Superconductivity
Electronic structures and superconductivity in Nd-doped La$_3$Ni$_2$O$_7$
Cui-Qun Chen, Wenyuan Qiu, Zhihui Luo et al. (+2 more)
The recent discovery of high-$T_c$ superconductivity in Ruddlesden-Popper (RP) nickelates has motivated extensive efforts to explore higher $T_c$
superconductors. Here, we systematically investigate Nd-doped La$_3$Ni$_2$O$_7$ using density functional theory (DFT) and renormalized mean-field theory (RMFT). DFT calculations reveal that both the
lattice constants and interlayer spacing decrease upon Nd substitution, similar to the effect of physical pressure. However, the in-plane Ni-O-Ni bond angle evolves non-monotonically with doping, increasing to a maximum at 70% ($\sim$ 2/3) Nd doping level and then falling sharply at 80%, which leads to a reduction in orbital overlap. Moreover, Nd doping has a more pronounced effect on the Ni-$d{_{z^2}}$ orbital, demonstrating an orbital-dependent effect of rare-earth substitution. Through the
bilayer two-orbital $t-J$ model, RMFT analysis further shows an $s\pm$-wave pairing
symmetry, with $T_c$ rising to a maximum at about 70% Nd substitution before declining, in agreement with the transport measurements. The variation in $T_c$ can be traced to the competition between continuously enhanced interlayer superexchange coupling $J_\perp^z$ and a gradual decrease in particle density. These results highlight the delicate interplay among structural tuning, orbital hybridization, and superconductivity, providing important clues to design higher-$T_c$ RP nickelate
superconductors.
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All authors Cui-Qun Chen, Wenyuan Qiu, Zhihui Luo, Meng Wang, Dao-Xin Yao
Materials Science
Multimodal Topological Textures Arising from Coupled Structural Orders in SrTiO$_3$
Fernando Gómez-Ortiz, Louis Bastogne and Philippe Ghosez
Magnetic spin topological textures recently found their electrical counterparts in polar
topologies emerging from the condensation of inhomogeneous polar atomic distortions. Here, we further extend the concept to other non-polar atomic degrees of freedom. Taking SrTiO$_3$ as a prototypical example, we investigate from second-principles atomistic simulations, the
equilibrium domain structures and topological textures associated with the natural antiferrodistortive rotations of its oxygen octahedra. % Besides the common 90$^\circ$ antiferrodistortive domain walls (twin boundaries), we identify new metastable 180$^\circ$ domain walls oriented along the $\lbrace100\rbrace_\mathrm{pc}$ direction, when compressive epitaxial strain is applied. These domains exhibit complex antiferrodistortive Bloch- and Néel-like configurations with the later being the most favorable. We also stabilize antiferrodistortive
vortex and antivortex structures which are accompanied by co-localized polarization
vortices and a complex pattern of the local strain field, giving rise to a trimodal topological structures. Our results extends the concept of topological ordering to non-polar structural degrees of freedom and highlights the role of
lattice-mediated couplings in stabilizing complex textures in perovskite
oxides.
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Superconductivity
Odd-frequency Pairing in Josephson Junctions Coupled by Magnetic Textures
Ignacio Sardinero, Jorge Cayao, Rubén Seoane Souto et al. (+1 more)
Josephson junctions coupled through
magnetic textures provide a controllable platform for odd-frequency superconductivity and Majorana physics. Within a tight-binding Green function framework, induced pair correlations and spectral properties are analyzed under various
magnetic and
geometric conditions. When the junction is in the topologically trivial regime, even-frequency singlet pairing is dominant, whereas the topological phase is characterized by the coexistence of Majorana bound states and robust odd-frequency equal-
spin triplet pairing at the interface edges. The odd-frequency polarized triplets reveal a divergent $1/\omega$ behavior when the Majorana states are decoupled, which is intrinsically connected to their self-conjugation property. The zero-frequency divergence evolves into shifted resonances and linear low-frequency behavior once hybridization occurs. A nonmagnetic interruption in the texture separates the topological
superconductor into two topological segments and generates additional inner Majorana modes. When the nonmagnetic barrier is comparable to the inner Majorana states localization length, they hybridize and modify their associated odd-frequency triplet pairing, while the outer edge modes preserve their self-conjugated nature. Tuning the superconducting phase difference further controls the onset of the topological regime and the stability of localized Majorana states. The results highlight the central role of odd-frequency triplet correlations as a probe of topological superconductivity in magnetically engineered Josephson junctions.
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All authors Ignacio Sardinero, Jorge Cayao, Rubén Seoane Souto, Pablo Burset
Statistical Mechanics · Cross-listed from quant-ph
Generalised fractional Rabi problem
Alexander Lopez, Sébastien Fumeron, Malte Henkel et al. (+2 more)
Fractional
quantum dynamics provides a natural framework to capture nonlocal temporal behavior and
memory effects in
quantum systems. In this work, we analyze the physical consequences of fractional-order
quantum evolution using a Green's function formulation based on the Caputo fractional derivative. Explicit iterative expressions for the evolved state are derived and applied to an extended two-level Rabi model, a paradigmatic setting for coherent
quantum control. We find that even in the absence of external driving, the static
Hamiltonian term induces non-trivial
spin dynamics with damping features directly linked to the fractional temporal nonlocality. When a periodically varying driving field is introduced, the competition between energy injection and
memory effects gives rise to a richer dynamical behavior, manifest in the
evolution of
spin polarization, autocorrelation function, and fidelity. Unlike the standard Rabi oscillations characterized by a fixed frequency, the fractional regime introduces controllable damping and dephasing governed by the degree of fractionality. These distinctive signatures could be observable through the Loschmidt echo and autocorrelation function, and would offer potential routes to probe fractional
quantum dynamics experimentally. Our findings open pathways toward exploring
memory-induced dynamical phenomena in other systems effectively described by a two-level approximation, such as
graphene-like materials and topological SSH chains, where non-integer order
evolution may reveal novel topological or relaxation effects.
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All authors Alexander Lopez, Sébastien Fumeron, Malte Henkel, Trifce Sandev, Esther D. Gutiérrez
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Characterizing Liouvillian Exceptional Points Through Newton Polygons and Tropical Geometry
Sayooj P and Awadhesh Narayan
The dynamics of open
quantum systems described by the Lindblad master equation follows according to non-Hermitian operators. As a result, such systems can host non-Hermitian degeneracies called Liouvillian exceptional points (EPs). In this work, we show that Newton polygons and tropical
geometric approach allow identification and characterization of Liouvillian EPs. We use two models – dissipative
spin$-1/2$ system and dissipative superconducting
qubit system – to illustrate our method. We demonstrate that our approach captures the anisotropy and order of the Liouvillian EPs, while also revealing the subtle dependence on the form of the perturbation. Our analytical analysis is supplemented by direct numerical calculations of the scaling and exchange of
eigenvalues around Liouvillian EPs. Our analytical approach could be useful in understanding and designing Liouvillian EPs of desired order.
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Materials Science
Rare-Earth Engineering of NaAlO3 Perovskites Unlocks Unified Optoelectronic, Thermoelectric, and Spintronic Functionalities
Muhammad Imran, Sikander Azam, Qaiser Rafiq et al. (+1 more)
Perovskite
oxides are promising for energy and
quantum technologies, but wide-gap hosts such as NaAlO3 suffer from deep-UV absorption and limited carrier transport. Using first-principles GGA+U+SOC calculations, we investigate Eu3+-, Gd3+-, and Tb3+-doped NaAlO3 and evaluate their electronic, optical, elastic, and thermoelectric properties. Rare-earth substitution is thermodynamically favorable (formation energies 1.2-1.6 eV) and induces strong f-p hybridization, reducing the pristine band gap (about 6.2 eV) to about 3.1 eV for Tb.
Spin-resolved band structures reveal Gd-driven half-
metallicity, Eu-induced
spin-selective
metallicity, and Tb-stabilized p-type semiconducting behavior. The optical spectra show a red-shifted absorption edge (about 2.0-2.2 eV), a large static dielectric response (epsilon1(0) about 95 for Eu), and plasmonic resonances near 4 eV, enabling visible-light harvesting. Elastic analysis indicates mild
lattice softening with preserved ductility (Pugh ratio B/G about 1.56-1.57). Thermoelectric performance is enhanced, with Seebeck coefficients greater than 210 uV/K for Eu and Tb and ZT about 0.45 at 500 K. These results identify rare-earth-doped NaAlO3 as a multifunctional perovskite platform for photovoltaics, photocatalysis, thermoelectrics, and spintronics.
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All authors Muhammad Imran, Sikander Azam, Qaiser Rafiq, Amin Ur Rahman
Superconductivity
Unveiling Intrinsic Triplet Superconductivity in Noncentrosymmetric NbRe through Inverse Spin-Valve Effects
F. Colangelo, M. Modestino, F. Avitabile et al. (+7 more)
NbRe is a non-centrosymmetric
superconductor that has been proposed as a candidate for intrinsic
spin-triplet pairing. However, a conclusive demonstration of triplet pairing in NbRe is yet to be found. To probe the presence of equal-
spin triplet Cooper pairs, we fabricated Py/NbRe/Py trilayers capped with an
antiferromagnetic layer.
Magnetic and electrical measurements reveal an inverse
spin-valve effect, which could indicate equal-
spin triplet superconductivity. The minimal sample structure and the lack of ad hoc engineered interfaces clearly associate our observation to intrinsic triplet correlations of NbRe. The availability of NbRe in thin-film form and the simplicity of the
heterostructure highlight its potential as a scalable platform for superconducting spintronics.
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All authors F. Colangelo, M. Modestino, F. Avitabile, A. Galluzzi, Z. Makhdoumi Kakhaki, A. Kumar, J. Linder, M. Polichetti, C. Attanasio, C. Cirillo
Quantum Gases
Faraday patterns, spin textures, spin-spin correlations and competing instabilities in a driven spin-1 antiferromagnetic Bose-Einstein condensate
Vaishakh Kargudri, Sandra M. Jose and Rejish Nath
We study the formation of transient Faraday patterns and
spin textures in driven quasi-one-dimensional and quasi-two-dimensional
spin-1 Bose-Einstein condensates under the periodic modulation of $s$-wave scattering lengths $a_0$ and $a_2$, starting from the anti-
ferromagnetic phase. This phase is characterized by a Bogoliubov spectrum consisting of three modes: one mode is gapped, while the other two are gapless. When $a_0$ is modulated and half of the modulation frequency lies below the gapped mode, density and
spin Faraday patterns emerge. In that case, in quasi-one-dimension, the
spin texture is characterized by periodic domains of opposite $z$-polarizations. When driven above the gap, the
spin texture is characterized by random orientations of
spin vectors along the condensate axis. Qualitatively new features appear in the driven quasi-two-dimensional condensate. For instance, when driven above the gap, the
spin textures are characterized by anomalous
vortices and antivortices that do not exhibit phase winding in individual
magnetic components. Below the gap, the
spin texture exhibits irregular
ferromagnetic patches with opposite polarizations. The spatial
spin-
spin correlations in quasi-one-dimension exhibit a Gaussian envelope, whereas they possess a Bessel function dependence in quasi-two-dimension. Under the $a_2$-modulation, the density patterns dominate irrespective of the driving frequency, unless the
spin-dependent interaction strength is sufficiently smaller than that of the
spin-independent interaction. The intriguing scenario of competing instability can emerge when both scattering lengths are simultaneously modulated. Finally, we show that the competing instabilities result in a complex relationship between the population transfer and the strength of the quadratic Zeeman field, while keeping all other parameters constant.
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Materials Science · Cross-listed from physics.optics
Valley polarization of graphene via the saddle point
Deepika Gill, Sangeeta Sharma, Peter Elliott et al. (+2 more)
Graphene, and other members of the monolayer Xene family, represent an ideal materials platform for "valleytronics", the control of valley localized charge excitations. The absence of a gap in these semi-metals, however, precludes valley excitation by circularly polarized light pulses, sharply circumscribing the possibility of a lightwave valleytronics in these materials. Here we show that combining a deep ultraviolet linearly polarized light pulse with a THz envelope can induce highly valley polarized states in
graphene. This dual frequency lightform operates by (i) the deep ultraviolet pulse activating a selection rule at the M saddle points and (ii) the THz pulse displacing the M point excitation to one of the low-energy K valleys. Employing both tight-binding and state-of-the-art time dependent density functional theory, we show that such a pulse results in a near perfect valley polarized excitation in
graphene, thus providing a route via the saddle point to a lightwave valleytronics in the gapless Xene family.
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All authors Deepika Gill, Sangeeta Sharma, Peter Elliott, Kay Dewhurst, Sam Shallcross
Mesoscale and Nanoscale Physics
Surface-Localized Magnetic Order in RuO2 Thin Films Revealed by Low-Energy Muon Probes
Akashdeep Akashdeep, Sachin Krishnia, Jae-Hyun Ha et al. (+12 more)
Ruthenium dioxide (RuO2) has recently emerged as a candidate altermagnet, yet its intrinsic
magnetic ground state, particularly in thin films, remains debated. This study aims to clarify the nature and spatial extent of the
magnetic order in RuO2 thin films grown under different conditions. Thin films of RuO2 with thicknesses of 30 nm and 33 nm are fabricated by pulsed
laser deposition and sputtering onto TiO2(110) and Al2O3(1-102) substrates, respectively. Low-energy
muon spin rotation/relaxation (LE-muSR) with depth-resolved sensitivity measurements is performed in transverse
magnetic fields (TF) from 4 K to 290 K. The muSR data collected with a
muon implantation energy of 1 keV reveal that
magnetic signals originate from the near-surface region of the film (<10 nm), and the affected volume fraction is at most about 8.5%. The localized
magnetic response is consistent across different substrates, growth techniques, and parameter sets, suggesting a common origin related to surface defects and dimensionality effects. The combined use of TF-muSR and the study of depth-dependent implantation with low-energy
muons provides direct evidence for surface-confined, inhomogeneous static
magnetic order in RuO2 thin films, helping reconcile discrepancies. These findings underscore the importance of considering reduced-dimensional contributions and motivate further investigation into the role of defects, strain, and stoichiometry on the
magnetic properties of RuO2, especially at the surface.
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All authors Akashdeep Akashdeep, Sachin Krishnia, Jae-Hyun Ha, Siyeon An, Maik Gaerner, Thomas Prokscha, Andreas Suter, Gianluca Janka, Günter Reiss, Timo Kuschel, Dong-Soo Han, Angelo Di Bernardo, Zaher Salman, Gerhard Jakob, Mathias Kläui
Mesoscale and Nanoscale Physics
Far-field radiation of bulk, edge and corner eigenmodes from a finite 2D Su-Schrieffer-Heeger plasmonic lattice
Álvaro Buendía, José Luis Pura, Vincenzo Giannini et al. (+1 more)
Subwavelength arrays of plasmonic nanoparticles allow us to control the behaviour of light at the nanoscale. Here, we develop an eigenmode analysis, employing a coupled electromagnetic dipole formalism, which permits us to isolate the contribution to the far-field radiation of each array mode. Specifically, we calculate the far-field radiation patterns by bulk, edge and corner out-of-plane eigenmodes in a finite 2D Su-Schrieffer-Heeger (SSH) array of plasmonic nanoparticles with out-of-plane dipolar resonances. The breaking of
symmetries in multipartite unit
cells is exploited to tailor the optical properties and far-field radiation of the resonant modes. We prove that the antisymmetric modes are darker and have higher Q-factors than their symmetric counterparts. Also, the out-of-plane nature of the dipolar resonances imposes that all bulk $\Gamma$-modes are dark, while corner and edge states need extra in-plane
symmetries to cancel the far-field radiation; radiation patterns in turn become more complex and concentrated along the array plane with increasing array size.
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All authors Álvaro Buendía, José Luis Pura, Vincenzo Giannini, José Antonio Sánchez Gil
Statistical Mechanics · Cross-listed from quant-ph
Local active error correction from simulated confinement
Ethan Lake
We refine an old idea for performing fault-tolerant error correction in topological codes by simulating confining interactions between excitations. We implement confinement using an array of local classical processors that measure syndromes, broadcast messages to neighboring processors, and move excitations using received messages. The dynamics of the resulting real-time decoder is geometrically local, homogeneous in spacetime, and self-organized, operating without any form of global control. We prove that below a threshold error rate, it achieves a
memory lifetime scaling as a stretched exponential in the linear system size $L$, provided that it has access to $O({\rm polylog}(L))$ noiseless classical bits for each noisy
qubit. When applied to the surface code subject to depolarizing noise and measurement errors of equal strength, numerics indicate a threshold at $p_c \approx 1.5\%$.
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Mesoscale and Nanoscale Physics
Amplification and Detection of Single Itinerant Microwave Photons
Lukas Danner, Max Hofheinz, Nicolas Bourlet et al. (+3 more)
Single-
photon detectors are an essential part of the toolbox of modern
quantum optics for implementing
quantum technologies and enabling tests of fundamental physics. The low energy of microwave
photons, the natural signal path for superconducting
quantum devices, makes their detection much harder than for visible light. Despite impressive progress in recent years and the proposal and realization of a number of different detector architectures, the reliable detection of a single itinerant microwave
photon remains an open topic. Here, we investigate and simulate a detailed protocol for single-
photon multiplication and subsequent amplification and detection. At its heart lies a Josephson-photonics device which uses inelastic Cooper-pair tunneling driven by a dc bias in combination with the energy of an incoming
photon to create multiple
photons, thus compensating for the low-energy problem. Our analysis provides clear design guidelines for utilizing such devices, which have previously been operated in an amplifier mode with a continuous wave input, for counting
photons. Combining a formalism recently developed by Mølmer to describe the full
quantum state of in- and outgoing
photon pulses with
stochastic Schrödinger equations, we can describe the full multiplication and detection protocol and calculate performance parameters, such as detection probabilities and dark count rates. With optimized parameters, a high population of a single output mode can be achieved that can then be easily distinguished from
vacuum noise in heterodyne measurements of quadratures with a conventional linear amplifier. Realistic devices with two multiplication stages with multiplication of $16$ reach for an impinging Gaussian pulse of length $T$ a detection probability of $84.5\%$ with a dark count rate of $10^{-3}/T$, and promise to outperform competing schemes.
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All authors Lukas Danner, Max Hofheinz, Nicolas Bourlet, Ciprian Padurariu, Joachim Ankerhold, Björn Kubala
Soft Condensed Matter
Finite element models for Self-Deployable Miura-folded origami
Suraj Singh Gehlot, Siddhanth Gautam and Sanhita Das
Origami-inspired self-deployable structures offer lightweight, compact, and autonomous deployment capabilities, making them highly attractive for aerospace and defence applications, such as
solar panels,
antennas, and reflector systems. This paper presents finite element frameworks for simulating Miura-origami units in ABAQUS, focusing on two deployment mechanisms: elastic strain energy release and thermally activated shape-
memory polymers (SMPs). Validation against experimental data for elastic deployment demonstrates that the model accurately captures fold trajectories and overall kinematics. Parametric studies reveal the influence of hinge stiffness and damping on deployment efficiency. SMP-based simulations qualitatively reproduce stress-strain-temperature behaviour and realistic shape recovery ratios. The study establishes that predictive numerical models can effectively guide the design of origami-based deployable structures for aerospace and defence applications, while highlighting the challenges associated with hinge modelling, damping effects, and thermomechanical actuation.
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Statistical Mechanics
Exact nonlinear dynamics of single band metallic systems with dissipation: From optical to dc currents
J. M. Alendouro Pinho, B. Amorim, Yuliy V. Bludov et al. (+1 more)
The theory of open
quantum systems is one of the most essential tools for the development of
quantum technologies. A particular area of interest is in the optical response of solid state systems, where dissipation is introduced phenomenologically through the relaxation time approximation and its effects are usually gauged perturbatively. Analytical exact results for driven systems under this approximation are scarce and tipically pertain only to the stationary regime. Here, we obtain the analytical solution for the current response of general single-band tight-binding system driven by a uniform electric field with generic time-dependence under the relaxation time approximation. We explore the effects of dissipation in two limiting cases: A monochromatic field, where we analytically deduce the effect of dissipation on High Harmonic Generation, and a constant electric field, where a generalization for the Esaki-Tsu equation is presented for any single-band tight-binding system. We specify the results for a simple 2D nearest neighbours tight-binding
lattice to emphasize the effect of the scale competition introduced by the two different neighbours in both the monochromatic and constant field cases. Finally, we compare our exact result for the constant field to the one obtained from the usual perturbation theory calculation to probe the validity of the latter.
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All authors J. M. Alendouro Pinho, B. Amorim, Yuliy V. Bludov, J. M. Viana Parente Lopes
Materials Science
Twist-tuned exchange and hysteresis in a bilayer van der Waals magnet
Priyanka Mondal, Sonu Verma, Wenze Lan et al. (+9 more)
Moiré superlattices in twisted
bilayers enable profound reconstructions of the electronic bandstructure, giving rise to correlated states with remarkable tunability. Extending this paradigm to van der Waals magnets, twisting creates spatially varying interlayer exchange interactions that stabilize emergent
spin textures and the coexistence of
ferromagnetic and
antiferromagnetic domains. Here, we demonstrate the emergence of robust
magnetic hysteresis in
bilayer CrSBr upon twisting by an angle of ~ 3{\deg}. This is observed as the corresponding hysteretic
evolution of the
exciton energy, that directly correlates with the
bilayer magnetic state, in
magnetic field dependent photoluminescence measurements. A two-sublattice model captures this behavior, attributing it to the twist-induced reduction of interlayer exchange that stabilizes both parallel and antiparallel
spin configurations across a broad field range. Comparison with experiment enables quantitative extraction of the effective exchange strength. Remarkably, the system exhibits coherent averaging across the moiré supercell, yielding an effective monodomain response characterized by switching into the
antiferromagnetic state, rather than forming
spin textures or fragmented domains. Spatially resolved measurements further uncover local variations in hysteresis loops, consistent with position-dependent modulation of the average exchange interaction. Our results establish twist engineering as a powerful route to programmable
magnetic memories in two-dimensional magnets, harnessing the robustness of
antiferromagnetic order.
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All authors Priyanka Mondal, Sonu Verma, Wenze Lan, Lukas Krelle, Ryan Tan, Regine von Klitzing, Kenji Watanabe, Takashi Taniguchi, Kseniia Mosina, Zdenek Sofer, Akashdeep Kamra, Bernhard Urbaszek
Mesoscale and Nanoscale Physics
Gate Voltage Tunable Second Harmonic Generation in Mono- and Bi-layer Black Phosphene
Yan Meng, Kainan Chang, Yanyan Qian et al. (+2 more)
Black phosphorene (BP) has emerged as a promising platform for tunable nonlinear photonics due to its layer-dependent bandgap, high carrier mobility, and remarkable in-plane anisotropy. This study investigates the second-harmonic generation (SHG) of monolayer and
bilayer BP under an external static electric field, with describing the electronic states by a tight-binding model and the dynamics by
semiconductor Bloch equations. Our results reveal that BP exhibits large second-order nonlinear optical response along the armchair direction, with significant resonant enhancement when the incident
photon energy approaches half of its bandgap. Under an applied electric field of $10^7$ V/m, the effective second-order nonlinear susceptibility of BP can be as large as $10^3$ pm/V, surpassing that of the conventional nonlinear
crystal AgGaSe$_2$ by more than an order of magnitude. With respect to the static electric field induced by gate voltage, we discuss the relation between the electric-field-induced second harmonic (EFISH) generation and conventional SHG – under lower gate voltage, the EFISH approach agrees well with the SHG solutions, whereas the former is no longer applicable under higher gate voltage. Specifically, as the increasing gate voltage, monolayer BP exhibits the bandgap expansion and the corresponding blue-shift in the SHG resonant peak. In contrast,
bilayer BP undergoes a
semiconductor-to-semimetal transition, forming Dirac cone and generating divergent SHG spectra as
photon energy goes to zero. Additionally, the chemical potential allows for precise control over interband and intraband nonlinear responses. This work provides important theoretical foundations for the development of BP-based tunable nonlinear photonic devices and expands the application potential of anisotropic two-dimensional materials in nonlinear optics.
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All authors Yan Meng, Kainan Chang, Yanyan Qian, Luxia Wang, Jin Luo Cheng
Materials Science
Yingchen Peng, Yanan Ge, Wentao Chen et al. (+5 more)
Layered van der Waals (vdW)
magnetic semiconductors open a new avenue for exploring intertwined excitonic and
magnetic phenomena. Here, we investigate this interplay in the vdW antiferromagnet MnPS3, uncovering an exceptionally long
exciton lifetime (~100 {\mu}s) below the Néel temperature (T_N). We demonstrate that the
exciton lifetime is governed by
phonon-assisted nonradiative recombination and thus exhibits a strong temperature dependence. In contrast, the
exciton radiative recombination shows a distinct temperature dependence that is sensitive to
magnetic order. Below T_N, the temperature dependence of the radiative recombination rate is consistent with a
magnon-assisted emission pathway, while above T_N it reflects the combined effects of short-range
spin correlations and
phonons. These findings not only establish MnPS3 as a compelling candidate for excitonic devices due to its long-lifetime and correlation with
magnetic orders but also provide crucial insights into the interplay between
excitons,
spins, and
lattice in vdW
magnetic semiconductors.
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All authors Yingchen Peng, Yanan Ge, Wentao Chen, Zihan Wang, Kang Wang, Kezhao Du, Xingzhi Wang, Ye Yang
Materials Science · Cross-listed from physics.optics
Hot-carrier generation in bimetallic Janus nanoparticles
Hanwen Jin, Chengcheng Xiao, Matias Herran et al. (+3 more)
Energetic electrons and holes generated from the decay of localized surface plasmons in metallic nanoparticles can be harnessed in nanoscale devices for photocatalysis, photovoltaics or sensing. In this work, we study the generation of such hot carriers in bimetallic Janus nanoparticles composed of Au, Ag and Cu using a recently developed atomistic modelling approach that combines a solution of the macroscopic Maxwell equation with large-scale
quantum-mechanical tight-binding models. We first analyze spherical Janus nanoparticles whose unique hot-carrier spectrum can be associated with the spectra of the two hemispheres and the interface coupling and find that under
solar illumination the Ag-Au system exhibits the highest hot-carrier generation rate. For dumbbell-shaped Janus nanoparticles, we observe a significant increase in hot-carrier generation with increasing neck size. This is caused by a dramatic enhancement of the electric field in the neck region. We also study the dependence of hot-carrier generation on the light polarization and find that the largest generation rates are obtained when the electric field is perpendicular to the interface between the two metals due to the maximal dipole coupling with the electric field. The insights from our study will guide the experimental design of efficient hot-carrier devices based on bimetallic Janus nanoparticles.
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All authors Hanwen Jin, Chengcheng Xiao, Matias Herran, Emiliano Cortes, Shiwu Gao, Johannes Lischner
Mesoscale and Nanoscale Physics
Magnetic-Field Control of Tomonaga-Luttinger Liquids in Ta2Pd3Te5 Edge States
Xingchen Guo Anqi Wang, Xiutong Deng, Yupeng Li et al. (+12 more)
Ta2Pd3Te5 is a quasi-one-dimensional transition-metal telluride whose heavy atoms endow the material with strong
spin-orbit coupling, while the
Fermi level inside the bulk gap makes the low-energy electronic structure highly tunable.Theory and early experiments have already identified a wealth of emergent phases in this platform: an excitonic
insulator driven by electron-hole binding, a second-order topological
insulator protected by crystalline
symmetry, a potential topological-protected
quantum-
spin-
Hall edge, and proximity-induced edge supercurrents when coupled to a conventional s-wave
superconductor. These properties make it a promising platform for hosting Majorana zero modes and
quantum computation, provided that time-reversal
symmetry can be broken by a Zeeman gap. In this work, we demonstrate that the one-dimensional edge channels of exfoliated Ta2Pd3Te5 host a robust and tunable Tomonaga-Luttinger
liquid by electrostatic gating because it shifts the chemical potential across the bulk gap without changing the gap size. More importantly, the application of a
magnetic field introduces a Zeeman gap that systematically increases the TLL power-law exponent alpha. Furthermore, rotating the field reveals a pronounced twofold anisotropy–alpha is maximal for a field parallel to the edge and minimal for a perpendicular orientation–originating from an orientation-dependent edge g-factor that is likely amplified by
quantum-confinement-induced orbital-angular-moment quenching. The existence of gate-tunable edge supercurrents together with the field-controlled Zeeman gap provides a direct route to break time-reversal
symmetry in a particle-hole-symmetric superconducting gap and thus to engineer a topological superconducting phase, paving the way towards Majorana-based
quantum devices.
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All authors Xingchen Guo Anqi Wang, Xiutong Deng, Yupeng Li, Guoan Li, Zhiyuan Zhang, Xiaofan Shi, Xiao Deng, Ziwei Dou, Guangtong Liu, Fanming Qu, Zhijun Wang, Tian Qian, Youguo Shi, Li Lu, Jie Shen
Mesoscale and Nanoscale Physics
Atomically resolved electron reflectivity at a metal/semiconductor interface
Ding-Ming Huang, Jian-Huan Wang, Jie-Yin Zhang et al. (+3 more)
An atomically flat interface is achieved between face-centered cubic Al and diamond
lattice Ge via molecular beam epitaxy (MBE). Based on the measurements of scanning tunneling microscopy (STM), we demonstrate an atomically resolved lateral periodic change of the electron reflectivity at the Al/Ge interface. The variation of electron reflectivity is up to 24% in lateral 2 nm. We speculate that the change of reflectivity results from the local electronic states at the Al/Ge interface. This phenomenon provides an atomically non-destructive method for detecting the buried interfacial states in hetero-structures by STM.
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All authors Ding-Ming Huang, Jian-Huan Wang, Jie-Yin Zhang, Yuan Yao, H. Q. Xu, Jian-Jun Zhang
Soft Condensed Matter
Compounding formula approach to chromatin and active polymer dynamics
Takahiro Sakaue and Enrico Carlon
Active
polymers are ubiquitous in nature, and often kicked by persistent noises that break detailed balance. In order to capture the out-of-
equilibrium dynamics of such active
polymers, we propose a simple yet reliable analytical framework based on a compounding formula. Connecting polymeric dynamics to the isolated monomeric behavior via the notion of tension propagation, the formula allows us to clarify rich scaling scenarios alongside corresponding intuitive physical pictures. We demonstrate distinctive transient and steady-state scalings due to the non-Markovian nature of the active noise. Aside from a paradigmatic example of an active Rouse
polymer, we expect the framework to be applicable to wide variety of spatially extended systems including more general
polymers (crumpled globule, semiflexible
polymers etc), fluctuation of growing interface, and an array of particles in single-file configuration.
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Materials Science
Higher-order epitaxy: A pathway to suppressing structural instability and emergent superconductivity
Yuki Sato, Soma Nagahama, Shunsuke Kitou et al. (+11 more)
Molecular beam epitaxy enables the growth of thin film materials with novel properties and functionalities. Typically, the
lattice constants of films and substrates are designed to match to minimise disorders and strains. However, significant
lattice mismatches can result in higher-order epitaxy, where commensurate growth occurs with a period defined by integer multiples of the
lattice constants. Despite its potential, higher-order epitaxy is rarely used to enhance material properties or induce emergent phenomena. Here, we report single-crystalline FeTe films grown via 6:5 commensurate higher-order epitaxy on CdTe(001) substrates. Scanning transmission electron microscopy reveals self-organised periodic interstitials near the interface, arising from higher-order
lattice matching. Synchrotron x-ray diffraction shows that the tetragonal-to-monoclinic structural transition in bulk FeTe is strongly suppressed. Remarkably, these films exhibit substrate-selective two-dimensional superconductivity, likely due to suppressed monoclinic distortion. These findings demonstrate the potential of higher-order epitaxy as a tool to control materials and inducing emergent phenomena.
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All authors Yuki Sato, Soma Nagahama, Shunsuke Kitou, Hajime Sagayama, Ilya Belopolski, Ryutaro Yoshimi, Minoru Kawamura, Atsushi Tsukazaki, Naoya Kanazawa, Takuya Nomoto, Ryotaro Arita, Taka-hisa Arima, Masashi Kawasaki, Yoshinori Tokura
Statistical Mechanics
Phase Transitions Without Instability: A Universal Mechanism from Non-Normal Dynamics
Virgile Troude and Didier Sornette
We identify a new universality class of phase transitions that arises in non-normal systems, challenging the classical view that transitions require
eigenvalue instabilities. In traditional bifurcation theory, critical phenomena emerge when spectral stability is lost; here, we show that transitions can occur even when all
equilibria are spectrally stable. The key mechanism is the transient amplification induced by non-orthogonal eigenvectors: noise-driven dynamics are enhanced not by lowering energy barriers, but by increasing the effective shear of the flow, which renormalizes fluctuations and acts as an emergent temperature. Once the non-normality index $\kappa$ exceeds a critical threshold $\kappa_c$, stable
equilibria lose practical relevance, enabling escapes and abrupt transitions despite preserved spectral stability. This pseudo-criticality generalizes Kramers' escape beyond potential barriers, providing a fundamentally new route to critical phenomena. Its implications are broad: in biology, DNA methylation dynamics reconcile long-term epigenetic
memory with rapid
stochastic switching; in
climate, ecology, finance, and engineered networks, abrupt tipping points can arise from the same mechanism. By demonstrating that phase transitions can emerge from non-normal amplification rather than
eigenvalue instabilities, we introduce a predictive, compact framework for sudden transitions in complex systems, establishing non-normality as a defining principle of a new universality class of phase transitions.
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Materials Science
Higher-Order-Phonon Scattering Governs Targeted Control of Heat Conduction in Bulk Boron Arsenide
Tianhao Li, Yangjun Qin, Dongkai Pan et al. (+3 more)
Conventional approaches for modulating thermal conductivity usually rely on structural modifications and therefore cannot achieve reversible in situ regulation. Targeted
phonon excitation has recently emerged as a promising strategy for dynamically tuning thermal transport, but its applicability has so far been demonstrated mainly in two-dimensional systems. Here, we extend this strategy to a three-dimensional bulk material by taking boron arsenide (BAs) as a representative example. Based on first-principles calculations and
phonon Boltzmann transport analysis, we show that targeted
phonon excitation modulates the thermal conductivity of bulk BAs in a strongly frequency-dependent manner. Within the three-
phonon-only framework, the modulation at 300 K is weak but clearly bidirectional. However, once four-
phonon scattering is included, the modulation changes qualitatively to a predominantly suppressive behavior. In the combined three-
phonon plus four-
phonon (3ph+4ph) framework, the strongest suppression occurs at 20.5 THz, where the relative thermal conductivity decreases to 0.828 and 0.415 for excitation intensities of 5 and 25, respectively. By comparing the 3ph-only and 3ph+4ph results, we show that four-
phonon scattering plays a decisive role in determining the net modulation effect by raising the intrinsic scattering background and promoting a more systematic excitation-induced increase in the scattering of low-frequency heat-carrying
phonons.
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All authors Tianhao Li, Yangjun Qin, Dongkai Pan, Shixian Liu, Han Meng, Nuo Yang
Disordered Systems and Neural Networks
Ergodicity Breaking and High-Dimensional Chaos in Random Recurrent Networks
Carles Martorell, Rubén Calvo, Adrián Roig et al. (+2 more)
The neural model introduced by Sompolinsky, Crisanti, and Sommers (SCS) nearly four decades ago has become a paradigmatic framework for studying complex dynamics in random recurrent networks. In its original formulation, with balanced positive and negative couplings, the model exhibits two phases: a quiescent regime, where all activity ceases, and a regime of ongoing irregular collective activity, termed asynchronous chaos (AC), in which state variables fluctuate strongly in time and across units but average to zero across the network. Building on recent work, we analyze an extension of the SCS model that breaks this coupling balance, yielding a richer phase diagram. In addition to the classical quiescent and AC phases, two additional regimes emerge, marked by spontaneous
symmetry breaking. In the persistent-activity (PA) phase, each unit settles into a distinct, stable activation state. In the synchronous-chaotic (SC) phase, dynamics remain irregular and chaotic but fluctuate around a nonzero mean, generating sustained long-time autocorrelations. Using analytical techniques based on dynamical mean-field theory, complemented by extensive numerical simulations, we show how structural disorder gives rise to
symmetry and ergodicity breaking. Remarkably, the resulting phase diagram closely parallels that of the Sherrington-Kirkpatrick
spin-glass model, with the onset of the SC phase coinciding with the transition associated with replica-
symmetry breaking. All key features of
spin glasses, including ergodicity breaking, have clear counterparts in this recurrent network context, albeit with crucial idiosyncratic differences, highlighting a unified perspective on complexity in disordered systems.
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All authors Carles Martorell, Rubén Calvo, Adrián Roig, Alessia Annibale, Miguel A. Muñoz
Mesoscale and Nanoscale Physics
Topological Magnon-Plasmon Hybrids
Tomoki Hirosawa, Pieter M. Gunnink and Alexander Mook
We study
magnon-plasmon coupling in effectively two-dimensional stacks of van der Waals layers in the context of the band structure
topology. Invoking the quasiparticle approximation, we show that the
magnetic dipole coupling between the plasmons in a metallic layer and the
magnons in a neighboring
magnetic layer gives rise to a Berry
curvature. As a result, the hybrid quasiparticles acquire an anomalous velocity, leading to intrinsic anomalous thermal
Hall and
spin-Nernst effects in ferromagnets and antiferromagnets. We propose
magnetic layers supporting skyrmion
crystals as a platform to realize
chiral magnon-plasmon edge states, inviting the notion of topological
magnon-plasmonics.
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Mesoscale and Nanoscale Physics
Decoherence of Majorana zero modes mediated by gapless fermions
Sauri Bhattacharyya, Marco Grilli and Bernard van Heck
We study the decoherence of a collection of Majorana zero modes weakly coupled to a gapless reservoir of non-interacting
fermions. Using the Born-Markov approximation, we derive a Lindblad master equation for the dissipative dynamics of the Majorana zero modes. Due to the long-range coupling between Majorana zero modes mediated by the gapless reservoir, the Lindblad jump operators are non-local linear combinations of the Majorana operators. We show that, as a consequence, the dissipative dynamics can exhibit long relaxation times, i.e. a slow decay of
fermion parities. A spectral analysis of the Liouvillian shows that the slow-down is suppressed as a power law of the distance between Majorana zero modes. Finally, we validate the Lindblad equation by comparison with unbiased numerical simulations of the time
evolution of the full density
matrix. In particular, these illustrate that non-Markovian dynamics establishes non-local correlations at small times.
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Soft Condensed Matter
Simultaneous optimization of assembly time and yield in programmable self-assembly
Maximilian C. Hübl and Carl P. Goodrich
Rational design strategies for self-assembly require a detailed understanding of both the
equilibrium state and the assembly kinetics. While the former is starting to be well understood, the latter remains a major theoretical challenge, especially in programmable systems and the so-called semiaddressable regime, where binding is often nondeterministic and the formation of off-target structures negatively influences the assembly. Here, we show that it is possible to simultaneously sculpt the assembly outcome and the assembly kinetics through the underexplored design space of binding energies and particle concentrations. By formulating the assembly process as a complex reaction network, we calculate and optimize the tradeoff between assembly speed and quality, and show that parameter optimization can speed up assembly by many orders of magnitude without lowering the yield of the target structure. Although the exact speedup varies from design to design, we find the largest speedups for nondeterministic systems where unoptimized assembly is the slowest, sometimes even making them assemble faster than optimized fully-addressable designs. Therefore, these results not only solve a key challenge in semiaddressable self-assembly, but further emphasize the utility of semiaddressability, where designs have the potential to be faster as well as cheaper (fewer particle species) and better (higher yield). More broadly, our results highlight the importance of parameter optimization in programmable self-assembly, and provide practical tools for simultaneous optimization of kinetics and yield in a wide range of systems.
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Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Balanced ternary formalism of second quantization
Yao Yao
We construct a second-quantized representation with a structure of balanced ternary formalism, which involves three substances in organic molecular materials, namely electron, hole and charge-transfer
exciton, into a uniform framework. The
quantum thermodynamic of
excitons is investigated in a closed and compact manner, benefitting from the interplay of the three substances. In order to be friendly with
quantum simulations, the interactions among them are all described with
unitary transformations. Significantly, the nonconserving dynamics of particle numbers, such as the generation of charge current and the
exciton fission in organic
semiconductors, is consistently expressed by this
unitary formalism on the basis of bosonic coherent states. The
spin degree of freedom is further taken into account, and an exotic molecular
ferromagnetic ordering is induced in a specific configuration of
excitons. This balanced ternary formalism establishes a solid bridge to connect thermodynamics and
quantum simulations.
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