Quantum Gases
Path Integral Monte Carlo on a Sphere
Riccardo Fantoni
We solve numerically exactly a simple toy model to
quantum general relativity or more properly to path integral on a curved space. We consider the thermal
equilibrium of a
quantum many body problem on the sphere, the surface of constant positive
curvature. We use path integral Monte Carlo to measure the kinetic energy, the internal energy and the static structure of a
bosons,
fermions and anyons fluid at low temperatures on the sphere. For
bosons we also measure the superfluid fraction and compare its behavior at the critical temperature with the universal jump predicted by Nelson and Kosterlitz in flat space in the thermodynamic limit at the superfluid phase transition. For
fermions and anyons it is necessary to use the restricted path integral recipe in order to overcome the sign problem. Even if this recipe is exact for the non interacting fluid it reduces to just an approximation for an interacting system. And we make the example of the electron gas at low temperature. Snapshots of the many body path configuration during the
evolution of the computer experiment show that the “speed” of the single particle path near the poles slows down as a consequence of the “hairy ball
theorem” of Poincaré. The influence of
curvature on the thermodynamic and structural properties of the many body fluid is also studied.
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Mesoscale and Nanoscale Physics
Victoria Acosta-Pareja, Valeria M. A. Salinas, Omar J. Suarez et al. (+2 more)
We investigate the
equilibrium magnetization in
ferromagnetic nanoscrews (NSw) using micromagnetic simulations. These systems consist of elongated three-dimensional
magnetic membranes with helicoidal geometry, combining
curvature, torsion ($\mathrm{w}$), and eccentricity ($\epsilon$) along their length. We focus on the influence of these
geometric parameters, together with membrane thickness and inner diameter, on remanent states and coercive fields. Our results, obtained over a broad range of eccentricities and torsions, reveal bistable
magnetic behavior, with
vortex-domain-wall propagation during magnetization reversal. We identify four degenerate configurations of a remarkably stable mixed remanent state. The coercive field is found to increase with eccentricity for structures with a major axis (larger inner diameter) approximately 30% larger than the minor axis (smaller inner diameter), while remaining largely insensitive to variations in torsion. These findings are interpreted in terms of geometry-induced modifications of surface magnetostatic charges on the membrane mantle. Overall, our results demonstrate that nanoscrews exhibit robust bistability under systematic
geometric deformation, together with enhanced coercivity, highlighting their potential for applications in three-dimensional nanomagnetism.
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All authors Victoria Acosta-Pareja, Valeria M. A. Salinas, Omar J. Suarez, Attila Kákay, Jorge A. Otálora
Mesoscale and Nanoscale Physics
Super-Klein tunneling in 2D Lorentzian-type barriers in graphene
Alonso Contreras-Astorga, Francisco Correa, Luis Inzunza et al. (+2 more)
We introduce a two-dimensional model of
spin-1/2 Dirac
fermions in
graphene subjected to a highly tunable electric field, which exhibits super-Klein tunneling. The electric field can be continuously interpolated between two limiting configurations: a uniform electrostatic Lorentzian barrier with translational invariance and a chain of well-separated electrostatic scatterers. We demonstrate that super-Klein tunneling arises naturally as a direct consequence of the intrinsic connection of the model to free-particle dynamics, a relation that is established through methods of supersymmetric
quantum mechanics, which provide an elegant and analytically tractable framework. Besides the mentioned super-Klein tunneling, scale invariance of the model and invisibility of the potential for particles of specific energy are revealed, and possible routes toward experimental realization are discussed.
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All authors Alonso Contreras-Astorga, Francisco Correa, Luis Inzunza, Vit Jakubsky, Raul Valencia-Torres
Disordered Systems and Neural Networks
Physical manifestation of replica symmetry breaking in a quantum glass of bosons with off-diagonal disorder
Anna M. Piekarska and Tadeusz K. Kopeć
Glassiness occurs when disorder and frustration cause local degrees of freedom to freeze despite the lack of long-range order. In systems of interacting
bosons, such glassiness may involve a purely
quantum degree of freedom$\unicode{x2014}$local phases of particle wave functions$\unicode{x2014}$partly analogous to
spins in
spin glasses. However, experimental identification of such phases is difficult because it requires prohibitively long measurement times or recourse to the elusive Edwards-Anderson order parameter. Moreover, the off-diagonal character of the phase makes it seemingly even harder to capture via typical observables. To address this issue, we study a system of strongly interacting
bosons with random hoppings that features off-diagonal glassiness exhibiting replica
symmetry breaking (RSB). We find that the glass phase is compressible, which distinguishes it from the Mott
insulator. Thus, we establish a direct correspondence between phase-based glassy order and a measurable density-based thermodynamic observable. We use a framework adopted from
spin glasses, including the replica trick within the one-step RSB scheme, to obtain meaningful results in the glass phase and to characterize the order parameters, RSB structure, slow relaxation, and compressibility. Glassiness in particle systems could thus be experimentally identified via measurements of compressibility, such as probing density fluctuations or the particle-number response to a trapping potential.
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Statistical Mechanics
Timescale Coalescence Makes Hidden Persistent Forcing Spectrally Dark
Yuda Bi, Chenyu Zhang and Vince D Calhoun
Under coarse observation, unresolved slow forcing can remain dynamically active yet locally invisible to reduced spectral inference. For a solvable driven AR$(1)$
benchmark, the local Whittle/Kullback–Leibler distance from the true spectrum to the best nearby one-pole surrogate obeys $\Dloc(\lambda)=C\lambda^4+O(\lambda^6)$, even though the observed spectrum itself is perturbed at $O(\lambda^2)$. The quartic onset is a
geometric consequence of the reduced model
manifold: the $O(\lambda^2)$ perturbation is partially absorbed by tangent-space reparametrization, and only the normal residual survives. We obtain $C$ in closed form for an AR$(1)$ hidden driver and show that $C$ vanishes as $(a-b)^2$ at timescale coalescence, identifying a spectrally dark regime. We then show that this dark regime is not geometrically inevitable: for a non-degenerate AR$(2)$ hidden driver (second characteristic root $z_2\neq 0$), $C>0$ for all parameter values, including single-root coalescence, because the richer spectral structure cannot be absorbed by the two-dimensional tangent space. The quartic coefficient interpolates smoothly between the two cases as $C\sim z_2^4$ when the second characteristic root vanishes. Together, the AR$(1)$ and AR$(2)$ results yield a classification within the one-pole projection class: the quartic law and the boundary $\lcpop(N)\propto(\log N/N)^{1/4}$ are universal features of the projection geometry within this class, while the dark regime requires the hidden driver's spectrum to match the null family's pole structure.
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Materials Science · Cross-listed from physics.optics
Understanding inhomogeneous crystallization dynamics of phase-change materials in the vicinity of metallic nanoantennas
Luis Schüler, Lukas Conrads, Yingfan Chen et al. (+5 more)
Optical metasurfaces composed of metallic or dielectric scatterers (meta-atoms) promise a powerful way of tailoring light-matter interactions. Phase-change materials (PCMs) are
prime candidates for non-volatile resonance tuning of metasurfaces based on a refractive index change. Precise resonance control can be achieved by locally applying
laser pulses to crystallize a PCM, modifying the dielectric surrounding of meta-atoms. However, the complex crystallization kinetics of PCMs in the vicinity of metallic meta-atoms have not been studied yet. Here, we experimentally investigate metallic dimer
antennas on top of the PCM Ge3Sb2Te6 and address these nanoantennas with
laser pulses. Our study reveals inhomogeneous crystallization caused by the absorption and heat conduction of the metallic nanoantennas. A self-consistent multiphysics model, including electromagnetic, thermal, and phase-transition processes, is employed to simulate the crystallization and understand the resulting resonance shift of the
antennas. This model enables the optimization of the
laser parameters and the geometry of the meta-atoms to achieve an optimal crystallization pattern and resonance shift. Our work paves the way towards complex
antenna geometries optimized for local addressing of PCMs to achieve sophisticated crystallization patterns, enabling on-demand programming of individual nanoantennas within metasurfaces.
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All authors Luis Schüler, Lukas Conrads, Yingfan Chen, Lina Jäckering, Sebastian Meyer, Matthias Wuttig, Thomas Taubner, Dmitry N. Chigrin
Mesoscale and Nanoscale Physics
Dinh Loc Duong
We propose an approach to induce nontrivial bands with non-zero Chern numbers by utilizing strong
spin-orbit coupling in transition metal dichalcogenides with dopants. We demonstrate that a doped state near the valence-band edge induces band inversion with the hybridized host band, leading to topologically non-trivial properties. Calculations for V-doped WSe2 and WS2 confirm this mechanism. The coexistence of
magnetic order and nontrivial
topology in these systems offers a promising platform for exploring the
quantum anomalous
Hall effect.
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Superconductivity
Pressure-Invariant Isotope Effect as Evidence for Electronically Driven Intertwined Order in Pr$_4$Ni$_3$O$_{10}$
Rustem Khasanov, Thomas J. Hicken, Igor Plokhikh et al. (+5 more)
We report
muon-
spin rotation measurements of the pressure dependence of the oxygen-isotope ($^{16}$O/$^{18}$O) effect on the
spin-density wave (SDW) transition in the trilayer Ruddlesden-Popper nickelate Pr$_4$Ni$_3$O$_{10}$. At ambient pressure, the SDW transition shows a finite isotope shift, with $^{16}T_{\rm SDW}=158.04(5)$ K and $^{18}T_{\rm SDW}=159.81(6)$ K. Under hydrostatic pressure, $T_{\rm SDW}$ decreases linearly at nearly identical rates for the two isotope compositions, ${\rm d}\,^{16}T_{\rm SDW}/{\rm d}p=-4.93(5)$ K/GPa and ${\rm d}\,^{18}T_{\rm SDW}/{\rm d}p=-4.90(7)$ K/GPa, such that the isotope shift remains essentially unchanged under compression. The absence of pressure enhancement of the isotope effect points to a predominantly electronic origin of the SDW transition and is consistent with recent inelastic x-ray scattering results, suggesting a new regime of intertwined order in trilayer RP nickelates, which is stabilized by strong
spin interactions.
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All authors Rustem Khasanov, Thomas J. Hicken, Igor Plokhikh, Ekaterina Pomjakushina, Hubertus Luetkens, Zurab Guguchia, Christof W. Schneider, Dariusz J. Gawryluk
Materials Science
From Photons to Electrons: Accelerated Materials Discovery via Random Libraries and Automated Scanning Transmission Electron Microscopy
Boris Slautin, Kamyar Barakati, Utkarsh Pratiush et al. (+10 more)
The real-world implementation of materials prediction
algorithms remains limited by persistent characterization bottlenecks in materials discovery, where
photon-based probe techniques (e.g., XRD or Raman) impose long acquisition times and access latencies, restricting exploration to quasi-ternary composition spaces typically realized as compositional libraries. Here, we argue that a paradigm shift from
photon- to electron-based characterization can realign materials characterization with modern high-throughput synthesis. We formulate cost functions and exploration strategies for STEM-based chemical and structural characterization and use Monte Carlo simulations to show that random chemical libraries, where compositionally distinct regions are co-located within a single specimen and interrogated in situ by electron spectroscopies, can sample high-dimensional composition and phase spaces with orders-of-magnitude greater effective coverage than conventional spread-library/X-ray approaches. We further demonstrate autonomous discovery on a laboratory STEM platform, where ML-based autotuning and scripted control enable iterative region selection and characterization without human intervention. Finally, we outline extensions to labeled or position-encoded libraries that preserve compositional and processing metadata, enabling joint exploration of composition and process spaces. Together, these results establish electron-based, ML-enabled STEM as a scalable pathway toward combinatorially rich materials discovery.
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All authors Boris Slautin, Kamyar Barakati, Utkarsh Pratiush, Christopher D. Lowe, Catherine C. Bodinger, Brandi M. Cossairt, Mahshid Ahmadi, Austin Houston, Timur Bazhirov, Jaehyung Lee, Kamal Choudhary, Gerd Duscher, Sergei Kalinin
Mesoscale and Nanoscale Physics
Quantum Geometry of Moiré Flat Bands Beyond the Valley Paradigm
Xiaoting Zhou, Yi-Chun Hung and Arun Bansil
Flat bands in moiré superlattices provide a fertile ground for correlated and topological phases, governed by their
quantum geometric properties. While the valley-based paradigm captures key features in select materials, it breaks down in a growing class of systems lacking valley structure, where exotic phenomena such as twist-angle-tunable numbers of flat bands emerge. In this work, we develop and analyze tight-binding models for twisted heterobilayers of bipartite
lattices, with a focus on the role of interlayer hybridization in generating flat-band
quantum geometry. We demonstrate that sublattice-selective interlayer tunnelings in twisted dice
lattice and
graphene heterobilayers induce isolated flat bands at zero energy, whose number is tunable by the twist angle. Most importantly, these flat bands exhibit finite Berry
curvature and a
quantum metric of the Chern-
insulator scale, generated through interlayer hybridization. This establishes a mechanism to induce
quantum geometry in moiré flat bands beyond the valley paradigm. Our results chart a route to flat-band
quantum geometry engineering in twisted
bilayer bipartite
lattices, with potential material realizations in
oxide heterostructures, molecular
lattices, and synthetic
quantum matter.
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Mesoscale and Nanoscale Physics
Breakdown of Topological Inheritance and Twist-Induced Quantum Geometry Reconfiguration in Moiré Flat Bands
Yi-Chun Hung, Xiaoting Zhou and Arun Bansil
Since the inception of moiré
quantum matter, a foundational tenet of the field has been that the
quantum geometry of emergent flat bands is faithfully inherited from the low-energy valleys of the constituent monolayers. Here, we demonstrate a breakdown of this longstanding tenet in twisted
bilayers of loop-current-ordered kagome
lattices (tb-LCK). Using microscopic tight-binding modeling, we reveal a twist-induced reconfiguration of
quantum geometry where realistic interlayer hybridization quenches topological inheritance from the monolayer. By tuning the loop-current phase, we identify distinct regimes in which the monolayer Berry
curvature is either substantially redistributed or entirely suppressed in the moiré flat bands. We further show that this
quantum geometric collapse is expected to be readily accessible in vanadium-based kagome metals such as AV$_{\text{3}}$Sb$_{\text{5}}$, and that Floquet engineering via waveguide
laser illumination offers a practical route to turn topological inheritance on and off. Our findings uncover a universal mechanism for
quantum geometric reconstruction, establishing interlayer coupling strength as an independent parameter for tuning band
topology beyond the weakly coupled van der Waals
heterostructure paradigm.
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Soft Condensed Matter
Convective Preheating Enhances Front Propagation in DCPD Frontal Polymerization
M Vijay Kumar, Saujatya Mandal, Siddhant Jain et al. (+2 more)
Frontal polymerization (FP) enables rapid curing of thermosets via a self-sustaining thermal wave, but its propagation mechanism can shift dramatically depending on processing conditions. In this study, we investigate the effect of trigger direction and monomer viscosity - controlled via hold time - on the front velocity in frontal ring-opening metathesis polymerization (FROMP) of dicyclopentadiene (DCPD). Our experiments reveal that at low viscosities, bottom-triggered FP fronts propagate significantly faster, ~50% faster front speed compared to top-triggered ones, driven by buoyancy-enhanced convection that preheats the unreacted monomer ahead of the front, that can have important implications for manufacturing applications. However, with increasing hold time, the monomer viscosity rises steeply, suppressing convection and causing the front velocity for top and bottom triggering to converge. This behavior reflects a convection-to-conduction (thermal-
diffusion) transition in heat transport during FP. Complementary simulations incorporating buoyancy-driven advection reproduce the observed trends and highlight the importance of fluid flow in front dynamics. These results provide new insight into the coupled thermo-fluid-chemical mechanisms in FP offer strategies to tailor front behavior through viscosity and initiation geometry.
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All authors M Vijay Kumar, Saujatya Mandal, Siddhant Jain, Saptarshi Basu, Debashish Das
Materials Science · Cross-listed from physics.geo-ph
A quiet quantum revolution in Earth's deep interior
Renata Wentzcovitch, Laura Cobden, Christine Houser et al. (+2 more)
The Earth's lower mantle hosts a subtle but pervasive
quantum phenomenon: the pressure-induced
spin crossover of iron in its dominant minerals, bridgmanite and ferropericlase. In this transition, iron ions gradually shift from high-
spin to low-
spin electronic states without structural change, altering their volume, compressibility, and elastic properties. Although long recognized experimentally and theoretically, its geophysical significance has only recently become clear through the integration of mineral physics and three-dimensional seismic imaging. The
spin crossover reduces bulk modulus and P-wave velocities while leaving S-wave speeds largely unaffected, producing a distinctive decoupling between P- and S-wave anomalies. This signature is now observed in global
tomography and reconciles seismic observations with realistic mantle temperatures and compositions. Rather than forming a sharp boundary, the crossover extends across most of the lower mantle, acting as a diffuse yet essential control on seismic structure. This work highlights how
quantum-scale electronic transitions influence planetary-scale dynamics and interpretations of Earth's deep interior.
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All authors Renata Wentzcovitch, Laura Cobden, Christine Houser, Grace Shephard, Jingyi Zhuang
Other Condensed Matter · Cross-listed from quant-ph
Christian Boudreault and Nicolas Levasseur
In the presence of a globally conserved charge $N$, a natural question is whether a given separable state can be separated into charge-conserving components. We dub this problem the Symmetric Separability Problem (SSP). On random states, the SSP is answered negatively with probability one for almost all $N$. Using a witness to the failure of symmetric separability, namely the number
entanglement (NE) introduced in arXiv:2110.09388, we show that most symmetric and separable states are actually far from being symmetrically separable, with the NE featuring Gaussian concentration around a strictly positive mean value. We discuss some consequences of our results for
quantum tasks in the presence of a superselection rule or in the absence of a common reference frame. Progress is made on the question of the size of the separable space constrained by $N$. We also touch upon the question of the complexity of SSP, and multiparty
entanglement.
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Statistical Mechanics
Geometric Completion of Thermodynamic Response: From the (T)-(V)-(S)-(P) Compass to Recursive $\lambda$-Jacobian Geometry
Monty Dabas
We develop a rigorous
geometric framework for thermodynamic response in a simple compressible system and connect it to a target-faithful Recognition Kernel construction. Starting from a smooth fundamental relation U(S,V), we derive the Maxwell relations, six constraint-dependent response coordinates, their product identities, and the closure C_P/C_V = K_S/K_T. For any four nondimensional response channels, the pairwise area brackets form an intrinsic skew 4 x 4
matrix of rank at most two satisfying an exact Plucker relation, with a noise-stable falsification bound. We then construct the Recognition bundle E_RK = ker A/(ker A intersect ker Pi) from pulled-back thermodynamic response jets, define the response-generated field Phi_th, and prove that compatible transport descends to a connection whose
curvature is the infinitesimal obstruction to path-independent target reconstruction. A sharp decoder
theorem gives source domination and excludes target-relevant blind modes. A finite Cut-Flow-Jet
theorem, together with an analytic infinite-jet extension, controls recursive response transport and cut grading. Within a declared local, parity-even, diffeomorphism- and gauge-invariant low-derivative class, we classify the minimal action and derive the corresponding metric, gauge, and Recognition-field equations. We also establish exact finite-regulator
quantum identities, a regulator-independent Gaussian continuum theory for positive physical Hessians, reflection positivity,
unitary reconstruction, bosonic anomaly freedom, and stable metric-connection identifiability from propagation, scale, and transport data. The full nonlinear interacting continuum theory and empirical validation remain open.
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Quantum Gases
Emergence of Unique Steady Edge States in Trapped Ultracold Atom Systems
Roland Cristopher F. Caballar
We show that, for a one - dimensional open
quantum system of ultracold atoms trapped in an array of harmonic potentials that is weakly coupled to a background Bose - Einstein Condensate (BEC), a unique steady state emerges at either of the two edges of the array due to the combined effects of excitation via
lasers of these ultracold atoms and decay back to their initial energy levels via emission of excitations into the BEC, acting as an excitation reservoir. We then demonstrate the existence of steady states of the master equation that describes the dynamics of this open
quantum system with respect to the expectation value of the position of the harmonic potential containing these states, and show that these steady states occur at the edges of the array of harmonic potentials trapping these atoms. Using the open
quantum system's master equation to evolve initial states of the system that are trapped in other harmonic potentials in the array numerically over time, we verify the analytic calculations demonstrating the existence of these steady states at the edge of the system, and further demonstrate that these steady states will emerge regardless of the number of atoms trapped in each of the harmonic potentials in the array. We note that the emergence of these edge states irrespective of the initial state of the system is similar to the non-Hermitian skin effect seen in other open
quantum systems, and are of fundamental importance in
quantum technological applications such as
quantum transport and
quantum batteries.
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Superconductivity
Gap Engineered Superconducting Multilayer Nanobridge Josephson Junctions
Giuseppe Colletta, Susan Johny, Hua Feng et al. (+3 more)
We report the realization of multilayer three-dimensional nanobridge Josephson junctions based on Nb/NbN and Nb/TiN superconducting stacks fabricated using electron-beam lithography and chlorine-based dry etching. In this architecture, a high-resistivity nitride layer defines the geometrical weak link, while the top Nb layer sets the overall critical temperature and film quality of the stack. This multilayer design enables engineering of the superconducting gap and proximity effects without relying on focused ion beam milling or
oxide tunnel barriers. The devices are successfully integrated into dc SQUIDs, demonstrating reliable
circuit-level operation. By combining material selectivity with three-dimensional geometry, this platform provides a scalable route toward
oxide-free Josephson junctions suitable for superconducting electronics.
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All authors Giuseppe Colletta, Susan Johny, Hua Feng, Mohammed Alkhalidi, Jonathan A. Collins, Martin Weides
Soft Condensed Matter
Regulation of propulsion in assemblies of thermophoretic nanomotors
Yoann De Figueiredo, Ulysse Delabre, Sébastien Cassagnère et al. (+4 more)
Active particles locally transduce energy into motion, leading to unusual and emergent behaviors. However, current synthetic particles lack sensing and adaptation mechanisms. Here, we demonstrate a novel regulation pathway, through the combined use of thermophoretic propulsion and nanometric building blocks. We build an active fluid composed of artificial nanomotors and study its three-dimensional (3D) dynamics. We use
laser-induced photo-thermal effect to actuate nanoparticles, and probe their self-propulsion within assemblies. Despite significant thermal fluctuations at the nanoscale, our results reveal a strong dependence of the thermophoretic propulsion on the concentration of nanomotors, leading to ultrafast velocities of up to ~ 800 um/s. This unique behavior originates from a strong coupling of the local concentration of nanomotors and the temperature field, which feeds back on the thermophoretic mobility of the nanoparticles. We rationalize our results from independent modeling of all thermal effects, accounting for nonlinearities of thermophoretic self-propulsion. Our results open novel routes for the design and self-regulation of 3D active fluids by thermal processes.
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All authors Yoann De Figueiredo, Ulysse Delabre, Sébastien Cassagnère, Martin Romanus, Jean-Pierre Delville, Marie-Hélène Delville, Antoine Aubret
Materials Science
Temperature-dependent vibrational EELS simulations with nuclear quantum effects
Zuxian He and Ján Rusz
The Time Autocorrelation of Auxiliary Wave (TACAW) method has established a framework for modeling angle-resolved electron energy loss spectroscopy (EELS) of
phonons and
magnons by deriving scattering intensities from the time autocorrelation of the beam wavefunction. This approach enables efficient computation of scattering intensities while naturally accounting for dynamical diffraction and multiple-scattering effects. In the cryogenic regime, vibrational spectra are dominated by
nuclear quantum effects, notably zero-point motion. To capture these effects in low-temperature vibrational EELS, we incorporate thermostatted ring
polymer molecular dynamics (TRPMD) into the TACAW formalism. Our results demonstrate that
nuclear quantum effects lead to significant deviations from classical molecular dynamics predictions in the vibrational spectra of silicon at low temperatures and correctly predict the nearly temperature-independent optical
phonon peak intensities in silicon, consistent with the first Born approximation. The TRPMD-TACAW method provides a robust theoretical tool for probing the low-temperature limit of vibrational EELS, offering a necessary
benchmark for the quantitative analysis of emerging cryogenic scanning transmission electron microscopy experiments.
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Materials Science
Electric-field-induced X-ray Nonreciprocal Dichroism in Hematite
Takeshi Hayashida, Koei Matsumoto, Keito Arakawa et al. (+5 more)
Hematite (alpha-Fe2O3) is a prototypical room temperature antiferromagnet whose time-reversal-odd
magnetic structure has recently attracted renewed
attention. While such
magnetic symmetry can be characterized in terms of higher-order multipoles beyond the
magnetic dipole, their manifestation in measurable physical phenomena has remained largely elusive. In this work, we investigate x-ray absorption near the Fe K-edge of hematite under an applied electric field, which explicitly breaks space-inversion
symmetry. We observe an electric-field-induced x-ray nonreciprocal linear dichroism (E-induced XNLD) that reflects the time-reversal-odd nature of the
magnetic order. Numerical simulations based on ab-initio density functional theory reproduce the observed spectra, including their dependence on the
antiferromagnetic domain and x-ray polarization. Furthermore, a
symmetry-resolved multipole analysis reveals that this response originates from the
magnetic quadrupole and the
magnetic toroidal octupole induced by the applied electric field. These results demonstrate that electric-field-modulated x-ray absorption provides direct access to the antiferroic order of higher-order multipoles in time-reversal-odd antiferromagnets, thereby establishing a general framework to uncover hidden
symmetry properties in
magnetic materials.
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All authors Takeshi Hayashida, Koei Matsumoto, Keito Arakawa, Yves Joly, Sergio Di Matteo, Kenji Tamasaku, Yoshikazu Tanaka, Tsuyoshi Kimura
Soft Condensed Matter
Channel Flow Around an Obstacle in a Two-Dimensional Soft Particles
Bahaa Mazloum, Alexandre Stepanetz, Benjamin Dollet et al. (+1 more)
We numerically study confined channel flow around an obstacle using a two-dimensional soft par- ticle model, inspired by experiments performed in the same geometry. We systematically vary the polydispersity, the external driving force, and the packing fraction of the system. Our simulations capture a broad range of plastic flow phenomenologies, from highly directional, sliding-like motion characteristic of crystalline materials to more isotropic and localized rearrangements typical of amor- phous systems. We identify a threshold value of polydispersity that marks the crossover between crystalline-like and amorphous-like plasticity. In addition, we observe the existence of a critical ex- ternal force, associated with the phenomenon of yield drag, above which the system reaches steady flow and below which it remains arrested. We determine a critical packing fraction above which such yield-drag behavior emerges. Our results provide a comprehensive framework for understanding the interplay between disorder, driving, and the presence of an obstacle in channel flows.
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All authors Bahaa Mazloum, Alexandre Stepanetz, Benjamin Dollet, Misaki Ozawa
Superconductivity
Optically Activated Superconductivity in MgB2 via Electroluminescent GaP Inhomogeneous Phase
Yao Qi, Duo Chen, Qingyu Hai et al. (+2 more)
Experimental results demonstrate a viable strategy for tuning the superconducting properties of MgB2 through the incorporation of an electroluminescent inhomogeneous phase, revealing an interfacial light-
phonon-electron synergistic mechanism that enhances superconductivity in conventional
phonon-mediated systems. By introducing GaP electroluminescent inhomogeneous phases into MgB2 and activating their emission in situ through the application of a bias current during measurements, it is experimentally observed that the localized optical field and electromagnetic near field generated at the interface can effectively couple with the E2g
phonon mode of the Mg-B layers, thereby significantly enhancing the electron-
phonon interaction. As the emission intensity of the inhomogeneous phase increases, the interface light-field-driven mechanism markedly enhances the electron-
phonon coupling constant lambda and leads to a gradual increase in the superconducting transition temperature Tc (with a maximum enhancement of approximately 1.4 K), enabling a tunable enhancement of the superconducting pairing channel in MgB2 without altering its primary chemical composition. In addition, the nanoscale dispersed distribution of the GaP inhomogeneous phase is expected to induce fine-scale defects that act as effective pinning centers and promote densification, resulting in an increase of the critical current density by approximately 69% at 20 K in the self-field and an enhancement of Hirr by about 31.5%. These results indicate that the electroluminescent inhomogeneous phase can synergistically enhance the superconducting performance of MgB2 through two mechanisms: "in situ near-field-enhanced pairing" and "structural pinning-assisted flux optimization", thereby providing a new design strategy for constructing superconducting material systems that can be activated by internal optical fields.
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All authors Yao Qi, Duo Chen, Qingyu Hai, Xiaoyan Li, Xiaopeng Zhao
Strongly Correlated Electrons
Many-body electronic structure, self-doped double-exchange, and Hund metallicity in 1T-CrTe2 bulk and monolayer
Dong Hyun David Lee, Hyeong Jun Lee, Taek Jung Kim et al. (+2 more)
The van der Waals (vdW) ferromagnet 1T-CrTe2 is an emerging spintronics platform, notable for its high Curie temperature (Tc) and intriguing transport properties. However, the fundamental interplay between the electron correlations and magnetism underlying its high Tc still remains elusive. Here, using density functional theory plus dynamical mean-field theory (DFT+DMFT), we identify 1T-CrTe2 as a self-doped double-exchange ferromagnet with pronounced Hund
metallicity. This identification is grounded in the first detailed analysis of its many-body electronic structure, which reveals a dual electronic nature of Cr-d orbitals where itinerant eg electrons coexist with localized t2g moments. The interaction between these orbitals, mediated by Hund's coupling, drives the double-exchange ferromagnetism, establishing 1T-CrTe2 as a Hund metal reminiscent of orbital-selective Mott systems. In the monolayer limit, while this physical picture persists, structural deformation, rather than reduced dimensionality, notably reduces Tc.Our findings offer a new perspective on the high-Tc ferromagnetism in 1T-CrTe2, a mechanism potentially pivotal for other correlated two-dimensional vdW metallic magnets.
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All authors Dong Hyun David Lee, Hyeong Jun Lee, Taek Jung Kim, Min Yong Jeong, Myung Joon Han
Materials Science
Crystal Growth and anisotropic magneto-transport properties of semimetallic LaNiSb3
Haribrahma Singh, Aarti Gautam, Prabuddha Kant Mishra et al. (+2 more)
Single
crystals of LaNiSb$_3$ were grown using the Sn flux method. Structural characterization confirms that LaNiSb$_3$ crystallizes in the orthorhombic $Pbcm$ space group with
lattice parameters $a = 13.0970(2)\,\mathrm{\AA}$, $b = 6.1400(4)\,\mathrm{\AA}$, and $c = 12.1270(4)\,\mathrm{\AA}$. Electrical resistivity measurements demonstrate metallic behavior over the entire temperature range of 3–300~K. The magnetoresistance exhibits a positive anisotropic response, attaining a maximum of $\sim 8\%$ for $H \parallel b$, with a pronounced crossover from quadratic to nearly linear field dependence. Angular-dependent MR measurements reveal a pronounced twofold
symmetry upon
magnetic field rotation within both the $ab$ and $ac$ crystallographic planes up to 50~K, indicating anisotropic charge transport.
Hall resistivity measurements show predominantly electron-type conduction at high temperatures, with an increasing hole contribution upon cooling. The multiband character is further corroborated by the violation of Kohler's scaling and is well described within a semiclassical two-band framework. Collectively, these results suggest that LaNiSb$_3$ exhibits anisotropic multiband electronic transport and is a compelling candidate for exploring structure–property correlations in topological semimetals.
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All authors Haribrahma Singh, Aarti Gautam, Prabuddha Kant Mishra, Rie Y. Umetsu, Ashok Kumar Ganguli
Strongly Correlated Electrons
Role of interstitial $s$ orbital in a model of infinite-layer nickelates
Yan Peng, Rui Peng and Mi Jiang
Motivated by recent angle-resolved photoemission spectroscopy (ARPES) experiments on infinite-layer (IL) nickelates, we employ determinant
quantum Monte Carlo (DQMC) to study the three-orbital Emery model ($d$-$p$ model) coupled to an additional interstitial $s$ orbital retaining the three-dimensional dispersion. Our large-scale simulations reveal that: (1) the interstitial $s$-orbital-derived electron pocket is significantly reduced by the strong interaction but persists upon 20% hole doping, reaching a size comparable to experimental observations; (2) the $d_{x^2-y^2}$-orbital dispersion is strongly renormalized by interactions, leading to a weak $k_z$ dependence consistent with ARPES measurements. Furthermore, compared with the conventional three-orbital $d$-$p$ model, the $d$-$p$-$s$ model exhibits enhanced short-range
antiferromagnetic correlations. These results highlight the crucial role of strong correlations and multi-orbital effects in shaping the low-energy electronic structure and many-body correlations in IL nickelates, and demonstrate the necessity of treating interaction-driven many-body physics within a realistic multi-orbital framework.
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Strongly Correlated Electrons
Tracking the local order parameter through the Hubbard exciton decoherence time in the Mott-Hubbard insulator LaVO3
Alessandra Milloch, Paolo Franceschini, Pablo Villar-Arribi et al. (+9 more)
The prototypical Mott-Hubbard
insulator LaVO3 undergoes a structural phase transition accompanied by the onset of
spin and orbital ordering below 140 K. By combining ultrafast optical pump-probe spectroscopy and two-dimensional electronic spectroscopy, we investigate the interplay between fluctuations of the local
spin and orbital order parameter and the lifetime of high-energy electron-hole excitations. Specifically, we demonstrate that the pump-induced perturbation of the order parameter leads to a change of the Hubbard
exciton decoherence time and, consequently, of its homogeneous linewidth. Dynamical mean-field theory calculations confirm that the
exciton scattering rate is crucially affected by the degree of order of the
spin and orbital
lattices in LaVO3. Our results demonstrate that multi-dimensional ultrafast optical spectroscopy can be used to track the dynamics of the order parameter, thus opening new routes in the study of correlated
quantum materials characterized by intertwined orders.
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All authors Alessandra Milloch, Paolo Franceschini, Pablo Villar-Arribi, Sandeep Kumar Chaluvadi, Pasquale Orgiani, Giancarlo Panaccione, Giorgio Rossi, Yang Liu, Darrell G. Schlom, Kyle M. Shen, Massimo Capone, Claudio Giannetti
Materials Science
Emerging hierarchical dislocation structures: Insights from scanning electron microscopy-electron backscatter diffraction in situ tensile testing and multifractal analysis
Mikhail Lebyodkin, Maxim Gussev, Jamieson Brechtl et al. (+1 more)
Understanding the
evolution of dislocation structures during plastic deformation is critical for predicting the mechanical performance of metallic materials. In this work, we applied in situ scanning electron microscopy/electron backscatter diffraction tensile testing combined with multifractal (MF) analysis to assess deformation-induced dislocation structure
evolution in solution-annealed 304L stainless steel, both in its as-received and
neutron-irradiated states (5.4 displacements per atom). The analysis of kernel average misorientation patterns revealed the formation of hierarchical dislocation arrangements that exhibit clear MF scaling behavior. Despite pronounced visual differences between nonirradiated and irradiated specimens – most notably, the appearance of dislocation channels after irradiation – the singularity spectra suggest that both conditions give rise to similar underlying hierarchical structures. MF analysis provides a quantitative measure of the spatial complexity and self-organization of dislocation patterns, highlighting the accelerated emergence and
evolution of the dislocation structures in irradiated polycrystalline materials, as well as the limitation of their spatial extent. The findings indicate that irradiation not only modifies microstructure but also alters correlation-driven dislocation organization. More generally, they demonstrate that MF analysis is a powerful tool for probing mesoscale deformation mechanisms.
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All authors Mikhail Lebyodkin, Maxim Gussev, Jamieson Brechtl, Tatiana Lebedkina