Materials Science
Reducing the Gate-Induced Drain-Leakage Current of Carbon-Nanotube Transistors by Subliming Dispersants with Back-End-of-Line Compatible Temperature
Takumi Inaba, Yuichi Kato, Yoko Iizumi et al. (+4 more)
Carbon nanotube field-effect transistors (CNTFETs) are promising for monolithic 3D integration with silicon CMOS
circuits in back-end-of-line (BEOL) processes. Further reduction in off-state leakage is essential for practical applications. In this study, we develop a low-temperature cleaning process for CNT-deposited wafers using a sublimable CNT dispersant. The process is carried out below 250 {\deg}C, making it BEOL-compatible, and does not deteriorate CNT morphology or
lattice structure, as confirmed by atomic force microscopy and Raman spectroscopy. As a result, gate-induced drain leakage current originating from residual dispersants is reduced by approximately one order of magnitude. In addition, improvements in on-current, subthreshold slope, and threshold voltage variability are observed after the cleaning process. This study demonstrates a material-enabled approach to improve the transfer characteristics of CNTFETs and provides a practical route toward low-power CNT electronics.
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All authors Takumi Inaba, Yuichi Kato, Yoko Iizumi, Yasuhiko Fujita, Kazufumi Kobashi, Takahiro Morimoto, Toshiya Okazaki
Superconductivity
Disorder-driven transport in ZrN thin films grown by ion-beam-assisted sputtering
Maximo DiPreta, Samuel Jiang, Serhii Kruhlov et al. (+3 more)
We investigate the structural and electronic transport properties of zirconium nitride (ZrN) thin films grown by dc ion-beam assisted sputtering (IBAS) as a function of nitrogen partial pressure, sputtering power and deposition temperature. Variation of growth conditions enables controlled tuning from disordered metallic and superconducting behavior to insulating transport. Increasing nitrogen flow drives an increase in sheet resistance, suppression of superconducting transition temperature, and non-metallic conduction. XRD shows no measurable change in long range crystallinity or order. In the insulating regime, low-temperature transport is well described by 3D Mott variable-range hopping (VRH), with the characteristic temperature $T_0$ increasing monotonically with sheet resistance over four orders of magnitude. Despite this strong correlation between $T_0$ and disorder, $T_c$ exhibits no systematic dependence on $T_0$, indicating a decoupling between localization physics and the superconducting energy scale. Magnetotransport measurements are not well described by the standard BCS model nor the dirty type-II Werthamer-Helfand-Hohenberg model. The phase boundary is instead captured by a free-exponent power law, $\mu_0 H_{c2}(T) = \mu_0 H_{c2}(0)[1 - (T/T_c)^{n}]$ with $n \approx 3.47$, and extrapolates to $\mu_0 H_{c2}(0) \approx 6.4$ T. The films have an extracted coherence length of 7 nm. These results establish IBAS-grown ZrN as a broadly tunable platform for investigating disorder-driven transport and the crossover between metallic conduction, electronic localization, and superconductivity.
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All authors Maximo DiPreta, Samuel Jiang, Serhii Kruhlov, Yi Li, Valentine Novosad, Tomas Polakovic
Strongly Correlated Electrons · Cross-listed from quant-ph
An entropic characterization of Haag duality
Ruizhi Liu and Lauritz van Luijk
Motivated by Haag duality in
quantum spin systems, we show that Haag duality for a pair of commuting factors generated by increasing sequences of finite-dimensional
matrix algebras is equivalent to the asymptotic vanishing of a suitable conditional mutual information. For
spin systems, let an annulus separate a finite region from the exterior. Haag duality then holds for a region $A$ if and only if the mutual information of the inner region and the exterior, conditioned on the part of $A$ inside the annulus, vanishes as the outer radius becomes large. As a corollary, assuming a strict area law with subleading corrections, Haag duality holds for single cones, and it holds for unions of two or more disjoint cones precisely when the topological
entanglement entropy vanishes. For translation-invariant pure states on
spin chains, half-chain Haag duality is equivalent to vanishing
entropy density.
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Materials Science
Local Response Theory of Electrified Interfaces from Screened Effective Charges
Nicolas G. Hörmann, Nicolas Bergmann and Karsten Reuter
First-principles, electronic-structure simulations provide direct access to ground-state, global system properties. In the context of computational electrochemistry these are, e.g., bias-dependent energies, free energies, work functions, and capacitances. However, a comparably systematic local description of how these quantities respond to biasing via interfacial charging is still missing. Here, we introduce the screened electrochemical Born effective charge (SEBEC), a mixed total-energy derivative that measures the force response of an atomic degree of freedom to interfacial charging under electrochemical boundary conditions. SEBECs play the role for electrochemistry that Born effective charges play in the modern theory of polarization: they provide an unambiguous decomposition of global response and generate the same formal structures for structural relaxation, capacitance, and electrochemical Stark tuning that are familiar from solid-state response theory. The broader implication is a local response framework that brings electrochemical interfaces closer to the conceptual rigor long established for insulating solids.
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Materials Science
Slow Thermalization and Long-Lived Coherence across Acoustic Phonon Branches in BAs
Zeyu Xiang, Ying Peng, Ange Benise Niyikiza et al. (+11 more)
The exceptionally high thermal conductivity of cubic boron arsenide (BAs) arises from suppressed three-
phonon scattering associated with its large acoustic–optical gap. In this regime, four-
phonon processes become non-negligible, creating an unusual scattering hierarchy with unexplored consequences for nonequilibrium
phonon dynamics. Here, time-resolved x-ray diffuse scattering reveals exceptionally slow, branch-dependent acoustic
phonon thermalization and long-lived coherence. Exploiting branch sensitivity in one-
phonon diffuse scattering, we resolve transverse acoustic (TA) and longitudinal acoustic (LA) thermalization times of 29.2 and 13.9~ps, respectively; even the LA timescale is at least three times that in common
semiconductors.
Phonon dispersion calculations assign coherent oscillations at 0.19 and 0.27~THz to the TA and LA modes, respectively; both persist with little decay over 50~ps, with comparable coherence found only in diamond. These findings provide a direct dynamical manifestation of the weak
phonon scattering underlying the exceptional thermal transport of BAs.
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All authors Zeyu Xiang, Ying Peng, Ange Benise Niyikiza, Fanghao Zhang, Haoyuan Li, Takahiro Sato, Thomas Linker, Yanwen Sun, Meredith Henstridge, Vincent Esposito, James F. Cotter, Diling Zhu, Zhifeng Ren, Bolin Liao
Materials Science
Non-reactive sintering enhances density and ionic conductivity of NASICON solid electrolytes
Andrea Cornelio, Björn Mieller, Johannes Baller et al. (+6 more)
NASICON materials are promising solid electrolytes for room-temperature sodium solid-state batteries and are typically synthesized via solid-state reaction. While sintering has been extensively studied, the effect of calcination on electrolyte properties remains poorly understood. In this work, the temperatures at which the NASICON phase forms in Na3Zr2Si2PO12 and Na3.4Zr2Si2.4P0.6O12 are identified. Calcination temperature is then varied between 900 {\deg}C and 1200 {\deg}C to obtain powders with different degrees of reaction prior to sintering. Under identical sintering conditions, higher NASICON phase content in the calcined powder is shown to yield denser electrolytes. Non-reactive sintering also improves grain boundary conductivity, increasing it by 130% for Na3.4Zr2Si2.4P0.6O12 and raising total conductivity from 1.60 to 2.95 mS/cm for powders calcined at 900 {\deg}C and 1200 {\deg}C, respectively. Finally, it is shown that phosphorus loss during processing compromises cycling stability against Na metal electrodes, and that adding off-stoichiometric phosphorus resolves this issue, while reaching a critical current density of 5.0 mA/cm^2 and a room-temperature conductivity of 3.82 mS/cm with over 400 hours of stable cycling. Overall, these findings directly relate synthesis and processing conditions to the final material properties and electrochemical performance of NASICON solid electrolytes.
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All authors Andrea Cornelio, Björn Mieller, Johannes Baller, Andrea Fantin, Janina Roik, Jessica Kindt, Jonas Krug von Nidda, Tim-Patrick Fellinger, Gustav Graeber
Quantum Gases
Scaling equations for Bose-Einstein condensate dynamics across all interaction regimes
D. C. Marinica, C. Puertas González, T. Estrampes et al. (+5 more)
We derive a unified set of scaling equations for Bose-Einstein condensates in time-dependent harmonic traps, connecting the weakly interacting Gaussian regime to the strongly interacting Thomas-Fermi regime. The exact Gross-Pitaevskii ground-state density is taken as a fixed profile in rescaled coordinates, with its dynamics described by three scaling factors corresponding to compression or expansion along the three spatial directions. The resulting equations contain no adjustable parameter, since their coefficients are determined once from the initial state. They recover analytically the Gaussian variational and Thomas-Fermi scaling equations in their respective limits and satisfy an axis-resolved virial
theorem. The approach also yields the global phase and the low-lying collective-mode frequencies of the condensate. We
benchmark the model against three-dimensional Gross-Pitaevskii simulations and against measured expansion energies. The model remains accurate across all interaction regimes, in strongly anisotropic traps, and along time-dependent sequences including a relatively fast quench, up to the point where the underlying frozen-profile hypothesis, shared by all three scaling approaches, breaks down.
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All authors D. C. Marinica, C. Puertas González, T. Estrampes, A. Herbst, D. Schlippert, E. M. Rasel, N. Gaaloul, E. Charron
Soft Condensed Matter
Liquid-Phase Near-Field Infrared Nanoscopy of Ion-Exchange Reactions
Wassie M. Takele, Teferi Sitotaw Yallew, Mason Caron et al. (+1 more)
In situ monitoring of reactions with chemical specificity and nanometer-scale spatial resolution under aqueous conditions remains a long-standing experimental challenge. Here, we use thin SiC membrane-enabled
liquid-phase infrared nanoimaging and nanospectroscopy to monitor Ca$^{2+}$/Na$^{+}$ ion exchange in a mixture of disodium terephthalate and CaCl$_2$ solution. Beneath the membrane, we follow the formation of calcium terephthalate (CaTP), a metal-organic framework (MOF)-type coordination phase in which terephthalate ligands link Ca$^{2+}$ centers. The symmetric and asymmetric carboxylate stretching modes serve as chemically specific near-field reporters of Ca$^{2+}$ coordination to the terephthalate linkers. Nano-FTIR spectra reveal pronounced peak shifts and linewidth changes in these vibrational modes, indicating modification of the carboxylate coordination environment during CaTP formation. Complementary near-field nanoimaging resolves the emergence of nanoscale precipitates beneath the SiC membrane following CaCl$_2$ injection, providing spatially resolved evidence of the formation of the CaTP coordination framework. Solid-phase nanoimaging and nanospectroscopy identify well-defined CaTP particles, providing further evidence for crystalline CaTP formation. We demonstrate that the chemistry of metal-ligand interactions can be monitored in situ via
liquid-phase near-field nanoscopy. This capability could enable the study of catalytic, electrochemical, and biological processes under native aqueous conditions.
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All authors Wassie M. Takele, Teferi Sitotaw Yallew, Mason Caron, Yohannes Abate
Materials Science · Cross-listed from physics.optics
Transverse-Anderson localization of light in disordered silicon pores
S. Erfanifam, C. Yanik and M. Erfanifam
Transverse light localization of Anderson type through disorders has made intriguing fundamental topics. Toward this, we found that in the disordered porous Si (PSi) a nearly "zero reflection" (from 450 to 900 nm) can be observed. The localization length versus disorder parameter is experimentally visualized and calculated based on a self consistent theory and solution of
stochastic Helmholtz equation for electric fields traveling in a transverse disordered media with the results determined to be in a reasonable agreement with experiments. Based on these calculations for different pore diameters in a constant order parameter,
diffusion length can vary from 260 nm to 2.4\mu m, accounting as controllability of such structure for further applications in photonic devices. Reflection from ordered PSi structure are evaluated that shows no similar responses to those seen in disordered PSi.
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Other Condensed Matter
Magnon Theory of Domain Wall Wavefronts and the Ballistic Diffusive Crossover in the Classical Anisotropic Landau Lifshitz Spin Chain
Akash Sarkar
We study the far-from-
equilibrium dynamics of domain-wall initial states in the integrable
lattice Landau–Lifshitz
spin chain. Building on the linear
spin-wave description of domain-wall spreading, we derive the long-wavelength
magnon dispersion directly from the microscopic integrable
Hamiltonian and use it to characterize the propagation and broadening of the resulting wavefronts. The dispersion interpolates between a quadratic form at the isotropic point and a linear form in the easy-plane regime. In the isotropic limit, the quadratic dispersion leads to diffusive broadening, whereas in the easy-plane regime the domain-wall front propagates ballistically. Keeping the leading nonlinear correction to the linear dispersion gives a cubic dispersive term, which produces a characteristic $t^{1/3}$ broadening of the ballistic front. We further show that the sign of this cubic correction changes at a critical anisotropy, leading to a reversal of the dispersive wake from trailing to advancing. The resulting critical point occurs at $\Delta_c=1/7$, corresponding to $\gamma_c\simeq 1.047$. Numerical simulations of the full nonlinear
spin dynamics confirm the analytical scaling and demonstrate the coexistence of the amplitude-independent
spin-wave front with amplitude-dependent nonlinear
soliton propagation.
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Soft Condensed Matter
Local Strain-Dependent Anisotropy in Fibrous Networks
Yoni Koren, Shahar Goren, Oren Tchaicheeyan et al. (+1 more)
Cells in connective tissues reside within the extracellular
matrix (ECM), which consists of a fibrous mesh that exhibits non-linear strain-stiffening behavior, driven by a transition from bending-to-stretching-dominated deformation. While bulk rheology captures macroscopic mechanical properties,
cells actively sense and respond to local microscale heterogeneities and stiffness anisotropy in their environment. Characterizing ECM micromechanics is therefore essential for understanding the mechanical cues experienced by
cells. This study quantifies local stiffness anisotropy in stretched fibrous gels by combining experimental and numerical approaches. Experimentally, we utilized optical tweezers microrheology to measure local stiffness in fibrin gels subjected to uniaxial stretch. The gels demonstrated gradual local stiffening along both the tensile and perpendicular axes, with a more profound increase along the tensile axis, resulting in local anisotropy. To investigate the physical parameters driving this phenomenon, we developed a 3D finite element model of a discrete random fiber network, successfully replicating the experimental local stiffening and anisotropy. Numerical analysis further revealed that within the sub-isostatic region, both fiber thickness and network connectivity strongly influence local anisotropy: slender fibers and higher connectivity amplify the anisotropy by up to an order of magnitude. This contributes to the formation of a highly anisotropic local environment, thereby playing a significant role in directing mechanically driven biological processes, such as
cell migration and durotaxis. Our simulations also indicate that local micromechanical responses may differ from the material's global stiffening behaviors, highlighting the need for characterization at the microscopic scale.
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All authors Yoni Koren, Shahar Goren, Oren Tchaicheeyan, Ayelet Lesman
Materials Science
Symmetry- and Property-Aware Crystal Generation with Reinforcement Learning for Inverse Materials Design
Ting-Wei Hsu, Arun Bansil and Qimin Yan
The inverse design of crystalline materials ultimately seeks structures with desired physical properties. However, for many functional responses, a favorable numerical value is meaningful only when supported by the
symmetry of the underlying
crystal. Without the appropriate crystallographic constraints, an apparent response may be ill defined, accidental, or not
symmetry protected. Here we introduce SPARC, a
symmetry- and property-aware reinforcement learning framework that optimizes physical objectives while preserving the structural conditions required for their realization. We demonstrate SPARC on two complementary tasks. The first targets strong uniaxial dielectric anisotropy, a tensorial response that is well defined only within appropriate
crystal classes. The second maximizes the spectroscopic limited maximum efficiency, a scalar device-level objective without a prescribed
symmetry class, allowing the framework to identify favorable crystallographic motifs. These results show that
symmetry is not merely an additional design constraint, but a physical foundation for generating candidates with meaningful, robust, and realizable functional properties.
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Materials Science
Particle Inertia-Driven Pore Formation over Material Property Effects in Laser Powder-blown Directed Energy Deposition
Dong Hee Kang, Samantha Webster, Sampson Canacoo et al. (+3 more)
Laser Powder-blown Directed Energy Deposition (LP-DED) offers flexibility for process and materials and high productivity (~5 kg/h), but process-induced pores often compromise mechanical properties. This study utilizes in-situ X-ray synchrotron imaging to compare pore formation mechanisms in Ti-6Al-4V (Ti64) and stainless steel 316L (SS316L), focusing on the interplay between particle dynamics and thermophysical properties. Four distinct pore formation mechanisms were identified, with most large pores originating from the closure of cavities formed behind incident particles impinging on the melt pool. High Weber number (We >> 1) governs this behavior, indicating that particle inertia, rather than thermophysical property differences, is the primary driver of large pore formation. The study demonstrates that increased energy density leads to larger melt pool volumes, facilitating deeper particle penetration. This greater penetration depth directly correlates with increased pore diameters. While thermophysical properties secondarily influence pore-formation frequency and cavity
symmetry, particle inertia remains the dominant factor. These findings provide a physically grounded basis for understanding and controlling porosity in powder-blown DED processes.
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All authors Dong Hee Kang, Samantha Webster, Sampson Canacoo, Samuel J. Clark, Kamel Fezzaa, Jihoon Jeong
Materials Science
Cracking the case: fluctuations enhance ductility in refractory alloys
Manura Liyanage, Julia Chmielewska, Tijmen Vermeij et al. (+4 more)
Refractory body-centered cubic (BCC)
alloys are attractive candidates for structural applications at extreme temperatures, yet combining room-temperature ductility with high-temperature strength remains the unsolved challenge. Ductility in
crystals requires that dislocations emit from a sharp crack tip before brittle cleavage, but continuum theories that treat disordered
alloys as chemically homogeneous incorrectly predict brittleness for many experimentally ductile
alloys. Here we show that atomic-scale stress fluctuations in disordered
alloys create an additional local stress intensity at the crack tip, enabling dislocation loop nucleation below the cleavage threshold. Accounting for these fluctuations yields a local ductility criterion where
alloys deemed brittle by conventional fracture mechanics can be intrinsically ductile. Atomistic simulations with machine-learned interatomic potentials and an analytic fracture mechanics model correctly predict composition-driven brittle-to-ductile transitions in binary and ternary Mo-Nb-Ti
alloys, in Nb-Ti
alloys at 4 K, and in several commercial BCC
alloys at room temperature. Guided by this criterion, we predict, fabricate, and test the Hf$_{15}$Mo$_{15}$Nb$_{32}$Ti$_{38}$
alloy, confirming its room-temperature ductility. This fluctuation-driven mechanism provides a quantitative basis for designing ductile multicomponent BCC
alloys.
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All authors Manura Liyanage, Julia Chmielewska, Tijmen Vermeij, Johann Michler, Christian Leinenbach, W. A. Curtin, Anirudh Raju Natarajan
Disordered Systems and Neural Networks
Fuzzy Erdos-Renyi random graphs: Spectral statistics
J. A. Mendez-Bermudez
Within a random-
matrix-theory (RMT) approach, we perform a detailed numerical study of the spectral statistics of fuzzy Erdos-Renyi (ER) random graphs. Specifically, we consider the membership values of the vertices and edges of a fuzzy ER graph model as random variables. In this way, the corresponding adjacency
matrices become sparse
matrices with random entries. Then, we apply standard RMT measures to characterize the
eigenvalues and eigenvectors of ensembles of Hermitian and non-Hermitian adjacency
matrices of both undirected and directed fuzzy graphs. We demonstrate that the average degree of the ER model serves as the scaling parameter of the spectral properties of the corresponding fuzzy setups.
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Materials Science
Precessional modes of phonon angular momentum
Daniel A. Bustamante Lopez and Dominik M. Juraschek
Magnons are collective precessional excitations of electron
spins and are ubiquitous in emerging information technologies. Here, we show that the
crystal lattice can support an analogous precessional mode of
phonon angular momentum. Superposition of a circularly polarized
phonon and a linearly polarized
phonon normal to the circular-motion plane generates a transverse angular-momentum component that rotates at their difference frequency and decays on a timescale set by the participating
phonon linewidths, defining a mode with its own resonance and lifetime. Coupling between
spin and
phonon angular momentum hybridizes this precessional mode with a
magnon near resonance. Our results establish
phonon angular momentum precessional modes as
lattice analogues of
magnons and identify their spectroscopic and time-domain signatures.
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Superconductivity
Spatial instability of a homogeneous superconductor after an interaction quench
Medha Roy Choudhury, Sankha Subhra Bakshi, Pinaki Majumdar et al. (+1 more)
We investigate the
quantum dynamics of a conventional
superconductor, described by the attrac- tive Hubbard model, driven far from
equilibrium by quenching the Hubbard attraction. We evolve the full density
matrix of the system in time using the Heisenberg equation of motion, tracking the spatiotemporal dynamics of the pairing and density fields. We use very weakly inhomogeneous initial conditions to probe the stability of the homogeneous dynamics to spatial perturbations. At initial times after the quench the pairing and density fields remain homogeneous in space while fluctuating in time. However, depending on the quench strength the spatially uniform dynamics can become unstable beyond a threshold time, with emergence of spatial textures. The onset time for the instability depends on the strength of the quench and the initial inhomogeneity. At long times the system evolves towards a state with significantly reduced spatial heterogeneity. The time dependence of the global superconducting order parameter suggests two broad categories of re- sponse to a quench. One of these involves strongly inhomogeneous pairing and bond currents in the nonequilibrium
superconductor.
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All authors Medha Roy Choudhury, Sankha Subhra Bakshi, Pinaki Majumdar, Amit Ghosal
Strongly Correlated Electrons
Tripartite entanglement in chaotic eigenstates
Junjia Zhang, Ramanjit Sohal and Shinsei Ryu
It is now well-established that classical statistical mechanics emerges from the
entanglement structure of
quantum chaotic systems, as quantified by the (subsystem) eigenstate thermalization hypothesis (ETH). While this statement rests on the well-studied bipartite
entanglement of the eigenstates of such systems, recent years have shown that many-body states are often characterized by multipartite
entanglement, raising the question: what are the universal multipartite
entanglement features of chaotic eigenstates? We answer this question in part by studying a tripartite generalization of the ergodic bipartition ansatz through the lens of two tripartite
entanglement probes, the Rényi tripartite multi-
entropy and the Rényi reflected
entropy. We derive leading-order analytical expressions for the ensemble averages of both quantities using a saddle-point analysis. Beyond these measures, we obtain the average of the Rényi-2 reflected density
matrix, $\rho_{AA^*}^{(2)}$,which controls the Rényi-2 reflected
entropy. We show that $\rho_{AA^*}^{(2)}$ in a chaotic eigenstate is well-described by this ensemble average which, unlike an ordinary reduced density
matrix, takes three qualitatively distinct forms across subsystem-size regimes, which may be viewed as a tripartite generalization of subsystem ETH. We
benchmark our analytical predictions against exact diagonalization of the mixed-field Ising model.
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Soft Condensed Matter
Biaxial nematics and nematic-nematic demixing in polydisperse mixtures of hard board-like particle fluids
Yuri Martinez-Raton, Daniel de las Heras and Enrique Velasco
We study the bulk phase behavior of a polydisperse
liquid crystal fluid made of biaxial boards with restricted orientations using both fundamental measure theory and Monte Carlo computer simulations. The continuous polydispersity is included in the intermediate particle length of the boards via a truncated Schulz distribution. By calculating several phase diagrams across a range of polydispersity coefficients, we find that polydispersity (i) enhances demixing between two uniaxial nematic phases and (ii) expands the stability region of the biaxial phase. Although metastable with respect to non-uniform phases, we identify certain mixtures exhibiting two-phase coexistence paths involving uniaxial-uniaxial and uniaxial-biaxial phase separations. Whether these paths can be completed depends on the precise shape of the parent distribution function. Monte Carlo simulations performed for a representative case exhibit the same phase diagram
topology predicted by theory, thereby validating the theoretical approach. The main difference between both approaches lies in quantitative agreement, with simulated phase transitions systematically occurring at higher packing fractions than those predicted theoretically. Our combined theoretical and simulation results may prove relevant to the design and interpretation of sedimentation experiments on colloidal suspensions of polydisperse anisotropic particles.
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Superconductivity
Michael Liudeng, Hrishikesh Patel, Marcel Franz et al. (+1 more)
Fully gapped
spin-triplet
superconductors offer a natural setting for topological edge transport and Majorana excitations. Here we propose a
heterostructure that interfaces altermagnetic monolayer V$_2$Se$_2$O with a conventional $s$-wave
superconductor. Starting from an ab-initio description of V$_2$Se$_2$O, we construct a low-energy model of its
spin-split Fermi surface and study the superconducting instability of the coupled stack. We find that the momentum-dependent exchange splitting of the altermagnet strongly favors equal-
spin pairing and converts the proximity-induced order into a fully gapped $p$-wave state. Over a broad range of interface parameters, the resulting Bogoliubov-de Gennes bands carry a nonzero Chern number, and slab spectra exhibit chiral Majorana edge modes traversing the bulk gap. We further quantify the inverse proximity effect and show how the induced gap evolves across a finite multilayer stack. These results establish a route to topological triplet superconductivity by interfacing a conventional
superconductor with an experimentally available altermagnetic
semiconductor, and provide practical guidance for interface fabrication and experimental detection.
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All authors Michael Liudeng, Hrishikesh Patel, Marcel Franz, Niclas Heinsdorf
Superconductivity
Superconducting Diode Effect in Josephson $\varphi_0$ Junction
A. Janalizadeh, Y. M. Shukrinov and M. R. Kolahchi
We investigate the superconducting diode effect in a Josephson junction with a ferromagnetic weak link in the presence of Rashba
spin-orbit coupling. While the standard $\varphi_0$ junction model is valid only for weak exchange fields $h \lesssim T_c$, realistic ferromagnetic barriers typically operate in the regime $h \gg T_c$, where the conventional Ginzburg-Landau gradient expansion becomes insufficient and requires the inclusion of higher order gradient terms to ensure stability of the free energy. By extending the free energy with such higher order term, we demonstrate that the linear gradient coupling alone leads to finite momentum Cooper pairing while leaving the critical current
symmetry unchanged. The interplay between this linear term and the higher order gradient one leads to the Josephson diode effect.
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Materials Science
Visualizing impurity-driven scattering phase textures in EuCd2As2
Raquel Sánchez-Barquilla, Rafael Pineda Medina, Pablo García Talavera et al. (+11 more)
Understanding how disorder modifies electronic states in
magnetic semiconductors is important for controlling
spin-dependent transport and topological responses. Here we use scanning tunneling microscopy to visualize scattering phase textures in EuCd2As2. By isolating a single surface wavevector we reconstruct spatial phase maps of the local density of states and identify phase dislocations characterized by 2pi winding around impurity sites. These phase singularities emerge systematically within charge puddles generated by Eu interstitials and their positions evolve with bias voltage. We show that their spatial structure is consistent with interference between multiple scattering channels, including contributions from
spin-orbit coupling. We provide a model which reproduces phase dislocations and relates the decay of the phase gradient to the relative strength of
spin-orbit and scalar scattering. Our results establish a route to access the phase of electronic scattering in real space and study the role of local disorder and
spin-orbit interactions in shaping electronic states in
quantum materials.
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All authors Raquel Sánchez-Barquilla, Rafael Pineda Medina, Pablo García Talavera, Adrian Valadkhani, Edwin Herrera, Brinda Kuthanazhi, Lin-Lin Wang, Sergey L. Bud'ko, Paul C. Canfield, Roser Valentí, Isabel Guillamón, William J. Herrera, Alfredo Levy Yeyati, Hermann Suderow
Strongly Correlated Electrons
Effective theory of the hidden-order pseudogap phase in a doped antiferromagnet
Gaia De Paciani, Gesa Dünnweber, Johannes Poersch et al. (+3 more)
The microscopic origin of the pseudogap phase constitutes a longstanding puzzle related to the emergence of high-temperature superconductivity in cuprate materials. In this work, we develop an effective model for doped antiferromagnets in terms of fluctuating stripes, or string-like domain walls, which obscure the antiferromagnetic order of the
spin background. The open ends of such domain walls of the N'eel order are treated as
vortices in the resulting
lattice gauge theory. We numerically evaluate the phase diagram by classical Monte Carlo simulations, using percolation-based
geometric order parameters to diagnose hidden N'eel order. At high temperatures, we identify a BKT-type crossover in which the domain wall ends become deconfined. We interpret this as the $T^*$ crossover from the hidden order regime to the paramagnetic metal above. At low temperatures, we identify stripe instabilities. Predictions of our effective model can be tested in ultracold
fermion quantum simulators.
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All authors Gaia De Paciani, Gesa Dünnweber, Johannes Poersch, Simon M. Linsel, Henning Schlömer, Fabian Grusdt
Mesoscale and Nanoscale Physics
Topological classification through knotted graphs: Fermi surface dispersions and Lifshitz transitions
Hakan Akgün, Xianquan Yan and Ching Hua Lee
Knot theory has provided a rich topological taxonomy for band structures, but its reach is fundamentally limited:
knot invariants classify only 1D nodal lines at gap closure, and cannot encode the full dispersion or rich Fermi surface structure of realistic materials. Here we show that knotted graphs (
knots that admit graph-like intersections in 3D space) - which have so far been elusive in condensed matter literature - provide a unified topological
language for classifying the entire band dispersion, and even the eigenstate
topology in some contexts. We propose a new framework beyond the existing Yamada
polynomials that can topologically characterize the intricacies of realistic Fermi surfaces completely, crucially including how their multiple disconnected pieces are nested. This yields the Yamada set, a boundary-resolved extension which organizes the full topological
evolution across energy into a Yamada sequence: a compact dispersion-level fingerprint directly tied to experimental signatures of Lifshitz transitions. Our framework is demonstrated with DFT-based band structures of real materials. Beyond dispersion-level classifications, this framework can be extended to non-Hermitian exceptional surfaces, where Berry-
curvature flux further equips the knotted-graph skeleton with a directed Abelian edge flow that also captures the eigenstate
topology.
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Statistical Mechanics
Feng He, Arthur Hutsalyuk, Giuseppe Mussardo et al. (+1 more)
How rapidly does order give way to randomness, and can
quantum coherence accelerate this process? We address these questions through the paradigmatic problem of card shuffling, formulated as a random walk on the symmetric group $S_n$. We first recast the random-transposition walk studied by Diaconis and Shahshahani, as well as more general walks generated by conjugacy classes of $S_n$, in continuous time. We then identify the transition
matrix of each classical walk with a permutation
Hamiltonian generating a corresponding
unitary quantum walk. Purely
unitary evolution, however, does not generically converge to the uniform distribution in the classical sense of mixing: coherence preserves information rather than erasing it. We therefore embed the problem into a
quantum stochastic walk, where coherent dynamics competes with the dissipative process responsible for classical mixing. In this setting,
quantum coherence assists randomization. We prove that it can only decrease the distance from the uniform distribution in the computational basis and can therefore accelerate mixing. An analysis of the slowest mode yields a criterion for the coupling strength required to produce an appreciable speedup. Finally, numerical results reveal a scaling collapse of the ratio between
quantum and classical mixing times onto a simple one-parameter form. Our results illustrate how coherence and dissipation can cooperate in the emergence of randomness in walks on permutation groups.
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All authors Feng He, Arthur Hutsalyuk, Giuseppe Mussardo, Andrea Stampiggi
Statistical Mechanics · Cross-listed from quant-ph
Noise-resilient sequential circuits for generating quantum order
Konstantin Gattinger, Julian Boesl, Max McGinley et al. (+2 more)
Sequential
circuits provide an optimal linear-depth route to unitarily preparing long-range ordered
quantum states, but
circuit-level noise can be far more damaging than noise applied after preparation: local errors may be propagated by subsequent gates into nonlocal defects that destroy the target order. In this work, we present classes of
unitary sequential
circuits that prepare certain non-trivial orders in the presence of Pauli noise. Our constructions exploit the spatial structure of the syndromes of the target state, which in certain cases allows us to systematically suppress the propagation of errors using strictly local gates. The strategy can be applied both to
symmetry-breaking order, for which we present a 3D example, and to topological order, which we showcase on a 4D version of the toric code. We also highlight how this stability against errors necessitates non-Clifford gates, and how measurement-feedback loops can be used to stabilize lower-dimensional states as well.
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All authors Konstantin Gattinger, Julian Boesl, Max McGinley, Michael Knap, Frank Pollmann
Superconductivity
Strain-Induced Helical Superconductivity and the Zero-Field Diode Effect
Raigo Nagashima and Jörg Schmalian
Motivated by the strain-induced zero-field superconducting diode effect observed in PbTaSe$_2$, we identify a mechanism by which strain generates nonreciprocal superconducting transport without magnetism or an external
magnetic field. Uniaxial strain mixes a dominant $s$-wave order parameter with a subdominant two-component pairing channel and enhances their
symmetry-allowed Lifshitz coupling. Beyond a critical strain, this coupling drives a transition into a helical state with spontaneously selected finite Cooper-pair momentum and broken time-reversal
symmetry. The resulting diode effect is generically non-monotonic in strain and exhibits distinct responses for currents parallel and perpendicular to the residual mirror plane, consistent with experiment. Our theory predicts that reversing the principal strain switches the diode direction by $90^\circ$, while shear strain rotates it continuously. These results establish strain as a
symmetry-selective means of creating, controlling, and diagnosing spontaneous helical superconductivity.
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Statistical Mechanics
The price of locality: Maxwell-Cattaneo charge transport in Schwinger-Keldysh effective field theory
Andrea Amoretti, Matteo Anselmi and Daniel K. Brattan
We determine the conditions under which the nonlinear Maxwell-Cattaneo theory of charge transport admits a local Gaussian Schwinger-Keldysh
embedding with a particular modified dynamical KMS
symmetry. We show that treating the additional vector as intrinsically dissipative fundamentally modifies the
entropy-current analysis: the hydrostatic generating functional no longer fixes all
entropy-current improvements, which must instead be supplied independently. Subsequently we discuss the additional constraints not contained in the hydrodynamic analysis that are imposed by the modified KMS transformation becoming a
symmetry of the action. We both interpret and supply the corresponding
stochastic quasi-hydrodynamics.
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Strongly Correlated Electrons · Cross-listed from hep-th
Integrable Chiral Quantum Field Theories with Spacetime-Dependent Interactions
Pradip Kattel
We construct a class of integrable chiral fermionic
quantum field theories with interactions that depend on both space and time. The construction starts from a
unitary, regular, difference-form two-body scattering
matrix satisfying braiding unitarity and the Yang–Baxter equation. Each freely moving right- or left-moving particle carries a characteristic coordinate that remains constant along its trajectory, and the scattering
matrix depends on differences of these coordinates. The many-body amplitudes form a discrete connection over the coordinate-ordering sectors. The Yang–Baxter equation gives local path independence, while periodic winding on a spatial circle produces
quantum Knizhnik–Zamolodchikov (qKZ) difference equations expressing global flatness. Once a reference amplitude satisfying the exchange and qKZ constraints is specified, these transport equations determine the exact wavefunction in every fixed-particle-number sector. Independent reparametrizations of the right- and left-moving characteristics give couplings that depend on both space and time. For the chiral $SU(2)$ Gross–Neveu realization, we solve the qKZ equations for this full characteristic family using off-shell Bethe vectors. The resulting amplitudes are written in the characteristic labels, and their pullbacks give exact many-body wavefunctions for the corresponding space-time-dependent couplings. The two-body amplitude is a ratio of Gamma functions that resums the phase shifts from successive scattering processes. Equal-slope affine maps give a spatially homogeneous specialization in which the coupling depends only on time, and the Bethe ansatz with constant coupling is recovered when the qKZ step vanishes.
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