Strongly Correlated Electrons
Finite-Temperature Ferromagnetic Correlations of the Kagome Lattice Hubbard Model
Francisco Correia, Kyle Corbett and Ehsan Khatami
The Kagome
lattice Fermi-Hubbard model is one of the most physically rich, and at the same time most challenging, models to study in strongly-correlated physics. Among its special features are
geometric frustration and a flat energy band that create conditions favorable to ferromagnetism near the band insulating limit. Here, we utilize two exact finite-temperature methods, the numerical linked-cluster expansion and the determinant
quantum Monte Carlo, to study the extent as well as doping and interaction dependence of
ferromagnetic correlations and other thermodynamic properties of the model. We find that repulsive interactions enhance
ferromagnetic correlations at high electron densities and that increasing the interaction strength, extends the region with strong
ferromagnetic correlations towards half filling, smoothly connecting it to Nagaoka ferromagnetism near the Mott insulating region. We also use the charge compressibility to obtain an accurate estimate for the critical interaction strength for the metal-
insulator transition at half filling. These results improve our understanding of the
magnetic tendencies of the model away from half filling and pave the way for further studies, including with ultracold atoms in optical
lattices.
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Soft Condensed Matter
Programmable Persistent Random Walks in Active Brownian Particles Govern Emergent Dynamics
Tarun Sunkesula Raghavendra, Yogesh Shelke, Stijn van der Ham et al. (+2 more)
Self-propelled particles serve as minimal models for emulating the dynamic self-organization of microorganisms, yet most synthetic systems remain limited to a single mode of motion, namely active Brownian particles (ABPs). Here, we present an experimental strategy to encode various persistent random walks in ABPs by combining light-modulated propulsion strength with
magnetic control of propulsion direction. Our system enables programmable Levy walks with tunable step-length distributions, run-and-tumble dynamics, self-avoiding random walks, and Gaussian walks, with on-demand switching between motion modes within a single experiment. In addition, particles are steered along complex trajectories such as Fibonacci spirals and nested polygons. Beyond single-particle behavior, we show that propulsion modes influence clustering dynamics by comparing ABPs with
chiral active particles undergoing circular motion. These results establish a versatile platform for investigating how encoded motion at the level of individual particles governs transport, search strategies, and emergent organization in active matter systems.
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All authors Tarun Sunkesula Raghavendra, Yogesh Shelke, Stijn van der Ham, Anpuj Nair S, Hanumantha Rao Vutukuri
Superconductivity
Negative nonlocal and local voltages (resistances) in a quasi-one-dimensional superconducting aluminum structure
V.I. Kuznetsov and O.V. Trofimov
To study a nonlocal electron transport in an aluminum superconducting quasi-one-dimensional structure, we measured negative nonlocal (local) direct current voltages in the structure in a
magnetic field near the critical temperature. The structure is a normal-superconducting at $T_{cn}<T<T_{cw}$ ($T_{cn}$ and $T_{cw}$ are the critical temperatures for narrow and wide wires, respectively, making up this structure). Negative voltage arises due to a quasiparticle current flowing through the N-S interface. We plotted the experimental and theoretical temperature and
magnetic-field dependences of current, resistance and voltage corresponding to the peak of negative voltage, taking into account either
equilibrium or nonequilibrium superconducting fluctuations.
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Mesoscale and Nanoscale Physics
Transport characteristics of bulk and edge states in an off-diagonal Aubry–André–Harper chain
Moumita Patra
We investigate
quantum transport in an off-diagonal Aubry–André–Harper chain. The periodic hopping modulation generates effective internal boundaries that strongly influence the transmission characteristics. We show that edge, in-band bulk, and band-edge bulk states can be clearly distinguished through their transport signatures. In particular, bulk states near the band edges exhibit behavior similar to edge states, with weak dependence on system size, whereas in-band bulk states display pronounced size-dependent oscillations. We further demonstrate that the chain–electrode coupling strength controls the broadening of transmission resonances and drives a crossover from tunneling-dominated to nearly ballistic transport. In addition, dephasing introduces distinct sensitivity across different state classes, depending on their degree of spatial localization. These results highlight the key role of internal boundaries and
quantum coherence in governing transport in modulated one-dimensional systems.
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Strongly Correlated Electrons
Kondo transport in an anisotropic two-dimensional electron gas with quadratic momentum-dependent spin splitting
M. R. Parymuda
We investigate the transport properties of an anisotropic two-dimensional electron gas with a quadratic
spin texture, described by a low-energy effective $ k\cdot p$ model, in the presence of $S=1/2$ Kondo
impurities. We develop a Green's function framework that captures the interplay between the
spin texture and the Kondo scattering for calculating transport properties in such systems. Using this framework together with numerical renormalization group (NRG) calculations, we evaluate the longitudinal resistivity components $\rho^{xx}(T)$ and $\rho^{yy}(T)$ and analyze their temperature dependence. We further determine the Kondo temperature $T_K(\alpha)$ and the
impurity screening function $p(\alpha)$ and demonstrate that they decrease strongly with increasing quadratic
spin-splitting coupling $\alpha$.
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Strongly Correlated Electrons
Anisotropic metamagnetism and magnetotransport of heavy rare-earth orthorhombic single-crystal TbAlGe
Ram Kumar, K.E. Avers, V. Saini et al. (+10 more)
We report a comprehensive investigation of the anisotropic magnetism and
magnetic field-induced transitions in single
crystals of the orthorhombic system TbAlGe, a member of the topological RAlGe (R = rare-earth) family with the highest ordering temeprature in the RAlX (X = Si, Ge) series. With a single rare earth site with triangular coordination in its Cmcm orthorhombic unit
cell, TbAlGe harbors complex
magnetic interactions that yield two
antiferromagnetic transitions at 40 K and 8 K in zero field, and a rich cascade of metamagnetic transitions that only appear for fields directed along the crystallographic a-axis. Combining electrical resistivity, magnetization and heat capacity measurements with magnetotransport experiments performed up to 41.5 T, we construct a
magnetic phase diagram mapping the multiple
magnetic phases of TbAlGe, and discuss the complex interplay between localized 4f magnetism and itinerant electronic
topology, establishing TbAlGe as a compelling platform for exploring tunable
magnetic semimetal physics.
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All authors Ram Kumar, K.E. Avers, V. Saini, D. S. Sokratov, Y. Anand, P. Saraf, J. A. Horn, N. Brenowitz, S. Otazo, P. Sobel, D. Graf, S. R. Saha, J. Paglione
Mesoscale and Nanoscale Physics
Sub-50 Picosecond exceptionally Bright Perovskite Scintillation by Unlocking Giant Oscillator Strength
Chuanwei Dai, Yunbiao Zhao, Xiao Ouyang et al. (+11 more)
Ultrafast scintillators are indispensable for precise timing in high-energy physics and medical diagnostics. Fundamentally constrained by the trade-off between emission rate and light yield, conventional scintillators remain kinetically trapped in the sub-nanosecond regime, failing to break 50-picosecond limit. Here, we demonstrate a strategy to bypass this limitation by harnessing the coherent radiative acceleration in weakly confined CsPbCl3 perovskite nanocrystals to generate an ultrafast
photon burst. This effect originates from the
giant oscillator strength, which we unlock by suppressing
exciton-
phonon scattering at mild cryogenic temperatures. Consequently, our scintillator achieves an unprecedented dominant lifetime of 13.11 ps alongside a high light yield of 21,851 ph/MeV. The resulting
prompt photon emission rate more than 100 times higher than that of state-of-the-art ultrafast scintillators. We validate this breakthrough in realistic detection scenarios, achieving a coincidence time resolution of 30.8 ps and accurately resolving 13.5 ps electron bunches and 16.6 ps single-shot gamma-ray pulses. Our findings establish a robust coherent framework for next-generation ultrafast scintillators, pushing extreme radiation diagnostics into the picosecond frontier.
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All authors Chuanwei Dai, Yunbiao Zhao, Xiao Ouyang, Huaqing Huang, Yulan Liang, Jiaqi Bai, Yingjie Song, Jianhan Sun, Yiqun Duan, Wenjun Ma, Senlin Huang, Shufeng Wang, Jianming Xue, Xiaoping Ouyang
Mesoscale and Nanoscale Physics
Universal magnetotunnel conductance at a Weyl semimetal-layered Chern insulator junction
Nirnoy Basak, Sumathi Rao and Faruk Abdulla
We investigate electronic transport across a junction between a Weyl semimetal (WSM) and a layered Chern
insulator (LCI) in the presence of a
magnetic field perpendicular to the interface. The topological mismatch between the gapless Weyl semimetal and the momentum-resolved
chiral edge modes of the layered Chern
insulator leads to interface
Fermi-arc states with a qualitatively distinct connectivity: unlike WSM-WSM junctions, the interface
Fermi arcs are forced to reconnect through the Brillouin-zone boundary rather than terminating at the projections of the Weyl nodes. We analyze the spectrum and compute the magneto tunnel conductance mediated by the interface-localized states. We find that the conductance increases linearly with
magnetic field at low fields and saturates beyond a critical field to a constant value that is independent of microscopic details such as interface coupling, arc geometry, and
lattice-scale parameters. This universal saturation reflects a transport mechanism governed by the topological charge pumping associated with the Chern layers, rather than
magnetic breakdown between
Fermi arcs. We further show that, under specific conditions, a junction between two distinct Weyl semimetals can exhibit a similar saturation behavior, thereby clarifying the topological origin of the observed universality.
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Materials Science
Tracking visible pulsed laser annealing of Hf$_{0.5}$Zr$_{0.5}$O$_2$ heterostructures with in situ transmission electron microscopy
Aida Amini, Shruti Verma, Katharina Kohlmann et al. (+4 more)
Laser annealing offers a promising route to back end of the line fabrication of ferroelectric thin film transistors based on hafnium-zirconium
oxide (HZO). Due to the wide band gap of this material, previous reports have studied the crystallization of HZO using ultraviolet or infrared light. In contrast, we monitor its crystallization in a Si$_3$N$_4$/TiN/Hf$_{0.5}$Zr$_{0.5}$O$_2$ thin film
heterostructure upon irradiation with visible nanosecond
laser pulses. This geometry mimics the structure of CMOS devices and harnesses the absorption of TiN in the visible regime to generate the heat necessary for the transformation. Through a series of local in situ measurements using a modified transmission electron microscope, we quantify the relationship between the HZO film thickness, critical
laser energy density and the ferroelectric HZO phase fraction, finding a sharp threshold behavior in the
laser pulse energy necessary to crystallize HZO. The optimal condition of irradiating an 8-nm HZO film with a single
laser pulse with an energy density of 177 mJ/cm$^2$ is found to produce 86% of the ferroelectric orthorhombic phase. Heat transfer dynamics within the
heterostructure during
laser annealing are revealed by finite element simulations, where the partial melting of the silicon nitride substrate is found to play an important role limiting the temperature to 1900 {\deg}C. This finding as well as the observed
laser pulse energy threshold behavior support a kinetic crystallization pathway involving the tetragonal phase. More generally, these findings show how
laser-driven phase engineering can lead to scalable design and enhanced performance of ferroelectric materials in advanced electronic applications.
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All authors Aida Amini, Shruti Verma, Katharina Kohlmann, Sebastian Obernberger, Jean-Christof Lamanque, Andreas Rüdiger, Kenneth R. Beyerlein
Mesoscale and Nanoscale Physics
Non-Equilibrium Orbital Transport in Terahertz Optorbitronics
Sobhan Subhra Mishra and Ranjan Singh
Modern information technologies rely on controlling the flow of electrons through their charge and
spin. A rapidly emerging alternative is to use the orbital motion of electrons, the way they circulate around atomic sites as a new carrier of information. This orbital angular momentum (OAM) could enable more energy-efficient devices and reduce reliance on scarce heavy elements, but how orbital currents are generated and transported, especially on ultrafast timescales, remains largely unknown. In this review, we introduce terahertz optorbitronics, an approach that uses ultrafast femtosecond
laser pulses and terahertz radiation to observe orbital transport in real time. On timescales of quadrillionth of a second, this technique allows us to track how orbital currents are launched, propagate, and convert into electrical signals in nanoscale thin-film materials. Surprisingly, recent experiments have revealed conflicting pictures such as orbital currents may travel over tens of nanometres like ballistic waves or instead decay within just a few atomic layers, highlighting a fundamental unresolved question in the field. We explain how these ultrafast measurements can disentangle orbital motion from conventional
spin transport, and we highlight new materials from engineered
graphene to altermagnets, that could act as tunable sources of orbital currents. We also discuss how light, electrical gating, strain, and interface design can be used to actively control orbital transport and improve its conversion into usable electronic signals. By revealing orbital transport as a dynamic, non-
equilibrium process, terahertz optorbitronics opens a new direction for nanoscale science, the one that could lead to faster, more efficient technologies operating beyond the limits of conventional
spin-based electronics.
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Materials Science
Discovering physical mechanisms from experiment-simulation mismatches
Yue Li, Penghui Yang, Yushan Xiao et al. (+7 more)
Scientific discovery often begins where observation and prediction disagree. As computation and machine learning survey chemical space, experiment-simulation mismatches are exposed at scale, while tracing them to physical mechanisms remains expert-led. Here we present eXplainable DFT (XDFT), a self-evolving
agent that turns this process into an executable search. XDFT formalizes candidate mechanisms as executable hypotheses, adjudicates their consequences against experiment and distils trajectories into priors for later searches. This couples a solving loop from mismatch to mechanism with a learning loop through which solving changes the solver. Across 112 source-audited cases in which standard calculations predict a metal whereas experiments find a
semiconductor, XDFT resolved 105 with evidence-supported mechanisms within a single-GPU envelope. After 60 cases, the resolving mechanism ranked among the first three hypotheses for 80% of held-out cases, up from 7% under the initial expert prior. XDFT also returned evidence-graded mechanisms for seven expert-curated questions about physical mechanisms. These results establish experiment-simulation mismatches as tractable starting points for scientific
agents that discover physical mechanisms while learning how to find the next.
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All authors Yue Li, Penghui Yang, Yushan Xiao, Zhonghan Zhang, Jianguo Huang, Yuhao Lu, Cuntai Guan, Bo An, Bijun Tang, Zheng Liu
Mesoscale and Nanoscale Physics
Metalization of topological insulators
Xian-Peng Zhang, Yan-Qing Feng, Ji-Feng Shao et al. (+2 more)
In modern condensed matter theory, phases of electronic matter–such as metals and
insulators-are fundamentally distinguished by the presence or absence of charge-carrying quasiparticles or excitations near the
Fermi surface at low temperatures. Here, we show that this criterion breaks down in Berry-
curvature-dominated systems, where transport is governed by interband coherence across the entire
Fermi sea. We develop a microscopic theory of
quantum transport in bulk topological
insulators with a vanishing density of states at the
Fermi energy, for which the conventional Drude contribution is absent. We demonstrate that
impurity-scattering-induced coherence decay generates a distinct longitudinal transport channel even in the topologically trivial regime, with edge contributions rigorously excluded. This mechanism yields a finite longitudinal conductivity even in the absence of carriers at the
Fermi level and exhibits an unconventional scaling linear in
impurity density in the dilute limit, in stark contrast to Drude behaviour. Importantly, this decoherence-induced conductance is inversely proportional to temperature, reminiscent of strange-metal behaviour, most prominently observed in cuprate
superconductors above their critical temperature. Our findings reveal
quantum decoherence as a fundamental origin of longitudinal transport beyond the Drude paradigm, challenging the traditional distinction between metals and
insulators.
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All authors Xian-Peng Zhang, Yan-Qing Feng, Ji-Feng Shao, Haiwen Liu, Yugui Yao
Materials Science
Predicting massive helium-3 release from metal tritides using simple mechanical modeling
Berengere Evin, Dorian Gaboriau, Mathieu Segard et al. (+3 more)
This letter is presenting a simple but effective mechanism that explains why ,during tritium aging, metal tritides retain most helium-3 for years and then suddenly release massive amount. The mechanism is based on the hypothesis that dislocations blocking could explain the sudden change of behavior. The modeling of this phenomenon combine a mechanical and microstructural approach. The calculations made with this mechanism fit all the aging data acquired on aged palladium tritide
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All authors Berengere Evin, Dorian Gaboriau, Mathieu Segard, Sylvain Challet, Arnaud Fabre, Stephanie Thiebaut
Materials Science
Emergent surface resonance from charge density wave symmetry breaking in TiSe2
Turgut Yilmaz, Yi Sheng Ng, Muhammad Awais Fiaz et al. (+13 more)
Surface confined electronic states provide a fertile ground for discovering emergent phenomena that have no counterpart in the bulk, offering new routes to manipulate correlations,
symmetry breaking, and dimensionality at the atomic scale. Here, we show that charge density wave (CDW)
symmetry breaking can yield a surface states in 1T-TiSe2. Micro angle resolved photoemission spectroscopy resolves a sharp, two dimensional surface resonant state (SRS) that emerges within the CDW reconstructed low energy spectrum. The SRS exhibits notable temperature dependence and its spectral weight collapses around 160 K, while CDW transition temperature TCDW is commonly reported as 202 K. Slab DFT+U calculations reproduce a surface localized resonance when CDW folding brings valence and conduction states into near degeneracy, suggesting a correlation tuned, surface selective origin. These results point to a form of correlation-tuned surface resonance in a layered CDW compound and suggest a framework for engineering low dimensional
quantum states in van der Waals materials via
symmetry breaking and electronic structure tuning.
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All authors Turgut Yilmaz, Yi Sheng Ng, Muhammad Awais Fiaz, Anil Rajapitamahuni, Asish K. Kundu, Shawna M. Hollen, Polina M. Sheverdyaeva, Paolo Moras, Ivana Vobornik, Jun Fujii, Shinichiro Ideta, Kenya Shimada, Boris Sinkovic, Elio Vescovo, Hui-Qiong Wang, Jin-Cheng Zheng
Mesoscale and Nanoscale Physics
Beyond conventional skyrmions in synthetic antiferromagnets
Kayla Fallon, Reshma Peremadathil-Pradeep, Christopher E. A. Barker et al. (+14 more)
Magnetic skyrmions are topologically protected
spin textures that can act as reconfigurable nanoscale information carriers. In synthetic antiferromagnets (SAFs), interlayer exchange coupling offers an additional control parameter beyond the interfacial Dzyaloshinskii-Moriya interaction (DMI) and
magnetic anisotropy. Here, we engineer a SAF composed of two chemically distinct ferromagnets (CoB and CoFeB), in which the external
magnetic field and interlayer exchange act asymmetrically on the sublattices. The competition of these effects, acting as a resultant effective-field, gives rise to two distinct skyrmion families in different field regimes. In large fields, conventional-polarity skyrmions nucleate, with core antiparallel to the external field, whereas in smaller fields an inverse-polarity skyrmion state emerges as the effective-field reverses sign and almost saturates the CoFeB layers. Return-point
memory measurements confirm independent nucleation pathways for the two families. Using element-resolved x-ray magnetometry, correlative
magnetic force and Lorentz transmission electron microscopies, and parameter-matched micromagnetic modelling, we show that all textures reside only in the CoFeB layers, which experience a Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange field originating from the CoB layers. This effective-field method provides a robust route to programmable three-dimensional
spin textures with controlled polarity in selected layers of a multilayer with potential for applications in skyrmion-based computing and
spin-logic architectures.
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All authors Kayla Fallon, Reshma Peremadathil-Pradeep, Christopher E. A. Barker, Zoey Tumbleson, Emily Darwin, Andrea Meo, Eloi Haltz, Benjamin A. Brereton, Trevor Almeida, Colin Kirkbride, Sara Villa, Sophie A. Morley, Mario Carpentieri, Riccardo Tomasello, Hans J. Hug, Christopher H. Marrows, Stephen McVitie
Materials Science
Third-order intrinsic anomalous Hall effect as a transport fingerprint of altermagnets
Longjun Xiang, Hao Jin and Jian Wang
The intrinsic anomalous
Hall effect (IAHE) provides a powerful transport fingerprint of
quantum magnets, with its linear and second-order responses distinguishing ferromagnets and $\mathcal{P}\mathcal{T}$-symmetric antiferromagnets, respectively. Altermagnets, as an emergent class of
quantum magnets, have recently been shown to host a third-order extrinsic anomalous
Hall effect, raising a question of whether an intrinsic counterpart can serve as a diagnostic of altermagnetic order. Based on
spin-group
symmetry analysis, we demonstrate that the third-order IAHE is generically allowed in the ten
spin Laue groups relevant to altermagnets when
spin-orbit coupling (SOC) is taken into account. By combining these
symmetry constraints with the anomalous velocity induced by the second-order Berry
curvature, we uncover a resonant third-order IAHE arising near the altermagnetic band crossings at generic momenta in both the Lieb-
lattice altermagnet and the experimentally realized altermagnet V$_2$Se$_2$O. Notably, we identify the Berry
curvature quadrupole, encoded in the second-order Berry
curvature and activated by finite SOC, as the microscopic
quantum geometric origin of this resonance. Our results establish the third-order IAHE as an intrinsic
quantum geometric transport fingerprint of altermagnets and extend the hierarchy of IAHE across collinear
quantum magnets.
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Mesoscale and Nanoscale Physics
Tunable high-Chern-number Chern insulators in rhombohedral tetralayer graphene/hBN moiré superlattices
Chuanqi Zheng, Chushan Li, Ke Huang et al. (+17 more)
Moiré superlattices based on rhombohedral multilayer
graphene have emerged as a highly tunable platform for engineering correlated topological phases. Here, we systematically investigate the transport properties of the hole-doped side in rhombohedral tetralayer
graphene/ hexagonal boron nitride (hBN) moiré superlattices across a range of twist angles and
alignment orientations. Notably, we observed multiple high-Chern-number Chern
insulators, including the previously reported integer Chern
insulator with Chern number C = -4 at moiré filling factor v = -1 and newly discovered
symmetry-broken Chern insulating states with C = +3, $\pm$2, $\pm$1 at fractional moiré fillings of v = -2.5 or -2.6. These Chern insulating states emerge in both hBN
alignment, but exhibit a sensitive moiré wavelength dependence. Our findings demonstrate the exceptional tunability of these high-Chern-number states via moiré wavelength, displacement electric field and external
magnetic field, underscoring the distinct topological landscape realized in hole-doped RTG/hBN moiré superlattices.
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All authors Chuanqi Zheng, Chushan Li, Ke Huang, Chenyu Zhang, Kenji Watanabe, Takashi Taniguchi, Hao Yang, Dandan Guan, Liang Liu, Shiyong Wang, Yaoyi Li, Hao Zheng, Canhua Liu, Jinfeng Jia, Xueyang Song, Zhiwen Shi, Guorui Chen, Xiao Li, Tingxin Li, Xiaoxue Liu
Materials Science
Revealing magnetism in the distorted kagome $R$Ti$_3$Bi$_4$ ($R$ = Nd, Sm, Gd) via ARPES and XMCD
C. Lim, F. Ballester, A. Kar et al. (+19 more)
Kagome materials are known for hosting emergent
quantum phenomena driven by the interaction between different
lattice, charge and
spin orders. Here, we present a detailed angle resolved photoemission (ARPES), density functional theory (DFT) and x-ray
magnetic circular dichroism (XMCD) study of the electronic and
magnetic structure of $R$Ti$_3$Bi$_4$ ($R$ = Nd, Sm, Gd). ARPES and DFT demonstrate that the bulk electronic band structure is dominated by the hybridization of the Ti bands, and the weak electron-like pocket at $\Gamma$ is identified as a surface state. The isotropic XAS profile of the $M_{4,5}$-edge of the rare earth is consistent with the presence of $R^{3+}$ oxidation state. Using the XMCD sum rules, backed by the atomic multiplet theory calculations, we obtain the
spin and orbital
magnetic moments. The Ti $L_{2,3}$-edge XMCD reveals the presence of a small
magnetic moment in GdTi$_3$Bi$_4$, presumably driven by the proximity of the {Ti} kagome layers to the $zigzag$ chains of Gd, while the total
magnetic moment of Gd is shared by the $f$ and $d$ electrons. Our combined XMCD, ARPES and DFT study brings an important piece of information to understand the
spin flip transitions and anomalous
Hall effect observed in the $R$Ti$_3$Bi$_4$ kagome metals.
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All authors C. Lim, F. Ballester, A. Kar, M. Alkorta, D. Subires, J. Dai, M. Tallarida, E. Vescovo, T. K. Kim, C. Cacho, C. Yi, S. Roychowdhury, A. Kumar Sharma, Y. Choi, G. Fabbris, J. Strempfer, P. Gargiani, C. Shekhar, C. Felser, I. Errea, M. G. Vergniory, S. Blanco-Canosa
Superconductivity
Programmable superconducting diode from nematic domain control in FeSe
R. D. H. Hinlopen, C. Putzke, L. Holeschovsky et al. (+5 more)
The superconducting diode effect (SDE) allows polarity-dependent critical currents when time-reversal and current-inverting spatial
symmetries are broken. Superconducting diodes show promise for applications, but inversion asymmetry is usually encoded in sample geometry or non-centrosymmetric
crystals, rendering them static
circuit elements. Here we demonstrate a programmable superconducting diode whose functionality is encoded in correlated electronic domains. We use the nematic
superconductor FeSe as a platform and report a large intrinsic SDE with efficiencies up to $\eta \sim 75\%$ due to
vortices interacting with nematic twin boundaries. The domain wall configuration thus encodes the SDE of the device. Through intense microsecond current pulses to quench the nematic order at rates exceeding $10^7$ K/s, we modify the domain pattern and control the polarity and strength of the SDE. These results establish a new paradigm in which superconducting
circuit elements can be programmed through patterns imprinted into correlated electronic states.
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All authors R. D. H. Hinlopen, C. Putzke, L. Holeschovsky, R. Nicholls, F. Ronning, E. D. Bauer, N. E. Hussey, P. J. W. Moll
Strongly Correlated Electrons
Electronic structure, quasiparticle renormalizations, and magnetic correlations in the alternating single-layer bilayer nickelate La$_5$Ni$_3$O$_{11}$
I. V. Leonov
Using DFT+DMFT we study the normal-state electronic structure and
magnetic correlations of the recently discovered alternating single-layer
bilayer Raddlesden-Popper nickelate La$_5$Ni$_3$O$_{11}$ (1212-LNO). Our results exhibit qualitative differences for the structurally distinct single-layer and
bilayer Ni ions, implying the importance of confinement and orbital-dependent correlations. The Ni $e_g$ electronic states originating from the
bilayer Ni ions form strongly renormalized quasiparticle bands with a large enhancement factor $m^*/m \sim 3.5$ and 4.2 for the Ni $x^2-y^2$ and $3z^2-r^2$ orbitals, respectively. Moreover, the $e_g$ states of the single-layer Ni ions exhibit an orbital-selective Mott insulating state, with a narrow energy gap for the Ni $3z^2-r^2$ states and metallic, strongly incoherent (non-
Fermi-
liquid) Ni $x^2-y^2$ ones. Our analysis of
magnetic correlations suggests the formation of intertwined
spin and charge density wave stripes in the
bilayer NiO$_6$ slab, in close similarity to the double-layer material. We refine two major instabilities, a leading one is associated with a wave vector ${\bf Q}=(\frac{1}{3},\frac{1}{3})$ (“up-down-0"
spin pattern), competing with the bicollinear $(\frac{1}{4},\frac{1}{4})$ (“up-up-down-down") stripe state. The single-layer Ni $3d$ electrons exhibit instability towards the Néel-type
magnetic state. Under pressure, 1212-LNO undergoes an orbital-selective Mott
insulator-to-metal phase transition, associated with metallization of the single-layer Ni $e_g$ states. As a result, the single-layer Ni $e_g$ bands exhibit non-
Fermi-
liquid (bad metal) behavior with strongly incoherent spectral weights near $E_F$. We note that correlation effects result in a reconstruction of
magnetic correlations as compared to that obtained within DFT. In fact, we observe a crossover from single-layer to double-layer dominated
magnetic correlations.
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Strongly Correlated Electrons
Torsion Induced Asymmetric Luttinger Liquids
Arseny Pantsialei and Nicholas Sedlmayr
We consider a general model of a Luttinger
liquid with broken parity and time reversal
symmetry, but with their composite
symmetry intact. Such a scenario can be due to a combination of torsion and a Zeeman field in nanowires, or a result of bringing different helical Luttinger
liquids into proximity. The broken
symmetries result in a band structure with no axis of
symmetry, and therefore with asymmetric velocities between left and right moving contributions. By taking a general
spin-full model with all possible scattering and interaction terms in the bosonic model we show that generically the
spin degree of freedom becomes gapped out, resulting in an effective spinless Luttinger
liquid with asymmetric velocities. Our work generalizes and extends previous studies which focused on a minimal model of a spinless Luttinger
liquid. We further demonstrate that a possible experimental signature of the asymmetry of such asymmetric models can be seen in the spectral function.
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Statistical Mechanics
Quo vadis, stochastic thermodynamics?
Jan Korbel, Artemy Kolchinsky, Sarah A.M. Loos et al. (+4 more)
Stochastic thermodynamics is a framework for describing non-
equilibrium processes at the level of fluctuating trajectories, where the state of a system evolves as a
stochastic time series, allowing thermodynamic quantities such as work, heat, and
entropy production to be defined along individual realizations rather than at the ensemble level only. Over the past three decades, the field has yielded fundamental results, including fluctuation
theorems and several universal bounds, such as thermodynamic uncertainty relations, speed limit
theorems, and many others. Many of them have been tested on a range of experimental platforms. This Perspective reviews recent developments in
stochastic thermodynamics that extend its scope beyond its traditional domains, including systems with
memory and hidden degrees of freedom, microscopic approaches to interacting and active matter, and
geometric formulations based on optimal transport. Next, the Perspective surveys the challenges that arise when applying these ideas to macroscopic and complex systems, where the link between statistical irreversibility and thermodynamic dissipation becomes less direct. Finally, emerging applications in non-physical contexts are highlighted, including computation, biological systems, and social dynamics. Transcending the traditional boundaries of physics, these developments catalyze an unorthodox framework to tackle the thermodynamics of complex systems.
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All authors Jan Korbel, Artemy Kolchinsky, Sarah A.M. Loos, Gonzalo Manzano, Rosalba Garcia-Millan, Olga Movilla Miangolarra, Édgar Roldán
Disordered Systems and Neural Networks
Effective length scales, dispersion relations, and discrete densities of states for Laplacian eigenvectors on complex networks
Per Arne Rikvold
To construct dispersion relations for
diffusion or oscillation processes on random networks, it is necessary to obtain effective length scales for the eigenvectors of a graph
Laplacian matrix, whose
eigenvalues represent inverse time scales. For this purpose, we adapt a method originally introduced in condensed-matter physics to estimate correlation lengths for disordered materials as the ratio of volume to interface area [P. Debye, H.R. Anderson and H. Brumberger, J. Appl. Phys. 28, 679 (1957)]. In a graph setting of vertices connected by edges, we interpret this as the ratio of twice the total number of edges to the number of edges connecting vertices bearing values of different sign on the particular eigenvector. After describing the method and the necessary concepts in pedagogical detail, we apply it to nine different graphs representing natural and artificial networks, including two tree graphs without and with random shortcuts, the nervous system of a roundworm, a food web, a social network of dolphins, an electrical power grid, and a model porous material. The results identify both distributed and localized eigenvectors. They are given in graphical format showing example eigenvectors, dispersion relations, and discrete densities of states, as well as tables summarizing the main numerical results.
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Statistical Mechanics · Cross-listed from q-bio.PE
Dispersal diversity buffers species vulnerability to local extinction
Davide Bernardi, Giorgio Nicoletti, Prajwal Padmanabha et al. (+5 more)
Predicting species persistence within ecological communities is a fundamental challenge for both empirical and theoretical ecology. Existing methods span from mechanistic models, whose parameters are difficult to estimate from data, to statistical tools whose context-specific parameters are less interpretable. Here, we present a general framework, grounded in the statistical physics of complex systems, that integrates the key processes governing species survival into a single measurable quantity: the competitive balance. This metric quantifies a focal species' vulnerability to competitive exclusion beyond what is captured by its abundance alone by incorporating the diversity of dispersal strategies and the structure of interspecific interactions within the community. Crucially, it can be inferred from spatial abundance data, thus circumventing the need to estimate species traits or dispersal parameters. Our results reveal that greater heterogeneity in dispersal strategies reduces vulnerability to competitive exclusion for a given abundance. Although we validate the framework using tropical and temperate forest data, it can be applied to a range of different ecosystems, providing a systemic and interpretable tool for assessing a context-dependent species vulnerability that accounts for its interactions with the entire community.
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All authors Davide Bernardi, Giorgio Nicoletti, Prajwal Padmanabha, Samir Suweis, Sandro Azaele, Simon A. Levin, Andrea Rinaldo, Amos Maritan
Mesoscale and Nanoscale Physics
Flux-Mediated Correspondence Between Real- and Momentum-Space Nonsymmorphicity
Z. Y. Chen and Y. X. Zhao
Momentum-space nonsymmorphic
symmetries have recently attracted significant interest in both artificial and condensed-matter
crystals, whereas real-space nonsymmorphic
symmetries have long played an important role in the study of crystalline topological phases. Here, we establish a general theory of momentum-space crystallographic groups that emerge from projective representations of real-space crystallographic groups in the presence of gauge flux, applicable in particular to real-space nonsymmorphic groups. A central result is a flux-mediated “bi-nonsymmorphicity” relation that reveals a structural correspondence between real-space and momentum-space nonsymmorphicity mediated by gauge flux. This relation implies that, under a symmetric gauge flux, real-space nonsymmorphicity can enforce momentum-space nonsymmorphicity, and that in some cases a symmetric gauge flux requires nonsymmorphicity in both real and momentum space. Our work not only identifies a fundamental structure in projective
crystal symmetries, but also provides guiding principles for designing artificial
crystals and condensed-matter platforms that exhibit both real-space and momentum-space nonsymmorphic
symmetries.
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Statistical Mechanics · Cross-listed from quant-ph
Reservoir-mediated spin entanglement in the mean-force Gibbs state
L. A. Williamson, W. McEniery, F. Cerisola et al. (+1 more)
Two
qubits strongly coupled to a common bosonic reservoir can become entangled with each other, despite having no direct interaction. In
equilibrium, such coupling-induced coherences can be described by the mean-force Gibbs state. Here we derive approximate, analytic expressions for the two-
qubit mean-force Gibbs state, and use these to characterize
equilibrium qubit-
qubit entanglement mediated by a thermal reservoir.
Entanglement, which is highest at lowest temperatures, is a non-monotonic function of the system-reservoir coupling strength. Moreover, we find that broadening the reservoir spectral density beyond a single mode, as is realistic for typical baths, can enhance the
qubit entanglement. Our results provide a comprehensive understanding of reservoir-mediated two-
qubit entanglement in thermal
equilibrium and provide a
benchmark to compare with numerical methods, as well as demonstrating the utility of strong system-reservoir coupling as a resource.
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All authors L. A. Williamson, W. McEniery, F. Cerisola, J. Anders
Materials Science
Unraveling the symmetry of Al5C3N
Vitalii Shtender, Chin Shen Ong, Pedro Berastegui et al. (+6 more)
The high-temperature ceramic compound Al5C3N with promising application usage belongs to the scarcely studied Al-C-N system. It was originally reported as an ordered compound in the non-centrosymmetric space group P63mc and described as a nanolaminate with an -Al2C-AlN-Al2C2- stacking sequence. The recently reported structural disorder in the related compound Al4SiC4 led us to question this proposed structure for Al5C3N and investigate the possibility of a disordered structure in the centrosymmetric space group P63/mmc. In the present work, we employed different synthesis routes to maximize the yield and quality of the desired phase, and applied a variety of techniques to probe the Al5C3N
crystal structure. Our single-
crystal X-ray diffraction analysis clearly indicates that the non-centrosymmetric space group P63mc must be rejected. From a joint refinement of single-
crystal X-ray and powder
neutron diffraction data, the occupancies of C and N were refined at two sites in P63/mmc resulting in the stacking sequence -Al2C-Al(C/N)-Al2(C/N)2-. Furthermore, DFT calculations show that a centrosymmetric disordered structure described in a supercell has the lowest energy, 0.2 eV per formula unit, relative to the previously reported P63mc structure. The calculated band structure shows both direct and indirect band gaps which lead to implications for the physical properties. Finally, STEM analysis provides additional evidence that the
crystal structure of Al5C3N is better described in the centrosymmetric space group P63/mmc.
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All authors Vitalii Shtender, Chin Shen Ong, Pedro Berastegui, Olivier Donzel-Gargand, Johan Cedervall, Charles Hervoches, Premek Beran, Olle Eriksson, Ulf Jansson
Materials Science
AIM2DAT: A Python-based Automated Ab Initio Material Modeling and Data Analysis Toolkit
Holger-Dietrich Saßnick, Joshua Edzards, Timo Reents et al. (+1 more)
The emergence of data-driven computational materials science offers unprecedented opportunities to explore complex material landscapes, complementing experimental research with the discovery of novel compounds. To enable these developments, it is essential to establish robust, reliable, and easy-to-use software supporting workflow automation and large
dataset processing. Herein, we introduce the Automated Ab Initio Materials Modeling and Data Analysis Toolkit (aim2dat), a Python package offering a user-friendly interface to generate and handle big data, design high-throughput workflows based on density functional theory calculations, and analyze the output. Its key features include interfaces to online databases for structure query and analysis, high-throughput screening routines, and seamless integration of machine learning models. The capabilities of aim2dat are showcased with a variety of use-cases, ranging from photocathode materials to metal-organic frameworks.
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All authors Holger-Dietrich Saßnick, Joshua Edzards, Timo Reents, Caterina Cocchi
Materials Science · Cross-listed from physics.chem-ph
Physics-based modeling of cyclic and calendar aging of LIBs with Si-Gr composite anodes
Micha C. J. Philipp, Lukas Köbbing, Alexander Karger et al. (+3 more)
Higher energy density and longer lifetime are the requirements for next-generation lithium-ion batteries. A promising anode material is silicon, which offers high specific capacity, but its significant volume change during lithiation and delithiation enormously reduces battery lifetime. A physical understanding of the processes degrading the battery is key to mitigate this effect and advance in the field. We develop a physics-based model to describe degradation during battery cycling under various protocols and storage conditions, with varying check-up (CU) frequencies. The model can disentangle basic degradation mechanisms, such as the growth of the Solid-Electrolyte Interphase (SEI), from silicon mechanisms, such as particle cracking, SEI growth on cracks, and loss of active material (LAM). We investigate the impact of CUs on the observed storage degradation and the reason behind the increased degradation in batteries, including silicon in the anode. Additionally, we relate the observed degradation to operating conditions, enabling future optimization of battery use and design.
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All authors Micha C. J. Philipp, Lukas Köbbing, Alexander Karger, Andreas Jossen, Arnulf Latz, Birger Horstmann
Quantum Gases
Phases and dynamics of an impurity immersed in one-dimensional quantum droplets
Dimitrios Diplaris, Ilias A. Englezos, Friethjof Theel et al. (+2 more)
We explore the ground-state properties of a single
impurity immersed in a one-dimensional
quantum droplet medium formed by a two-component Bose mixture. Relying on ab-initio simulations, we demonstrate that tuning the
impurity-droplet interactions allows to controllably reshape the droplets density profiles and associated correlation patterns. For attractive
impurity-medium couplings, the
impurity becomes localized within the droplet which exhibits a density hump at the vicinity of the
impurity, while repulsive interactions facilitate their phase-separation. Comparing our many-body results to the appropriate extended Gross-Pitaevskii description, we find adequate agreement for the droplet density profiles, with the effective field approach systematically overestimating
impurity localization. Following a release of the external trap, we unveil that the sign and magnitude of the interactions between the
impurity and the droplet hosts dictate the response of the three-component setting which experiences expansion unless strongly attractive intercomponent couplings are present. These results corroborate the role and presence of correlations in
impurity-droplet mixtures and inspire future investigations on
impurity physics for probing droplet configurations.
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All authors Dimitrios Diplaris, Ilias A. Englezos, Friethjof Theel, Peter Schmelcher, Simeon I. Mistakidis