collective circulation. Thus, simple perception-based rules can generate life-like order, offering design principles for programmable active materials and micro-robotic swarms.
Soft Condensed Matter (cond-mat.soft), Applied Physics (physics.app-ph)
Unified Field-integral Thermodynamics of Bose Mixtures: Stability and Critical Behavior
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
We establish a unified thermodynamic framework for Bose mixtures at finite temperatures based on the functional field integral, within which the decision on whether to discard the anomalous densities, when determining the density configuration and stability matrix, yields distinct theories. Beyond the existing Hartree-Fock approximation and Ota-Giorgini-Stringari theory, retaining the anomalous densities throughout will provide a completely self-consistent thermodynamic description, requiring the combination of the Hartree-Fock-Bogoliubov approximation and the representative statistical ensemble. Comparing three approaches for predicting magnetic susceptibility, we highlight the role of anomalous densities in stabilizing superfluid mixtures. We further unveil that Feshbach coupling can either expand the regime of atomic and molecular superfluids, or induce a phase transition to a pure molecular superfluid, depending on their density ratio. Importantly, we show that thermal fluctuations will trigger a phase transition from stable to unstable mixtures, where anomalous densities can serve as distinct signatures for experimental observation.
Quantum Gases (cond-mat.quant-gas), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
7+3 pages, 3 figures (comments are welcome)
Atomistic spin dynamics with quantum colored noise
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Fried-Conrad Weber, Felix Hartmann, Matias Bargheer, Janet Anders, Richard F. L. Evans
The accurate prediction of temperature-dependent magnetization dynamics is a fundamental challenge in computational magnetism. While Atomistic Spin Dynamics (ASD) simulations have emerged as a powerful tool for studying magnetic phenomena, their classical nature leads to significant deviations from experimental observations, particularly at low temperatures. Here we present a comprehensive implementation of quantum-corrected ASD into the Vampire software package, based on the open-system Landau-Lifshitz-Gilbert equation with a quantum thermostat. Our implementation incorporates memory effects along with colored noise derived from quantum-mechanical considerations that improve the description of the equilibrium magnetization. We demonstrate excellent quantitative agreement with experimental magnetization curves for nickel and gadolinium across the full temperature range. Our results establish that incorporating quantum environmental effects and colored noise substantially enhances the predictive capabilities of ASD simulations, providing a robust framework for modeling temperature-dependent magnetic phenomena in localized moment magnetic systems.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
13 pages, 7 figures, 3 tables, comments are welcome
Enhanced anomalous Hall conductivity via Ga doping in Mn\textsubscript{3}Sn and Mn\textsubscript{3}Ge
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Chenyue Wen, Danrong Xiong, Chengyi Yang, Dapeng Zhu, Weisheng Zhao
This study examines the anomalous Hall effect (AHE) in the Heusler series \ce{Mn3Z} (Z=Ga, Ge, Sn), with a particular emphasis on the manipulation of non-collinear antiferromagnetic structures to enhance AHE. By employing density-functional theory and first-principles calculations, we demonstrate that the anomalous Hall conductivity is markedly responsive to electron filling. By strategically doping Ga into \ce{Mn3Sn} and \ce{Mn3Ge} in order to modulate the electron density, a significant increase in anomalous Hall conductivity (AHC) is achieved. It is noteworthy that a Ga:Sn ratio of 1:5 yields peak AHC values exceeding $ \mathrm{700(\Omega \cdot cm)^{-1}}$ , while 3:7 Ga-Ge ratios can result in AHC values surpassing $ 600\mathrm{(\Omega \cdot cm)^{-1}}$ . A comparison between the virtual crystal approximation and supercell construction methods for doping has revealed consistent trends. The results of this study pave the way for optimizing AHE in non-collinear AFM materials.
Materials Science (cond-mat.mtrl-sci)
Fermi-liquid-like phase driven by next-nearest-neighbor couplings in a lightly doped kagome-lattice $t$-$J$ model
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Xu-Yan Jia (1), Fan Yang (2), D. N. Sheng (3), Shou-Shu Gong (4 and 5) ((1) School of Physics, Beihang University, (2) School of Physics, Beijing Institute of Technology, (3) Department of Physics and Astronomy, California State University Northridge, Northridge, (4) School of Physical Sciences, Great Bay University, (5) Great Bay Institute for Advanced Study)
Due to the interplay between charge fluctuation and geometry frustration, the doped kagome-lattice Mott insulator is a fascinating platform to realize exotic quantum states. Through the state-of-the-art density matrix renormalization group calculation, we explore the quantum phases of the lightly doped kagome-lattice $ t$ -$ J$ model in the presence of the next-nearest-neighbor electron hopping $ t_2$ and spin interaction $ J_2$ . On the $ L_y = 3$ cylinder ($ L_y$ is the number of unit cells along the circumference direction), we establish a quantum phase diagram with tuning $ t_2 > 0$ and $ J_2 > 0$ , showing an emergent Fermi-liquid-like phase driven by increased $ t_2$ and $ J_2$ , which sits at the neighbor of the previously identified charge density wave (CDW) phase. Compared with the CDW phase, the charge order is significantly suppressed in the Fermi-liquid-like phase, and most correlation functions are greatly enhanced with power-law decay. In particular, we find the absence of hole pairing and a strong three-sublattice magnetic correlation. On the wider $ L_y = 4$ cylinder, this Fermi-liquid-like phase persists at low doping levels, strongly suggesting that this state might be stable in the two-dimensional kagome system.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Pink noise in Electric Current from Amplitude Modulations
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
Masahiro Morikawa, Akika Nakamichi
We recently proposed that the general origin of 1/f fluctuation, or pink noise, is the amplitude modulation (or beat) of many waves with accumulating frequencies. In this paper, we verify this proposal in the electric current system. We use the classical Langevin equation to describe the electron wave packets flowing in the (semi-)conductor, affected by the back reaction of soft photon emission. If this were amplitude modulation, a demodulation process is needed to extract the fluctuation features. We first square the wave packet, which corresponds to the electric current, and obtain the 1/f fluctuation in this current data. We further speculate that this wave packet, after demodulation by thresholding, triggers the time sequence of the nerve firing. In our model, this also shows 1/f fluctuations, which is quite robust.
Statistical Mechanics (cond-mat.stat-mech)
5 pages, 7 figures
IEEE Conference: 2023 First International Conference on Advances in Electrical, Electronics and Computational Intelligence (ICAEECI)
Pairwise correlations of global times in one-dimensional Brownian motion under stochastic resetting
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
Brownian motion with stochastic resetting-a process combining standard diffusion with random returns to a fixed position-has emerged as a powerful framework with applications spanning statistical physics, chemical kinetics, biology, and finance. In this study, we investigate the mutual correlations among three global characteristic times for one-dimensional resetting Brownian motion $ x(\tau)$ over the interval $ \tau \in \left[ 0, t\right] $ : the occupation time $ t_o$ spent on the positive semi-axis, the time $ t_m$ at which $ x(\tau)$ attains its global maximum, and the last-passage time $ t_{\ell}$ when the process crosses the origin. For the process starting from the origin and undergoing Poissonian resetting back to the origin, we analytically compute the pairwise joint distributions of these three times (in the Laplace domain) and derive their pairwise correlation coefficients. Our results reveal that these global times display rich correlations, with a non-trivial dependence on the resetting rate $ r$ . Specifically, we find that (i) While $ t_{o}$ and $ t_{\ell}^m$ are uncorrelated for any positive integer $ m$ , $ t_{o}^2$ and $ t_{\ell}^m$ display anti-correlation; (ii) A positive correlation exists between $ t_{o}$ and $ t_{m}$ , which decays toward zero following a logarithmically corrected power-law way with an exponent of $ -2$ as $ r \to \infty$ ; (iii) The correlation between $ t_{m}$ and $ t_{\ell}$ shifts from positive to negative as $ r$ increases. All analytical predictions are validated by extensive numerical simulations.
Statistical Mechanics (cond-mat.stat-mech)
21 pages, 7 figures
A 3D porous MXene/PNIPAAm hydrogel composite with advanced degradation stability and control of electronic properties in air
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-18 20:00 EDT
Sitao Wang, Chen Jiao, Gerald Gerlach, Julia Körner
This study reports the fundamental investigation of a novel composite material consisting of MXene (Ti$ _3$ C$ _2$ T$ _x$ ) and a stimulus-responsive hydrogel (Poly(N-isopropylacrylamide) - PNIPAAm). In contrast to previously reported integration of MXene and hydrogels, the material described here offers a tunable porous structure for volatile organic compound (VOC) sensing that maintains its stability and responsiveness in any kind of gaseous environment and in a dried state. Furthermore, its synthesis is significantly simpler and more efficient compared to other studies on porous MXene composites. The presented study focuses on a fundamental investigation of the synthesized MXene/PNIPAAm composite’s properties. Thereby, the fabrication and comparison of pure MXene and composite samples featuring either a compact or a highly porous three-dimensional microstructure, reveal unique properties with respect to: (i) controllable three-dimensional spatial arrangement of MXene instead of the prevalent stacked-sheet structure, (ii) reduction of oxidation-induced degradation of MXene and substantially enhanced stability over the course of three months, and (iii) tunable electronic states in response to gas interactions. Material characterization is conducted by scanning electron microscopy and rheology to assess the microstructural and mechanical properties, and in a chemiresistive measurement setup for determination of electrical properties and the evaluation of the composite’s potential for VOC sensing in a gaseous environment with the test analyte acetone. These investigations reveal fundamentally novel material effects and properties that address some of the key MXene-related challenges. Additionally, the interplay between the MXene and the hydrogel enables unprecedented opportunities for enhancing the sensing potential of stimulus-responsive hydrogels, specifically in gaseous environments.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Contains supporting information at the end
Analytical study of a finite-range impurity in a one-dimensional Bose gas
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-08-18 20:00 EDT
T. Alper Yoğurt, Matthew T. Eiles
One-dimensional Bose gases present an interesting setting to study the physics of Bose polarons, as density fluctuations play an enhanced role due to reduced dimensionality. Theoretical descriptions of this system have predominantly relied on contact pseudopotentials to model the impurity-bath interaction, leading to unphysical results in the strongly coupled limit. In this work, we analytically solve the Gross-Pitaevskii equation, using a square well potential instead of a zero-range potential, for the ground-state wave function of a static impurity. We compute perturbative corrections arising from infinitesimally slow impurity motion. The polaron energy and effective mass remain finite in the strongly coupled regime, in contrast to the divergent behavior obtained using a contact potential. Moreover, we provide a universal description in this limit characterized by the dimensionless ratio $ \bar{w} \equiv w/\xi$ between the interaction range $ w$ of the impurity-bath potential and the coherence length $ \xi$ of the Bose gas. The effective mass exhibits a $ 1/ \bar{w}$ scaling. The energy of the attractive polaron scales as $ -1/\bar{w}^3$ , whereas the repulsive polaron features subleading corrections to the dark soliton energy at the order $ \bar{w}^3$ .
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph)
Hole doping as an efficient route to increase the Curie temperature in monolayer CrI$_3$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Marko Orozović, Božidar N. Šoškić, Silvia Picozzi, Željko Šljivančanin, Srdjan Stavrić
Two-dimensional van der Waals (vdW) magnets offer unprecedented opportunities to control magnetism at the atomic scale. Through charge carrier doping - realized by electrostatic gating, intercalation/adsorption, or interfacial charge transfer - one can efficiently tune exchange interactions and spin-orbit-induced effects in these systems. In this work, through a multi-scale theoretical framework combining density functional theory, spin Hamiltonian modeling, and Wannier-function analysis, we choose monolayer CrI$ _3$ to unravel how carrier doping affects the isotropic as well as anisotropic exchange interactions in this prototypical vdW ferromagnet. The remarkable efficiency of hole doping in enhancing ferromagnetic exchange and magnetic anisotropy found in our study was explained through orbital-resolved analysis. Crucially, we demonstrated that unlike the undoped system - where isotropic exchange interactions govern magnetic long-range order - the hole-doped CrI$ _3$ exhibits anisotropic terms comparable in magnitude to isotropic ones. Finally, we show that a high concentration of holes in a CrI$ _3$ monolayer can increase its Curie temperature above 200 K. This work advances our understanding of doping-controlled magnetism in semiconducting 2D materials, demonstrating how anisotropy engineering can stabilize high-temperature magnetic order.
Materials Science (cond-mat.mtrl-sci)
10 pages, 5 figures, supplementary information is included at the end of the manuscript
The contribution of electron and hole conductivity to the transport loss in organic solar cells
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Chen Wang, Toni Seiler, Doyoung Sun, Safa Shoaee, Maria Saladina, Carsten Deibel
The effective conductivity determines the reciprocal of the transport resistance, the dominant loss of fill factor in organic solar cells. We experimentally determine the dependence of effective conductivity on its electron and hole contributions. Using PM6:Y12 blends with tunable morphological and energetic disorder, we show that the effective conductivity follows a harmonic mean of electron and hole conductivities even across nearly three orders of magnitude in conductivity imbalance. We also validate the method for directly extracting effective conductivity from current-voltage measurements, eliminating the need to rely on indirect mobility and charge carrier density-based proxies. Our findings challenge the widespread use of geometric mean approximations and offer a more accurate framework for analysing and modelling transport in disordered organic semiconductors.
Materials Science (cond-mat.mtrl-sci)
Realistic modelling of transport properties at finite tempeature in magnetic materials by local quantization of a Heisenberg model
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Fabian Engelke, Christian Heiliger
The quantitative description of the electrical resistivity of a magnetic material remains challenging to this day. Qualitatively, it is well understood that the temperature-induced lattice and spin disorder determines the temperature dependence of the resistivity. While prior publications reached good agreement with experiment in the so-called supercell or direct approach for non-magnetic materials where the spin-disorder contribution to the resistivity is negligible, an accurate, purely theoretical description of magnetic materials remains elusive. This shortcoming can be attributed to the missing accuracy in the description of the temperature-dependent spin-disorder itself. In this work, we employ a joint approach from \textit{ab-initio} transport calculations and atomistic modeling of the temperature-dependent spin-disorder. Using the example of $ \alpha$ -Fe, we demonstrate that the inclusion of quantum mechanical effects using a semiclassical local quantization of the Heisenberg model significantly improves the description of the spin-disorder component to the electrical resistivity. Compared to previous approaches, this model includes the description of magnetic short-range order effects, enabling us to study temperature effects around and above the Curie temperature, where prior mean-field theory-based approaches inevitably predicted a constant contribution.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Thermodynamically Consistent Coarse-graining: from Interacting Particles to Fields via Second Quantization
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
Atul Tanaji Mohite, Heiko Rieger
We systematically derive an exact coarse-grained description for interacting particles with thermodynamically consistent stochastic dynamics, applicable across different observation scales, the mesoscopic and the macroscopic. We implement the coarse-graining procedure using the Doi-Peliti field theory, which preserves microscopic noise effects on the meso/macro scale. The exact mapping reveals the key role played by Poissonian particle occupancy statistics. We show the implications of the exact coarse-graining method using a prototypical flocking model, namely the active Ising model, which exhibits a mismatch between the microscopic and macroscopic mean-field coarse-grained descriptions. Our analysis shows that the high- and low-density regimes are governed by two different coarse-grained equations. In the low-density regime, noise effects play a prominent role, leading to a first-order phase transition. In contrast, the second-order phase transition occurs in the high-density regime. Due to the exact coarse-graining methods, our framework also opens up applicability to systematically analyze noise-induced phase transitions in other models of reciprocally and non-reciprocally interacting particles.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Spin-to-charge-current conversion in altermagnetic candidate RuO$_2$ probed by terahertz emission spectroscopy
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
J. Jechumtál, O. Gueckstock, K. Jasenský, Z. Kašpar, K Olejník, M. Gaerner, G. Reiss, S. Moser, P. Kessler, G. De Luca, S. Ganguly, J. Santiso, D. Scheffler, J. Zázvorka, P. Kubaščík, H. Reichlova, E. Schmoranzerova, P. Němec, T. Jungwirth, P. Kužel, T. Kampfrath, L. Nádvorník
Using the THz emission spectroscopy, we investigate ultrafast spin-to-charge current conversion in epitaxial thin films of the altermagnetic candidate RuO$ _2$ . We perform a quantitative analysis of competing effects that can contribute to the measured anisotropic THz emission. These include the anisotropic inverse spin splitter and spin Hall effects in RuO$ _2$ , the anisotropic conductivity of RuO$ _2$ , and the birefringence of the TiO$ _2$ substrate. We observe that the leading contribution to the measured signals comes from the anisotropic inverse spin Hall effect, with an average spin-Hall angle of $ 2.4\times 10^{-3}$ at room temperature. In comparison, a possible contribution from the altermagnetic inverse spin-splitter effect is found to be below $ 2\times 10^{-4}$ . Our work stresses the importance of carefully disentangling spin-dependent phenomena that can be generated by the unconventional altermagnetic order, from the effects of the relativistic spin-orbit coupling.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
21 pages, 4 figures
Exceptionally deficient topological square-root insulators
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Subhajyoti Bid, Henning Schomerus
One of the most surprising features of effectively non-Hermitian physical systems is their potential to exhibit a striking nonlinear response and fragility to small perturbations. This feature arises from spectral singularities known as exceptional points, whose realization in the spectrum typically requires fine-tuning of parameters. The design of such systems receives significant impetus from the recent conception of \emph{exceptional deficiency}, in which the entire energy spectrum is composed of exceptional points. Here, we present a concrete and transparent mechanism that enforces exceptional deficiency through lattice sum rules in non-Hermitian topological square-root insulators. We identify the resulting dynamical signatures in static broadband amplification and non-Abelian adiabatic state amplification, differentiate between bulk and boundary effects, and outline routes to implementation in physical platforms
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics), Quantum Physics (quant-ph)
6 pages, 3 figures
Gating upconversion electroluminescence in a single molecule via adsorption-induced interaction of unpaired spin
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Vibhuti N. Rai, Christof Holzer, Carsten Rockstuhl, Wulf Wulfhekel, Lukas Gerhard
Molecules with unpaired spins (radicals) offer promising alternatives to closed-shell molecules as they are less limited regarding the spin statistics in their electroluminescence. Here, we combine scanning tunneling microscopy induced luminescence and density functional theory to study single vanadyl phthalocyanine molecules, which are stable neutral radicals. Two distinct adsorption geometries of the molecule on NaCl/Au(111) lead to a difference in the interaction of the unpaired electron with the substrate, which in turn allows us to investigate its effects on the light emission process. Remarkably, we observe that up-conversion electroluminescence is gated by the adsorption geometry of the molecule, an effect we attribute to a reordering of excited states and enhanced excited state transition probabilities. The profound influence of the unpaired electron via state reordering opens new possibilities for tuning not only molecular electroluminescence but also many other spin dependent phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 8 figures
pylimer-tools: A Python Package for Generating and Analyzing Bead-Spring Polymer Networks
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-08-18 20:00 EDT
Tim Bernhard, Fabian Schwarz, Andrei A. Gusev
The Python package pylimer-tools is a comprehensive toolkit for computational studies of polymer networks, particularly bead-spring networks. The package provides functionality to generate polymer networks using Monte Carlo (MC) procedures and analyze their structural and mechanical properties. Key features include detection of loops, reduction of the network to its ground state energy both with and without entanglements by the Force Balance procedure, and thereafter computing the soluble and dangling fractions of network strands, as well as the equilibrium shear modulus. The toolkit supports analysis of structures generated both internally and by external simulation software such as LAMMPS. The package implements theoretical frameworks including Miller-Macosko theory and provides a dissipative particle dynamics (DPD) simulator with slip-spring entanglement modeling. Built with C++ for performance and exposed through Python bindings, pylimer-tools addresses the need for specialized tools in computational polymer science.
Soft Condensed Matter (cond-mat.soft), Computational Physics (physics.comp-ph)
12 pages, 1 figure
Quantum Quench Dynamics in an Exactly Solvable Two-Dimensional Non-Fermi Liquid System
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-08-18 20:00 EDT
Hui Li, Run-Yu Chen, Wen-Yuan Liu, Yin Zhong, Hai-Qing Lin
Understanding the behavior of non-Fermi liquids (NFLs) is an important topic in condensed matter physics. Here we introduce an exactly solvable multi-orbital model based on iron oxypnictides and the Hatsugai-Kohmoto model, and provide exact investigations of the 2D NFLs nonequilibrium physics present in this model. Our results reveal fundamental departures from Fermi liquids and prior NFLs in the well-know SYK model: anomalous short-time scaling $ -\tau^2 \ln \tau$ , $ O(\tau) \sim \tau^2$ ; long-time scaling $ \tau^{-1}, \tau^{-1/2}, \ln \tau / \tau$ ; a strange critical behavior in the steady-state phase diagram. Our asymptotic results and dynamical critical behavior offer new insights into the orbital-related dynamical physics of 2D NFLs.
Strongly Correlated Electrons (cond-mat.str-el)
8 pages,5 figures
A Dynamical Bulk-Boundary Correspondence in Two Dimensional Topological Matter
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
Tomasz Masłowski, Jesko Sirker, Nicholas Sedlmayr
Dynamical quantum phase transitions occur when a dynamical free energy becomes non-analytic at critical \emph{times}. They have been shown to exist in, among other systems, topological insulators and superconductors. Additionally in both one dimensional systems and two dimensional higher order topological matter a dynamical analogue of the bulk-boundary correspondence has been observed which is suggestive of a dynamical switching between different phases. If the time evolving Hamiltonian is topologically non-trivial, zeroes of the Loschmidt matrix appear between critical times, leading to significant, periodically occurring contributions to the boundary dynamical free energy. In this article we extend these ideas to two dimensional topological matter by showing that in-gap bands in the spectrum of the Loschmidt matrix between successive critical times exist if the time evolving Hamiltonian is topologically non-trivial. We further show that these in-gap bands are directly responsible for a boundary contribution to the dynamical free energy, thus establishing a dynamical bulk-boundary correspondence in two dimensional topological matter.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Ultrafast X-ray interaction with photovoltaic materials: Thermal and nonthermal responses
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-08-18 20:00 EDT
Aldo Artímez Peña, Nikita Medvedev
Cadmium telluride (CdTe), lead sulfide (PbS), and indium tin oxide (ITO) are important in various electronic technologies, for which laser irradiation is used to selectively modify and design their unique semiconductor properties. We employ the hybrid multiscale code XTANT-3 to simulate the kinetics of material response to ultrafast X-ray irradiation. The code accounts for nonequilibrium electronic and atomic dynamics, nonadiabatic coupling, nonthermal melting, and bond breaking due to electronic excitation. Among the materials studied, CdTe exhibits the highest radiation resistance, similar to CdS. At the respective threshold doses, the melting is primarily thermal, driven by electron-phonon coupling, which is accompanied by the band gap closure. Additionally, all materials show nonthermal melting at higher doses. Threshold doses increase further if energy sinks and recrystallization are included. In CdTe and PbS, below 1.5 eV/atom, the band gap returns to its original value upon recrystallization. As the dose increases, the cooled state becomes more amorphous, reducing the band gap until it stabilizes. Curiously, in a narrow window of deposited doses, ITO exhibit transient superionic behavior, with the liquid oxygen but solid In and Sn sublattices. At 0.6 eV/atom in CdTe and 0.4 eV/atom in PbS and ITO, material ablation from the surface occurs. The results suggest that femtosecond lasers may be used for tuning the band gap of photovoltaic semiconductors.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other)
26 pages, 22 figures, 2 tables. arXiv admin note: text overlap with arXiv:2502.05799
Stabilizing and Tuning Superconductivity in La$_3$Ni$2$O${7-δ}$ Films: Oxygen Recycling Protocol Reveals Hole-Doping Analogue
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-18 20:00 EDT
Lifen Xiang, Siyi Lei, Xiaolin Ren, Ziao Han, Zijian Xu, X.J. Zhou, Zhihai Zhu
The recent achievement of superconductivity in La$ _3$ Ni$ _2$ O$ _{7-\delta}$ with transition temperatures exceeding 40 K in thin films under compressive strain and 80 K in bulk crystals under high pressure opens new avenues for research on high-temperature superconductivity. The realization of superconductivity in thin films requires delicate control of growth conditions, which presents significant challenges in the synthesis process. Furthermore, the stability of superconducting La$ _3$ Ni$ _2$ O$ _{7-\delta}$ films is compromised by oxygen loss, which complicates their characterization. We introduce an effective recycling protocol that involves oxygen removal in a precursor phase followed by ozone-assisted annealing, which restores superconducting properties. By tuning the oxygen content, we construct an electronic phase diagram that highlights oxygen addition as a potential analogue to hole doping via La substitution with Sr, providing insights into the doping mechanism and guiding future material optimization.
Superconductivity (cond-mat.supr-con)
Measuring irreversibility by counting: a random coarse-graining framework
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-08-18 20:00 EDT
Ruicheng Bao, Naruo Ohga, Sosuke Ito
Thermodynamic irreversibility is a fundamental concept in statistical physics, yet its experimental measurement remains challenging, especially for complex systems. We introduce a novel random coarse-graining framework to identify model-free measures of irreversibility in complex many-body systems. These measures are constructed from the asymmetry of cross-correlation functions between suitably chosen observables, providing rigorous lower bounds on entropy production. For many-particle systems, we propose a particularly practical implementation that divides real space into virtual boxes and monitors particle number densities within them, requiring only simple counting from video microscopy, without single-particle tracking, trajectory reconstruction, or prior knowledge of interactions. Owing to its generality and minimal data requirements, the random coarse-graining framework offers broad applicability across diverse nonequilibrium systems.
Statistical Mechanics (cond-mat.stat-mech), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
4+2 pages, 2 figures, comments are welcome
Low barrier ZrO$_x$-based Josephson junctions
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-18 20:00 EDT
Jaehong Choi, Maciej Olszewski, Luojia Zhang, Zhaslan Baraissov, Tathagata Banerjee, Kushagra Aggarwal, Sarvesh Chaudhari, Tomás A. Arias, David A. Muller, Valla Fatemi, Gregory D. Fuchs
The Josephson junction is a crucial element in superconducting devices, and niobium is a promising candidate for the superconducting material due to its large energy gap relative to aluminum. AlO$ _x$ has long been regarded as the highest quality oxide tunnel barrier and is often used in niobium-based junctions. Here we propose ZrO$ _x$ as an alternative tunnel barrier material for Nb electrodes. We theoretically estimate that zirconium oxide has excellent oxygen retention properties and experimentally verify that there is no significant oxygen diffusion leading to NbO$ _x$ formation in the adjacent Nb electrode. We develop a top-down, subtractive fabrication process for Nb/Zr-ZrO$ _x$ /Nb Josephson junctions, which enables scalability and large-scale production of superconducting electronics. Using cross sectional scanning transmission electron microscopy, we experimentally find that depending on the Zr thickness, ZrO$ _x$ tunnel barriers can be fully crystalline with chemically abrupt interfaces with niobium. Further analysis using electron energy loss spectroscopy reveals that ZrO$ _x$ corresponds to tetragonal ZrO$ _2$ . Room temperature characterization of fabricated junctions using Simmons’ model shows that ZrO$ _2$ exhibits a low tunnel barrier height, which is promising in merged-element transmon applications. Low temperature transport measurements reveal sub-gap structure, while the low-voltage sub-gap resistance remains in the megaohm range.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
32 pages in manuscript format
A non-Hermitian Su-Schrieffer-Heeger model with the energy levels of free parafermions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-08-18 20:00 EDT
Using a parent Hermitian tight-binding model on a bipartite lattice with chiral symmetry, we theoretically generate non-Hermitian models for free fermions with $ p$ orbitals per unit cell satisfying a complex generalization of chiral symmetry. The $ p$ complex energy bands in $ k$ space are given by a common $ k$ -dependent real factor, determined by the bands of the parent model, multiplied by the $ p$ th roots of unity. When the parent model is the Su-Schrieffer-Heeger (SSH) model, the single-particle energy levels are the same as those of free parafermion solutions to Baxter’s non-Hermitian clock model. This construction relies on fully unidirectional hopping to create Bloch Hamiltonians with the form of generalized permutation matrices, but we also describe the effect of partial unidirectional hopping. For fully bidirectional hopping, the Bloch Hamiltonians are Hermitian and may be separated into even and odd parity blocks with respect to inversion of the orbitals within the unit cell. Partially unidirectional hopping breaks the inversion symmetry and mixes the even and odd blocks, and the real energy spectrum evolves into a complex one as the degree of unidirectionality increases, with details determined by the topology of the parent model and the number of orbitals per unit cell, $ p$ . We describe this process in detail for $ p=3$ and $ p=4$ with the SSH model. We also apply our approach to graphene, and show that $ AA$ -stacked bilayer graphene evolves into a square root Hamiltonian of monolayer graphene with the introduction of unidirectional hopping. We show that higher-order exceptional points occur at edge states and solitons in the non-Hermitian SSH model, and at the Dirac point of non-Hermitian graphene.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
14 pages, 6 figures
The superconducting diode effect in Josephson junctions fabricated from structurally chiral Mo$_3$Al$_2$C
New Submission | Superconductivity (cond-mat.supr-con) | 2025-08-18 20:00 EDT
Peter T. Orban, Gregory Bassen, Evan N. Crites, Maxime A. Siegler, Tyrel M. McQueen
The superconducting diode effect occurs in superconducting materials in which both spin and inversion symmetry are broken. The recently observed chirality-induced spin selectivity effect demonstrates that chiral materials break both symmetries. Thus a Josephson junction interface with the left-handed structure on one side of the junction and the right-handed structure on the other should exhibit a diode effect. Here, we report the electrical transport properties of right-handed/left-handed and right-handed/right-handed devices fabricated from single crystals of the structurally chiral superconductor Mo$ 3$ Al$ 2$ C. A magnetic-field-induced superconducting diode effect is demonstrated in both devices by a statistically significant difference in $ I{c+}$ and $ |I{c-}|$ , and we show evidence for a zero-field diode effect in the right-handed/left-handed device but not the right-handed/right-handed device. A maximum asymmetry of 5% is observed in both devices. We provide a few explanations for the presence of the superconducting diode effect in these devices.
Superconductivity (cond-mat.supr-con)
The main text contains 7 figures, and the supporting information (included in the anc folder) contains 22 Figures