Materials Science · Cross-listed from physics.chem-ph
Gas Mixture Diffusion and Distribution in the Porous ZIF-90 Framework
Ashok Yacham, Tarak K. Patra and Jithin John Varghese
Understanding how gas mixtures diffuse and distribute within porous frameworks is central to designing advanced separation and storage materials. Here, we investigate the transport and spatial distribution of binary gas mixtures in a porous metal organic framework, viz., ZIF-90, using molecular simulations. We perform grand canonical Monte Carlo (GCMC) simulations to examine the competitive adsorption of carbon dioxide and nitrogen from a binary gas mixture in ZIF-90, while molecular dynamics (MD) simulations are conducted to investigate the transport behavior of the adsorbed molecules within the framework. These integrated simulations reveal that the framework
topology and pore chemistry jointly dictate
diffusion pathways and preferential occupancy of gas species, underscoring their intrinsic interdependence. Competitive adsorption leads to distinct spatial partitioning within the pores, which in turn modulates mixture diffusivity inside the porous medium compared to their bulk properties. Our results provide molecular-level insight into how ZIF-90 accommodates and separates gas mixtures, offering design principles for optimizing metal-organic frameworks in energy and environmental applications.
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Superconductivity
Josephson Diode Effect for a Kitaev Ladder System
Cheng-Rong Xie, Hiroki Tsuchiura and Manfred Sigrist
We study the Josephson diode effect realized purely by geometry in a Kitaev-ladder Josephson junction composed of two parallel spinless $p$-wave chains coupled by an interleg hopping $t_\perp$. The junction is governed by two phases: the superconducting phase difference across the weak link, $\theta$, and the leg-to-leg phase difference, $\phi$. For $\phi\notin \{0, \pi\}$ (mod $2\pi$), time-reversal
symmetry is broken, and the absence of leg-exchange
symmetry leads to a breakdown of the antisymmetry of the current-phase relation, yielding nonreciprocal Josephson transport without
magnetic fields or
spin-orbit coupling. By resolving transport into bonding and antibonding channels defined by $t_\perp$, it is shown that the leg phase acts as an effective phase shift for interband ($p_\nu/p_{-\nu}$) tunneling, whereas the same-band ($p_\nu/p_\nu$) contribution remains unshifted. These channels arise at different perturbative orders and, together with the $4\pi$-periodic Majorana channel that emerges near the topological transition, interfere to produce a pronounced diode response. The class-D Pfaffian invariant identifies the parameter regime where the ladder hosts Majorana zero modes. Bogoliubov-de Gennes calculations reveal a dome-like dependence of the diode efficiency $\eta$ on $t_\perp$: $\eta\to 0$ for $t_\perp\to 0$ and for large $t_\perp$, with a maximum at intermediate coupling that is tunable by $\phi$. The present results establish a field-free, geometry-based route to superconducting rectification in one-dimensional topological systems and specify
symmetry and
topology conditions for optimizing the effect in ladder and network devices.
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Mesoscale and Nanoscale Physics
In-Plane Field induced Quantized Longitudinal Conductivity in Magnetic Topological Insulators
Ting-Hsun Yang, Yaochen Li, Peng Zhang et al. (+9 more)
We report the discovery of an in plane quantization (IPQ) state in trilayer
magnetic topological
insulators, characterized by a quantized longitudinal conductivity of e2/h under strong in-plane
magnetic fields. This state emerges at a
quantum critical point separating
quantum anomalous
Hall phases tuned by field angle and orientation, directly linking gap-closing behavior to quantized criticality. Temperature and gate dependent transport measurements, supported by a self consistent approximation model, reveal that electron hole puddles dominate charge transport in this regime, highlighting the essential role of
impurity disorder in stabilizing quantized critical transport. These findings establish a tunable experimental framework that connects gap-closing physics with universal conductivity, offering both microscopic insight into critical transport in
magnetic topological
insulators and a robust platform for probing
quantum criticality in topological systems.
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All authors Ting-Hsun Yang, Yaochen Li, Peng Zhang, Penghao Zhu, Hung-Yu Yang, Eun Sang Choi, Kaiwei Chen, Wenqiang Cui, Kin Wong, Peng Deng, Gang Qiu, Kang L. Wang
Mesoscale and Nanoscale Physics
Direct Visualization of the Magnetic Monopole Field in a 3D Artificial Spin Ice
Arjen van den Berg, Peter Rickhaus, Frank Barrows et al. (+2 more)
Magnetic monopoles, long hypothesised as fundamental particles carrying isolated
magnetic charge, emerge in
spin-ice systems as fractionalised excitations governed by the ice rule. Yet their three-dimensional field structure has never been directly visualised. Here, we use two-
photon lithography and processing to fabricate a fully three-dimensional artificial
spin-ice
lattice with diamond-bond geometry. We then use scanning nitrogen-vacancy magnetometry to directly measure the stray
magnetic fields of both charge-neutral and monopole vertices. We find that ice-rule vertices produce antivortex textures directly above their vertices, stabilised by the local frustrated two-in/two out ordering principle. Direct imaging of the monopole stray field shows a highly divergent profile. By correlating experiment with micromagnetic simulations and performing a multipole expansion of the reconstructed magnetisation, we reveal that monopoles in 3DASI are non-trivial micromagnetic entities, carrying both
magnetic charge and an intrinsic moment, giving rise to anisotropic interactions that are dependent upon the quasiparticles position on the
lattice. Results suggest that as monopoles separate under an applied field, the dipolar contribution to their interaction reorients relative to the underlying Coulombic field, revealing that monopole coupling is tunable through geometry, being set by the local vertex
topology. These findings establish 3DASI as a programmable
magnetic metamaterial in which nanoscale geometry governs the energetics and dynamics of emergent
magnetic charges.
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All authors Arjen van den Berg, Peter Rickhaus, Frank Barrows, Cristiano Nisoli, Sam Ladak
Soft Condensed Matter
Unexpected Behavior of Ultra-Low-Crosslinked Microgels in Crowded Conditions
Susana Marín-Aguilar and Emanuela Zaccarelli
Ultra-low-crosslinked (ULC) microgels are among the softest colloidal particles nowadays routinely synthesized experimentally. Despite a growing literature of experimental results, their microscopic behavior under crowded conditions is yet to be revealed. To this aim, we resort to realistic monomer-resolved computer simulations to investigate their structural, mechanical, and dynamical properties across a wide range of packing fractions. Using particle-resolved analyses, we unveil the role of outer chains in the ULCs, which manifest in peculiar behaviors, utterly different from those of regularly crosslinked microgels. In particular, we report the absence of faceting and the dominance of interpenetration between microgels at high densities. Furthermore, we observe a strong suppression of the structural reentrance characteristic of Hertzian-like particles, that is accompanied by the lack of a dynamical arrest transition, even well above random close packing. We further explore the change of behavior of the suspensions by lowering the crosslinker concentration and the single-particle density, providing strong evidence of the uniqueness of ULCs in the current landscape of microgels. Altogether, our results establish ULCs as a distinct class of soft colloids in which polymeric degrees of freedom are highly predominant over colloidal ones, providing for the first time a robust, microscopic framework to interpret their unusual behavior.
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Strongly Correlated Electrons
Short-range Spin Freezing State in the Double Trillium Lattice Spin-Liquid Candidate KSrFe$_2$(PO$_4$)$_3$ Revealed via $^{31}$P NMR
Sebin J. Sebastian, Q. -P. Ding, A. A. Tsirlin et al. (+2 more)
A comprehensive $^{31}$P
nuclear magnetic resonance (NMR) study, combined with thermodynamic measurements and first-principle band-structure calculations, has been conducted to explore the ground state of the $S = 5/2$ double trillium
lattice antiferromagnet KSrFe$_2$(PO$_4$)$_3$. Our experimental results indicate that the
magnetic ground state is neither a conventional three-dimensional (3D) long-range order (LRO) nor a pure gapless
spin-
liquid state, as conjectured previously [Boya et al., APL Mater. 10, 101103 (2022)]. Specifically, the observation of a nearly field-independent NMR linewidth below $T^{*}$ = (3.5 $\pm$ 0.4) K, and a significant enhancement of
spin-
spin relaxation rate $1/T_2$ below $2T^{*}$ (where $T^{*}$ is the characteristic temperature identified from the
magnetic susceptibility), indicate a complex
magnetic ground state where
spin freezing coexists with persistent dynamics. Furthermore, we argue that the lack of
magnetic LRO and the persistence of strong
magnetic fluctuations in KSrFe$_2$(PO$_4$)$_3$ are unlikely to originate from intersite K/Sr disorder, rather arise due to intrinsic
magnetic frustration. Our findings position KSrFe$_2$(PO$_4$)$_3$ into a broader family of geometrically frustrated magnets characterized by coexisting
spin freezing and pronounced
antiferromagnetic fluctuations, marking it as a promising platform for investigating exotic phenomena in 3D frustrated magnets.
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All authors Sebin J. Sebastian, Q. -P. Ding, A. A. Tsirlin, R. Nath, Y. Furukawa
Materials Science
Photo-induced switching of magnetisation in the epsilon-near-zero regime
Héloïse Damas, Carl S. Davies, Petr M. Vetoshko et al. (+3 more)
The possibility of controlling
spins using ultrashort light and strain pulses has triggered intense discussions about the mechanisms responsible for
magnetic re-ordering. All-optical magnetisation switching can be achieved through ultrafast heat-driven demagnetisation or transient modifications of
magnetic anisotropy. During the phononic switching of
magnetic dielectrics, however, mid-infrared optical excitations can modify the
crystal environment via both the thermal quenching of anisotropy and the generation of strain respectively, with the relative distinction between these thermal and non-thermal processes remaining an open question. Here, we examine the effect of mid-infrared pulses tuned to the frequency of optical
phonon resonances on the labyrinthine domain structure of a cobalt-doped yttrium iron garnet film. We find that the labyrinthine domains are transformed into stable parallel stripes, and quantitative micromagnetic calculations demonstrate this stems predominantly from a partial quenching of the anisotropy. Contrary to conventional wisdom, however, we find that this heat-facilitated process of magnetisation switching is spectrally strongest not at the maximum of absorbed optical energy but rather at the epsilon-near-zero points. Our results reveal that the epsilon-near-zero condition provides an alternative pathway for
laser-driven control of magnetisation, even when the underlying mechanism is primarily thermal.
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All authors Héloïse Damas, Carl S. Davies, Petr M. Vetoshko, Vladimir I. Belotelov, Andrzej Stupakiewicz, Andrei Kirilyuk
Materials Science · Cross-listed from physics.ins-det
Impact of the lead factor of neutron irradiation on the magnetic properties of RPV steels
Sebastián Passanante, Dafne Goijman, M. R. Neyra Astudillo et al. (+5 more)
Materials used in
nuclear reactors are constantly exposed to the effects of
neutron irradiation, which leads to changes in their mechanical properties. In particular, the steels employed in reactor pressure vessels experience a reduction in the ductile-to brittle transition temperature. Given that the pressure vessel is a non-redundant component, understanding this phenomenon is of significant interest. In this work, we focus on studying the effects of accelerated irradiation by maintaining constant
neutron fluence while varying
neutron flux, which results in different lead factors. This approach enables the extrapolation of accelerated test results to real operational conditions of the reactor pressure vessels. In our study, we analyzed irradiated steels using three
magnetic techniques. Each technique responds differently to the microstructural changes induced by irradiation, allowing for a better characterization of its effects on the material. Through DC magnetometry, the analysis of minor loops shows that the remanence, coercivity, and saturation of the steel depend not only on the fluence with which the material was irradiated but also on the irradiation rate, which means, more specifically, on the lead factor. The AC susceptibility technique shows that the response of the irradiated steel to the applied
magnetic field increases with fluence but also with the lead factor. For the real part of XAC, there is an increase with the lead factor, while the imaginary component of XAC grows with the size of the nanoprecipitates. Finally, Barkhausen noise measurements show a clear increase in the RMS of the signal with the lead factor.
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All authors Sebastián Passanante, Dafne Goijman, M. R. Neyra Astudillo, Carlos D. Anello, Rodolfo Kempf, Julián Milano, Martín Gómez, Joaquín Sacanell
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Joint control of coherent transmission, reflection, and absorption
Shiyu Li, Dongha Kim, Shanhui Fan et al. (+1 more)
Controlling multiple wave properties simultaneously poses a key challenge in coherent control of wave transport. We present a theory for joint coherent control of transmission, reflection, and absorption in linear systems. We prove that the numerical range provides the mathematical structure governing achievable responses, and reveal non-abelian effects due to non-commutativity between transmission, reflection, and absorption
matrices. We provide an
algorithm to achieve arbitrary target responses. Our results establish a theoretical foundation for joint coherent control of waves.
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All authors Shiyu Li, Dongha Kim, Shanhui Fan, Cheng Guo
Disordered Systems and Neural Networks · Cross-listed from quant-ph
From single-particle to many-body chaos in Yukawa–SYK: theory and a cavity-QED proposal
David Pascual Solis, Alex Windey, Soumik Bandyopadhyay et al. (+2 more)
Understanding how
quantum systems transition from integrable to fully chaotic behavior remains a central open problem in physics. The Sachdev–Ye–Kitaev (SYK) model provides a paradigmatic framework for studying many-body chaos and holography, yet it captures only the strongly correlated limit, leaving intermediate regimes unexplored. Here, we investigate the Yukawa–SYK (YSYK) model, where bosonic fields mediate random fermionic interactions, and demonstrate that it naturally bridges single-particle and many-body chaos. Using spectral and dynamical chaos markers, we perform a comprehensive finite-size characterization of the YSYK model. We show that the interaction strength acts as a tunable control parameter interpolating between the SYK$_2$ and SYK$_4$ limits, and introduce a framework enabling direct and quantitative comparison with these
benchmark models. In the intermediate regimes, we uncover distinct dynamical regimes marked by partial ergodicity breaking, prethermalization plateaus, and incomplete scrambling. Finally, we propose a feasible optical-cavity implementation of the YSYK model using ultra-cold atoms. Our results establish the YSYK model as a unifying platform connecting single-particle and many-body chaos, paving the way for experimental observation of these phenomena.
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All authors David Pascual Solis, Alex Windey, Soumik Bandyopadhyay, Andrea Legramandi, Philipp Hauke
Other Condensed Matter
Experimental Study of a Vortex Spin-Torque Oscillator in an MTJ with a Vortex Polarizer
Maksim Stebliy, Alex Jenkins, Luana Benetti et al. (+1 more)
Spin-torque nano-oscillators (STNOs) are promising nanoscale microwave sources for spintronic applications, serving as signal generators or elements in neuromorphic computing systems. In this paper, we investigate the experimental realization of an oscillator based on a
magnetic tunnel junction (MTJ) comprising two
magnetic layers: a reference layer (RL) and a free layer (FL). We demonstrate that when
magnetic vortices with opposite chirality and polarity are formed in the layers, the application of a current induces auto-oscillations even in the absence of external
magnetic fields. This effect is observed in devices with diameters ranging from 800 to 1000 nm, exhibiting oscillation frequencies between 110 and 60 MHz. The underlying mechanism is attributed to the action of a
spin current with
vortex-like polarization injected from the RL, interacting with the
magnetic vortex in the FL. This interaction generates a local out-of-plane effective field due to
spin-transfer torque, which acts on the
vortex core and initiates its motion. The observed mechanism differs qualitatively from the case of uniformly polarized
spin currents perpendicular to the plane, where the resulting in-plane field acts on the planar components of the
vortex magnetization.
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All authors Maksim Stebliy, Alex Jenkins, Luana Benetti, Ricardo Ferreira
Disordered Systems and Neural Networks
Interpretable disorder-promoted synchronization and coherence in coupled laser networks
Ana Elisa D. Barioni, Arthur N. Montanari and Adilson E. Motter
Coupled
lasers offer a promising approach to scaling the power output of photonic devices for applications demanding high frequency precision and beam coherence. However, maintaining coherence among
lasers remains a fundamental challenge due to desynchronizing instabilities arising from time delay in the optical coupling. Here, we depart from the conventional notion that disorder is detrimental to synchronization and instead propose an interpretable mechanism through which heterogeneity in the
laser parameters can be harnessed to promote synchronization. Our approach allows stabilization of pre-specified synchronous states that, while abundant, are often unstable in systems of identical
lasers. The results show that stable synchronization enabling coherence can be frequently achieved by introducing intermediate levels of random mismatches in any of several
laser constructive parameters. Our results establish a principled framework for enhancing coherence in large
laser networks, offering a robust strategy for power scaling in photonic systems.
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Mesoscale and Nanoscale Physics
Electrostatics-induced breakdown of the integer quantum Hall effect in cavity QED
Gian Marcello Andolina, Zeno Bacciconi, Alberto Nardin et al. (+3 more)
We address the prevailing theoretical explanation of the recently observed breakdown of the integer
quantum Hall effect in a two-dimensional electron gas embedded in a metallic split-ring resonator. Within the same single-particle description of quantized
Hall conductance, we compare previously proposed
vacuum-induced transport modifications against an alternative mechanism that explains this breakdown in terms of non-
chiral edge channels arising solely from electrostatic boundary effects. This direct comparison shows that for experimentally relevant parameters, the electrostatic contribution exceeds that of any
vacuum-induced conductance modifications by many orders of magnitude and yields characteristic transport signatures and energy scales that align well with experimental observations. This finding sheds new light on this puzzling phenomenon, supporting an electrostatic rather than a
vacuum-related interpretation that can be directly tested in experiments.
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All authors Gian Marcello Andolina, Zeno Bacciconi, Alberto Nardin, Marco Schirò, Peter Rabl, Daniele De Bernardis
Mesoscale and Nanoscale Physics
Twistraintronics in Square Moire Superlattices of Stacked Graphene Layers
Roberto Carrasco, Federico Escudero, Zhen Zhan et al. (+6 more)
We report the first observation of controlled, strain-induced square moire patterns in stacked
graphene. By selectively displacing native wrinkles, we drive a reversible transition from the usual trigonal to square moire order. Scanning tunneling microscopy reveals elliptically shaped AA domains, while spectroscopy shows strong electronic correlation in the form of narrow bands with split Van Hove singularities near the
Fermi level. A continuum model with electrostatic interactions reproduces these features under the specific twist-strain combination that minimizes elastic energy. This work demonstrates that the combination of twist and strain, or twistraintronics, enables the realization of highly correlated electronic states in moire
heterostructures with geometries that were previously inaccessible.
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All authors Roberto Carrasco, Federico Escudero, Zhen Zhan, Eva Cortes-del Rio, Beatriz Viña-Bausa, Yulia Maximenko, Pierre A. Pantaleon, Francisco Guinea, Ivan Brihuega
Superconductivity
Superexchanges and Charge Transfer in the La$_3$Ni$_2$O$_7$ Thin Films
Yuxun Zhong, Wéi Wú and Dao-Xin Yao
The recent discovery of ambient-pressure superconductivity with $T_c$ above 40 K in La$_3$Ni$_2$O$_7$ thin films represents a significant advance in the field of nickelate
superconductor. Motivated by the experimental reports, here we study an 11-band $d-p$ Hubbard model with tight-binding parameters derived from ab initio calculations, using large scale determinant
quantum Monte Carlo and cellular dynamical mean-field theory. Our results reveal that the major superexchange couplings in La$_3$Ni$_2$O$_7$ thin films can be substantially weaker than in the bulk material at 29.5 Gpa. Specifically, the out-of-plane
antiferromagnetic correlation between Ni$-d_{3z^2-r^2}$ orbitals is reduced by about 27% in film, while the in-plane
magnetic correlations remain largely unaffected. We evaluate the corresponding
antiferromagnetic coupling constants, $J_{\perp}$ and $J_{\parallel}$ using perturbation theory. With regard to charge transfer properties, we find that the biaxial compression in films reduces charge transfer gap. We also resolve the orbital distribution of doped holes and electrons among the in-plane (Ni$-d_{x^2-y^2}$ and O$-p_x/p_y$) and the out-of-plane (Ni$-d_{3z^2-r^2}$ and O$-p_z$) orbitals, uncovering a pronounced particle-hole asymmetry. Theses findings lay a groundwork for the study of low-energy $t-J$ model of La$_3$Ni$_2$O$_7$ films and provide key insights into the understanding of physical distinctions between the film and bulk
bilayer nickelates.
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Materials Science · Cross-listed from physics.flu-dyn
Stresses and fluid flow in lamina cribrosa through anisotropic poroelasticty
Riccardo Cavuoto, Sofia Damian, Luca Deseri et al. (+5 more)
To investigate the mechanical correlations between intraocular pressure (IOP) variations and glaucoma, this study presents a linear transversely isotropic poroelastic model of the lamina cribrosa (LC) based on Reissner-Mindlin plate theory. A key feature of the proposed framework is its analytical tractability, which allows the governing poroelastic equations to be solved in closed form under appropriate mechanical and hydraulic boundary conditions. Within this setting, linearity is used to capture the reversible component of the tissue response, providing a baseline description of the coupled solid-fluid feedback on which more complex time-dependent phenomena, such as viscoelastic effects and remodelling, may build.The results indicate that both strain and stress measures (in the form of shear strain and deviatoric stress measures) peak in the peripheral region of the LC, which is currently suspected to be the initial site of glaucomatous damage. These quantities increase with IOP, suggesting a pressure-dependent mechanical insult to the retinal ganglion
cell (RGC) axons. In parallel, the model predicts a monotonic reduction in fluid content as IOP rises, which may contribute to ischemic phenomena and disc haemorrhages. The influence of material anisotropy was also examined, revealing that isotropic assumptions tend to overestimate the fluid content while underestimating shear strain. Given the current experimental challenges in measuring blood flow within the LC, the proposed model provides a valuable framework for exploring the coupled mechanical-hemodynamic behavior of the tissue and for inverse estimation of its mechanical parameters, such as the stiffness of the opening for the central retinal vessels.
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All authors Riccardo Cavuoto, Sofia Damian, Luca Deseri, Massimiliano Fraldi, Alon Harris, Brent Siesky, Alice Verticchio, Giovanna Guidoboni
Materials Science
Phase controlled multi-terminal Josephson junction in ternary hybrid nanowire
Sabbir A. Kahn, Lukas Stampfer, Sara Marti-Sanchez et al. (+7 more)
This work presents multiterminal Josephson junctions in hybrid
semiconductor-
superconductor InAsSb-Al nanocrosses. Hybrid nanocrosses are grown using molecular beam epitaxy and are formed through As-assisted merging of oppositely directed InAsSb nanowires. We explain this complex ternary merging mechanism using a temperature-dependent phase diagram and investigate the detailed
crystal structure with atomic-resolution imaging. The hybrid nanoscrosses enabled the fabrication of multiterminal Josephson junction devices, which were characterized at low temperatures. The supercurrent through each terminal combination was measured as a function of the density in the junction and the relative phase of the terminals, which was controlled by an external
magnetic field.
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All authors Sabbir A. Kahn, Lukas Stampfer, Sara Marti-Sanchez, Dags Olsteins, Damon James Carrad, Thies Jansen, Jonas Johansson, Jordi Arbiol, Peter Krogstrup, Thomas Sand Jespersen
Statistical Mechanics
XYZ integrability the easy way
Paul Fendley, Sascha Gehrmann, Eric Vernier et al. (+1 more)
Sutherland showed that the XYZ
quantum spin-chain
Hamiltonian commutes with the eight-vertex model transfer
matrix, so that Baxter's subsequent tour de force proves the integrability of both. The proof requires parametrising the Boltzmann weights using
elliptic theta functions and showing they satisfy the Yang-Baxter equation. We here give a simpler derivation of the integrability of the XYZ chain by explicitly constructing an extensive sequence of conserved charges from a
matrix-product operator. We show that they commute with the XYZ
Hamiltonian with periodic boundary conditions or an arbitrary boundary
magnetic field. A straightforward generalisation yields
impurity interactions that preserve the integrability. Placing such an
impurity at the edge gives an integrable generalisation of the Kondo problem with a gapped bulk. We make contact with the traditional approach by relating our
matrix-product operator to products of the eight-vertex model transfer
matrix.
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All authors Paul Fendley, Sascha Gehrmann, Eric Vernier, Frank Verstraete
Statistical Mechanics
Universality Classes with Strong Coupling in Conserved Surface Roughening: Explicit vs Emergent Symmetries
Pedro Gatón-Pérez, Enrique Rodriguez-Fernandez and Rodolfo Cuerno
The occurrence of strong coupling or nonlinear scaling behavior for kinetically rough interfaces whose dynamics are conserved, but not necessarily variational, remains to be fully understood. Here we formulate and study a family of conserved
stochastic evolution equations for one-dimensional interfaces, whose nonlinearity depends on a parameter n, thus generalizing that of the
stochastic Burgers equation, whose behavior is retrieved for n=0. This family of equations includes as particular instances a
stochastic porous medium equation and other continuum models relevant to various hard and soft condensed matter systems. We perform a one-loop dynamical renormalization group analysis of the equations, which contemplates strong coupling scaling exponents that depend on the value of $n$ and may or may not imply vertex renormalization. These analytical expectations are contrasted with explicit numerical simulations of the equations with n=1,2, and 3. For odd n, numerical stability issues have required us to generalize the scheme originally proposed for n=0 by T. Sasamoto and H. Spohn. Precisely for n=1 and 3, and at variance with the n=0 and 2 cases (whose numerical exponents are consistent with non-renormalization of the vertex), numerical strong coupling exponent values are obtained which suggest vertex renormalization, akin to that reported for the celebrated conserved KPZ equation. We also study numerically the statistics of height fluctuations, whose probability distribution function turns out (at variance with cKPZ) to have zero skewness for long times and at saturation, irrespective of the value of n. However, the kurtosis is non-Gaussian, further supporting the conclusion on strong coupling asymptotic behavior. The zero skewness seems related with space
symmetries of the n=0 and 2 equations, and with an emergent
symmetry at the strong coupling fixed point for odd values of n.
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Superconductivity
Pair-mixing induced Time-reversal-breaking superconductivity
Saswata Mandal and Chao-Xing Liu
Experimental evidences of spontaneous time-reversal (TR)
symmetry breaking have been reported for the superconducting ground state in the transition metal dichalcogenide (TMD)
superconductor 4H$_b$-TaS$_2$ or
chiral molecule intercalated TaS$_2$ hybrid superlattices, and is regarded as evidence of emergent
chiral superconductivity. However, the $T_c$ of these TMD
superconductors is of the same order as pristine 1H or 2H-TaS$_2$, which do not show any signature of TR breaking and are believed to be conventional Bardeen-Cooper-Schrieffer
superconductors. To resolve this puzzle, we propose a new type of pair-mixing state that mixes the dominant conventional s-wave pairing channel with the subdominant
chiral p-wave pairing channel via a finite Cooper-pair momentum, based on
symmetry analysis within the Ginzburg-Landau theory. Our analysis shows that the fourth-order terms in the
chiral p-wave channel can lead to a variety of pair-mixing states with spontaneous TR breaking. These TR-breaking superconducting states also reveal a zero-field, junction-free superconducting diode effect that is observed in
chiral molecule intercalated TaS$_2$ superlattices.
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Materials Science
The phase-field model of fracture incorporating Mohr-Coulomb, Mogi-Coulomb, and Hoek-Brown strength surfaces
S Chockalingam, Adrian Buganza Tepole and Aditya Kumar
Classical phase-field theories of brittle fracture capture toughness-controlled crack growth but do not account for the material's strength surface, which governs fracture nucleation in the absence of cracks. The phase-field formulation of Kumar et al. (2020) proposed a blueprint for incorporating the strength surface while preserving toughness-controlled propagation by introducing a nucleation driving force and presented results for the Drucker-Prager surface. Following this blueprint, Chockalingam (2025) recently derived a general driving-force expression that incorporates arbitrary strength surfaces. The present work implements this driving force within a finite-element framework and incorporates representative strength surfaces that span diverse mathematical and physical characteristics-the Mohr-Coulomb, 3D Hoek-Brown, and Mogi-Coulomb surfaces. Through simulations of canonical fracture problems, the formulation is comprehensively validated across fracture regimes, capturing (i) nucleation under uniform stress, (ii) crack growth from large pre-existing flaws, and (iii) fracture governed jointly by strength and toughness. While the strength surfaces examined here already encompass a broad range of brittle materials, the results demonstrate the generality and robustness of the proposed driving-force construction for materials governed by arbitrary strength surfaces.
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