Soft Condensed Matter
Activity-Driven Dewetting and Rupture in Thin Liquid Films
Preethi M, Daniya Davis and Bhaskar Sen Gupta
Thin-film dewetting is classically governed by an adhesion-mediated spinodal instability in which
curvature-driven
diffusion controls post-rupture coarsening. We show that internal activity fundamentally restructures this instability. Using a minimal microscopic model of an active
liquid film on a solid substrate, we identify a competition between active stresses and film-substrate adhesion that produces two independently regulated dynamical length scales: vertical
liquid accumulation and lateral rupture propagation. While passive films exhibit universal
diffusion-limited growth, $\ell_z(t)\sim t^{1/3}$, activity converts transport from
curvature-controlled
diffusion to persistence-driven motion, yielding a continuous increase of the coarsening exponent from $\approx 0.33$ to $\approx 0.6$. The growth law analysis shows that persistent self-propulsion introduces an advective flux that competes with
curvature-induced chemical potential gradients, enhancing growth when the persistence length becomes comparable to the evolving domain size. Simultaneously, the rupture front transitions from dissipative spreading to strongly accelerated propagation approaching ballistic scaling. This decoupling shows that activity does not simply renormalize effective surface forces but generates a distinct nonequilibrium interfacial instability governed by the balance between persistence length and adhesion. The results provide a minimal physical mechanism linking classical thin-film dewetting to dewetting-like rupture observed in active and biological materials.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Orbitally resolved single-photon emission from an individual atomic vacancy center in a semiconductor
Gagandeep Singh, Xiaodan Lyu, Bi Qi Chong et al. (+11 more)
Atomically confined
spins are emerging as active components in
quantum optoelectronic devices such as
quantum bits and sensors. However, interrogating single
spins at atomic length-scales remains a sizeable challenge, limited by diffraction in conventional optics. Here we show that the highly-local excitation provided by injecting energetic charge carriers from the atomically sharp probe of a scanning tunneling microscope can trigger single-
photon emission from individual atomic vacancy centers in a layered
semiconductor. With an effective spatial resolution of <1 nm, we show that the captured light closely mirrors the orbital
symmetry of the bound-state wavefunction of the vacancy center while
photon correlation measurements confirm single-
photon emission, as reflected in clear
photon anti-bunching signatures. Our results constitute an important step toward the realization of an electrically addressable single-atom
quantum light source and solid-state spinphoton interface, addressed at the atomic-scale.
Read the full abstract ▾
All authors Gagandeep Singh, Xiaodan Lyu, Bi Qi Chong, Ryan Li Yen Tang, Rejaul SK, Yande Que, Ranjith Shivajirao, Thasneem Aliyar, Radha Krishnan, Junxiang Jia, Michael S. Fuhrer, Teck Seng Koh, Weibo Gao, Bent Weber
Mesoscale and Nanoscale Physics
Percolative Instabilities and Sparse-Limit Fractality in 1T-TaS$_2$
Poulomi Maji, Md Aquib Molla, Koushik Dey et al. (+13 more)
The low-temperature metallic phase of 1T-TaS2 may originate from current- and voltage-driven destabilization of the commensurate charge density wave (CDW) in a strongly correlated Mott
insulator, alongside the robust yet rarely realized influence of intrinsic electronic distortions. Electrical pulse-driven transport, combined with second harmonic response, reveals abrupt switching, negative differential resistance (NDR), and multiscale domain-wall reorganization. The free energy analysis identifies a critical order parameter threshold for the Mott-metal transition, with scaling exponents ({\beta} approx 1.3) consistent with 2D percolation. The sparse limit fractal dimension D_{f} approx 0.3 at 10 K, rising to approx 0.9 at 300 K, reflects the hierarchical
evolution of the conductive pathways throughout the temperature. These findings establish a direct connection between fractal percolation, pulse-induced instabilities, and correlated electron transport, offering a framework for controlled access to non-
equilibrium phase transitions in low-dimensional
quantum materials.
Read the full abstract ▾
All authors Poulomi Maji, Md Aquib Molla, Koushik Dey, Bikash Das, Sambit Choudhury, Tanima Kundu, Pabitra Kumar Hazra, Mainak Palit, Sujan Maity, Bipul Karmakar, Kai Rossnagel, Sanjoy Kr Mahatha, Bhaskaran Muralidharan, Shamashis Sengupta, Sanchari Goswami, Subhadeep Datta
Quantum Gases · Cross-listed from physics.atom-ph
Electric-field control of atom-molecule Feshbach resonances
Mara Meyer zum Alten Borgloh, Jule Heier, Fritz von Gierke et al. (+4 more)
Ultracold molecules provide opportunities for exploring
quantum matter, chemical dynamics and information processing thanks to their rich interactions, which can be controlled by external fields.
Magnetic fields tune interactions through Feshbach resonances, enabling the formation of ultracold dimers and triatomic molecules from atom-dimer collisions. Here we demonstrate electric-field control of atom-molecule Feshbach resonances. In mixtures of ground-state sodium-potassium molecules and potassium atoms, electric fields shift resonance positions systematically, revealing specific trimer bound states and their electric-field dependent energies. The response differs markedly from isolated dimers, showing hindered rotation of the molecular constituent near an atom. Electric fields therefore add an independent knob for atom-molecule resonances, open spectroscopic access to triatomic
quantum states, and advance controlled polyatomic
quantum matter.
Read the full abstract ▾
All authors Mara Meyer zum Alten Borgloh, Jule Heier, Fritz von Gierke, Baraa Shammout, Eberhard Tiemann, Leon Karpa, Silke Ospelkaus
Strongly Correlated Electrons
Phonon-Assisted Photoluminescence and Ultrafast Exciton Dynamics in Two-Dimensional Silicon Carbide
Afreen Anamul Haque, Rishabh Saraswat, Aniket Singha et al. (+2 more)
Phonon assisted photoluminescence provides a direct window into
exciton phonon interactions in
semiconductors. Using fully ab initio many-body perturbation theory, including finite momentum Bethe Salpeter calculations, we investigate
phonon-assisted emission and
exciton dynamics in two dimensional (2D) hexagonal silicon carbide (hSiC) and
benchmark its response against 2D h boron nitride (hBN). By explicitly resolving
exciton phonon matrix elements, we identify an electron-
phonon scattering channel mediated by A$^\prime$ high energy longitudinal and transverse optical
phonons as the dominant contributors to sideband formation and quantify their spectral weights. We find that h SiC exhibits pronounced
phonon-assisted sidebands comparable to hBN, despite a smaller
exciton phonon energy separation and fewer resolved replicas. The bright KK
exciton governs near UV zero
phonon emission, while intervalley
excitons acquire radiative character through
symmetry allowed optical
phonon coupling. Temperature dependent scattering rates reveal an ultrashort bright
exciton lifetime of approximately 300 fs at 10 K, highlighting rapid
exciton relaxation driven by intrinsic
phonon channels.
Read the full abstract ▾
All authors Afreen Anamul Haque, Rishabh Saraswat, Aniket Singha, Rekha Verma, Sitangshu Bhattacharya
Superconductivity · Cross-listed from quant-ph
Characterization of Josephson Junction Aging and Annealing Under Different Environments
Rangga P. Budoyo, Rasanayagam S. Kajen, Bing Wen Cheah et al. (+2 more)
Understanding the aging behavior of Josephson junctions and the effect of annealing on junction resistances is important in building large-scale superconducting
quantum processors. Here we study the effects of aging of Al/AlOx/Al Josephson junctions under different storage conditions from immediately after fabrication up to 2 to 3 months. We find that the aging curve follows a logarithmic curve, with the aging amplitude mainly determined by fabrication conditions and the aging rate determined by both fabrication and storage conditions. Junctions stored at ambient laboratory conditions aged faster compared to junctions stored in a nitrogen atmosphere or
vacuum, with the aging speed appreciably changes when the storage condition changed. We also compared the effect of thermal annealing under nitrogen environment with annealing under ambient conditions up to 250$^\circ$C. We find that under nitrogen environment, the resistances decreased at all temperatures tested, while under ambient environment the resistances increased at 200$^\circ$C and decreased at 250$^\circ$C instead. We were unable to decrease the resistance below the initial-time resistance, suggesting a lower limit on the range of resistance tuning.
Read the full abstract ▾
All authors Rangga P. Budoyo, Rasanayagam S. Kajen, Bing Wen Cheah, Long H. Nguyen, Rainer Dumke
Soft Condensed Matter
Thermodynamic effects of solid electrolyte interphase formation from solvation and ionic association in water-in-salt electrolytes
Daniel M. Markiewitz, Michael McEldrew, Conor M. E. Phelan et al. (+6 more)
Water-in-Salt-Electrolytes (WiSEs) are a promising class of next-generation electrolytes. Unlike classical dilute electrolytes or more conventional battery electrolytes, WiSEs are characterised by their super-concentrated salt concentration with only a small amount of water, which gives rise to their expanded electrochemical stability window (ESW). The expansion of the ESW is, in part, due to the formation of an inorganic solid electrolyte interphase (SEI) that passivates the anode; this principle is also important in graphite and Li-metal anodes, and beyond Li-ion technologies. The solvation and ionic associations are key descriptors in understanding the expansion of the ESW. Specifically, as reactions which lead to the SEI (or cathode electrolyte interphase, CEI) must occur at the electrode-electrolyte interface, the distribution of reactants and their various solvation environments are critical. This distribution near the interface is referred to as the electrical double layer (EDL), in the absence of reactions. Here we further develop and analyse a recently proposed thermodynamic theory of hydration and ionic associations in the EDL of WiSEs. We parameterize this theory from bulk molecular dynamics simulations and
benchmark it against EDL simulations, finding good qualitative agreement. Using this thermodynamic theory, we rationalise changes in the ESW through: changes in the activity in the bulk electrolyte through the Nernst equation, which directly changes the stability of the electrolytes; and thermodynamic changes to the kinetics of these reactions, from the Butler-Volmer equation and coupled ion electron transfer kinetics, through the concentration of reactant species in the Helmholtz layer.
Read the full abstract ▾
All authors Daniel M. Markiewitz, Michael McEldrew, Conor M. E. Phelan, Qianlu Zheng, Jasper Singh, Robert S. Weatherup, Rosa M. Espinosa-Marzal, Martin Z. Bazant, Zachary A. H. Goodwin
Materials Science
A Nanocrystal Synthesis Derived Approach to Silver Bismuth Iodide Layered Double Perovskites with Aliphatic Amines: (CnH(2n+1)NH3)4AgBiI8
Pascal Rusch, Ann Mary Antony, Meenakshi Pegu et al. (+9 more)
Lead-free iodide double perovskites are an interesting class of materials since they combine a relatively low toxicity (compared to the lead counterpart) with the small bandgap typical of iodide-based perovskite structures. Their reported number is small due to their lower structural stability compared to the chloride and bromide analogues, hence their difficult synthesis. The structural constraints that limit stability, on the other hand, can be much relieved in layered, organic-inorganic perovskites. Following this line of thought, we report here a successful fast precipitation route to iodide layered (CnH(2n+1)NH3)4AgBiI8 (n = 10, 12, and 14) double perovskites that borrow concepts from the synthesis of colloidal nanocrystals. X-ray diffraction studies revealed for these compounds a monoclinic
crystal structure containing edge-sharing alternated [AgI6] and [BiI6] octahedra. These materials have experimental band gaps of 2.1 eV, as also corroborated by theoretical calculations. We have also investigated their phase transitions by thermal analysis and temperature-dependent diffraction and found them to be similar to their lead-based layered perovskite counterparts.
Read the full abstract ▾
All authors Pascal Rusch, Ann Mary Antony, Meenakshi Pegu, Meysoun Jabrane, Gabriele Saleh, Arghyadeep Garai, Aswin Asaithambi, Simone Lauciello, Sergio Marras, Serena De Negri, Pavlo Solokha, Liberato Manna
Superconductivity
Reply to "Threefold error in the reported zero-field cooled magnetic moment of single crystal $La_2SmNi_2O_7$ (arXiv: 2602.23240)"
Feiyu Li, Zhenfang Xing, Di Peng et al. (+24 more)
We respond to the critique by Aleksandr V. Korolev and Evgeny F. Talantsev on the superconducting phase fraction ($f$) calculations in Li et al. Nature 649, 871-878 (2026). First, the weak upturn in the low-temperature tail of our data has been confirmed to originate from the background, and the paramagnetic Meissner effect is absent in our case; thus, field-cooled (FC) data can be used for superconducting phase fraction calculations. Second, demagnetization effect must be calculated based on the actual measured moment as a function of $f$, which has been well-established and routinely employed in the superconductivity community. In contrast, Korolev and Talantsev treated the demagnetization field as a constant; thus, their calculation underestimates $f$ by a factor of $(1-N\chi_{meas})(1-N)$. This factor is close to 1/3, given $N$ = 0.849, $\chi_{meas}$ = -1.313 in our study, which explains the origin of their deviated result (nearly three times smaller than our results). Third, our sample is a homogeneous high-quality bulk single
crystal, evidenced by various techniques, making the existence of multiple discrete superconducting regions highly unlikely. We conclude that the superconducting phase fraction calculations reported in Li et al. Nature 649, 871-878 (2026) are not invalidated by the analyses presented in Korolev et al. arXiv: 2602.23240 (2026).
Read the full abstract ▾
All authors Feiyu Li, Zhenfang Xing, Di Peng, Jie Dou, Ning Guo, Liang Ma, Yulin Zhang, Lingzhen Wang, Jun Luo, Jie Yang, Jian Zhang, Tieyan Chang, Yu-Sheng Chen, Weizhao Cai, Jinguang Cheng, Yuzhu Wang, Yuxin Liu, Tao Luo, Naohisa Hirao, Takahiro Matsuoka, Hirokazu Kadobayashi, Zhidan Zeng, Qiang Zheng, Rui Zhou, Qiaoshi Zeng, Xutang Tao, Junjie Zhang
Materials Science
Structural Evolution during Reversible Halogen Intercalation into WTe2: Commensurate-Incommensurate WTe2I and Multistage WTe2Brx (x = 0.5, 1.0 and 1.25)
Patrick Schmidt, Carl P. Romao and Hans-Jürgen Meyer
Halogen intercalation into the layered material tungsten ditelluride (WTe2) provides a unique pathway to tune its structural and electronic properties. In this study, we detail the synthesis and characterization of the new bromine-intercalated phases WTe2Brx (x = 0.5, 1.0, and 1.25), and reinvestigate the iodine-intercalated analogue, WTe2I. A defining feature of the bromine system is its rapid and reversible "breathing" behavior at room temperature, allowing guest molecules to be absorbed or released from the van der Waals gaps under ambient conditions. Structural analysis shows that the bromine-poor phase WTe2Br0.5 crystallizes in the orthorhombic space group Pmmn, thereby maintaining a uniform stacking sequence. In contrast, the bromine-rich WTe2Br1.25 phase (space group Imm2) adopts an architecture where two distinct types of bromine layers alternate between the host layers. For the iodine system, the compound WTe2I exhibits both incommensurate and commensurate (3+1)D modulated variants in the superspace group P21/m({\alpha}0{\gamma})00. In the commensurate polytype, the structural modulation locks into a rational vector, q = (1/2, 0, 1/6), which can be described also as a 3D supercell. Electronic structure calculations show WTe2Br0.5 and commensurately modulated WTe2I to be metals with flat bands at the
Fermi energy arising from the intercalation. These findings demonstrate the unusual stability and structural flexibility of anionic intercalation in a transition metal dichalcogenides.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from math.PR
An exactly solvable evaporation-deposition PCA with long-distance interactions
Arvind Ayyer and Moumanti Podder
We consider a probabilistic cellular automaton (PCA) of evaporation-deposition on the one-dimensional
lattice having $n$ sites with periodic boundary conditions, in which each site, during each epoch, can be in one of two states: $0$ and $1$. Fix a positive integer $m\geqslant 2$. There are two types of transitions at each discrete time, which are as follows: (i) the first site in every contiguous block of $m$ $0$s becomes a $1$ with probability $p_1$, and (ii) the first site in every contiguous block of $(m-1)$ $0$s followed immediately by a $1$ also becomes a $1$ with probability $(1-p_2)$. As in a PCA, all of these transitions occur simultaneously. We show that the resulting discrete-time Markov chain is ergodic, and we give an explicit formula for its limiting distribution, the partition function and the density. We also propose necessary and sufficient conditions for this Markov chain to be reversible. For $m=2$, we provide a fully analytical expression for the free energy of this model.
Read the full abstract ▾
Soft Condensed Matter
Self-Buckling of Pressurized Cylindrical Tubes
Morten Opstrup Andersen, Nikolaj Tønner Osvald Olsen, Diksha Bhola et al. (+4 more)
We investigate the buckling of hollow cylindrical tubes subject to their own weight and internal pressure, inspired by the columnar
cells of the palisade mesophyll in dicotyledon leaves which resemble pressurized cylindrical tubes. When the internal pressure in the cylinder is equal to the outside pressure, the problem is usually termed self-buckling, which has been studied extensively for solid rods, hollow cylinders, and thin cylindrical shells. Specifically, we perform FEM simulations and desktop-scale experiments to determine the instability thresholds for different geometrical parameters. We first test our models against self-buckling results without pressure for solid rods and hollow cylindrical tubes, and then proceed to determine the critical buckling pressure for a set of material and geometrical parameters. We find that positive internal pressures can stiffen cylinders that are unstable under their own weight, leading to an effective Young's modulus that we show scales linearly with the applied pressure. On the contrary, cylinders that are stable under self-weight, buckle under a negative pressure, resembling classical results on pressure-induced ring buckling. Our findings offer new insights on the interplay between
gravity and pressure for the mechanical instability of hollow cylindrical tubes, which we hope will be useful for the study of both engineering and biological structures under similar loads.
Read the full abstract ▾
All authors Morten Opstrup Andersen, Nikolaj Tønner Osvald Olsen, Diksha Bhola, Aleca Borsuk, Craig Brodersen, Anja Geitmann, Matteo Pezzulla
Mesoscale and Nanoscale Physics
Topological-Mass Control of an Emergent Kondo Scale in an Interacting SSH Chain
Ryosuke Yoshii and Rio Oto
Topological bound states emerging at domain walls of dimerized chains provide a robust platform for exploring correlation effects beyond single-particle physics. When such a
soliton state is coupled to a metallic substrate, local Coulomb interactions can give rise to Kondo screening. Here we demonstrate analytically and numerically that, in an interacting Su-Schrieffer-Heeger (SSH) chain, the Kondo temperature is directly controlled by the topological mass that governs the bulk gap. Near the topological transition, the Kondo scale collapses linearly with the mass parameter while retaining its exponential sensitivity to hybridization. This establishes a minimal mechanism by which a bulk topological parameter quantitatively determines an emergent many-body energy scale. Our results clarify the strong configuration dependence of
soliton-induced Kondo signatures observed in
graphene nanoribbon systems on Au(111) and provide experimentally testable predictions for scanning tunneling spectroscopy.
Read the full abstract ▾
Soft Condensed Matter
The origin of complex behavior of liquid carbon: an insight from computer simulation
Yu. D. Fomin
In the present paper we perfomrm molecular dynamics simulation of
liquid carbon with a machine-learning potential GAP-20. We show that within the framework of this model carbon demonstrates a relatively low critical temperature, which can affect the results of experimental measurements of melting point of graphite.
Read the full abstract ▾
Soft Condensed Matter
Modeling of polymer phase transition from crystalline to conformationally disordered phase
V. V. Atrazhev, D. V. Dmitriev and V. I. Sultanov
A physics-based analytical model describing the phase transition from crystalline to conformationally disordered (condis) crystalline phase is developed. In the model, the free energy is written as a function of temperature and the
lattice parameter (mean distance between neighboring chains). It consists of two contributions: elastic and conformational. The elastic contribution describes the interaction between neighboring chains, while the conformational part takes into account the conformation of one chain inside the potential tube, formed by the neighboring chains. To verify this approach, polyethylene - the simplest
polymer possessing the condis phase - was chosen as a modeling object. Previous experiments and molecular dynamics simulations show that the typical conformation of a
polymer chain in a crystalline phase consists mainly of trans dihedrals and a small fraction of gauche dihedrals, which can be considered as defects of the crystalline
lattice. These defects displace the chain inside the tube thus increasing the potential energy. The energy required to form such a defect decreases rapidly with increasing distance between neighboring chains. This leads to a first-order phase transition at a certain temperature to the condis phase, in which distance between neighboring chains is large and a fraction of gauche dihedrals is high. This physical picture of the phase transition is described by the proposed analytical model, the parameters of which were calibrated against the results of molecular dynamics simulations for atmospheric pressure. The model predictions for the pressure of 500 atm and 1000 atm are in perfect agreement with the results of molecular dynamics simulations.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from quant-ph
Spin stiffness and resilience phase transition in a noisy toric-rotor code
Morteza Zarei and Mohammad Hossein Zarei
We use a
quantum formalism for the partition function of the classical $XY$ model to identify a resilience phase transition in the zero-syndrome postselected sector of a noisy toric-rotor code. To this end, we consider a logical state of toric-rotor code under phase-shift noise described by a von Mises probability distribution. We then show that the fidelity of the noisy state with respect to the initial logical state is proportional to the partition function of the $XY$ model, such that a Kosterlitz-Thouless phase transition at a critical temperature $T_c$ corresponds to a resilience phase transition at a critical width $\sigma_c$. To characterize this transition, we map the
spin stiffness of the $XY$ model to a topological order parameter $0\leq \lambda \leq 1$, which quantifies the intrinsic resilience of the code to decoherence within the zero-syndrome subspace. We show that the initial logical state exhibits partial resilience to noise for widths less than $\sigma_c \approx 0.89$, where $\lambda$ satisfies $0< \lambda <1$ and drops discontinuously to zero at $\sigma_c$. We further discuss the implications of our results for postselected
quantum error correction in the toric-rotor code in higher dimensions. Our work shows that the
quantum formalism for partition functions provides a mathematically rigorous framework for studying noisy continuous-variable
quantum codes.
Read the full abstract ▾
Mesoscale and Nanoscale Physics · Cross-listed from physics.chem-ph
Molecular Electron Transfer in Optical Cavities: From Excitonic to Vibronic Polaritons
Takumi Hidaka, Tomohiro Fukushima and Nguyen Thanh Phuc
Strong coupling between molecular excitations and quantized electromagnetic fields in optical cavities provides a powerful means to control the physical and chemical properties of molecular systems. Here, we study electron transfer (ET) dynamics in cavity-coupled molecules using the numerically exact hierarchical equations of motion (HEOM) method, which captures nonperturbative and non-Markovian effects beyond standard perturbative theories. We identify distinct resonance and collective effects associated with polariton formation and show that the ET rate saturates in the strong-coupling regime, a feature not captured by perturbative approaches. We further extend the cavity-modified ET model by incorporating the
nuclear-coordinate dependence of molecular electric dipole moments, which gives rise to a three-body interaction involving molecular electronic and vibrational degrees of freedom and cavity
photons. This vibronic polariton formation leads to non-monotonic, oscillatory dependencies of the ET rate on the light-matter coupling strength and cavity frequency, which we attribute to
quantum interference among multiple transfer pathways. These findings establish cavity-modified electron transfer as a multichannel
quantum process governed by the interplay of electronic, vibrational, and photonic degrees of freedom.
Read the full abstract ▾
Materials Science
kALDo 2.0: Scalable Thermal Transport from First Principles and Machine Learning Potentials
Giuseppe Barbalinardo, Zekun Chen, Dylan Folkner et al. (+5 more)
We introduce kALDo2.0, an open-source Python package for computing vibrational, elastic, and thermal transport properties of solids from first principles and machine-learned interatomic potentials. Building on the anharmonic
lattice dynamics (ALD) framework, kALDo2.0 provides efficient CPU and GPU-accelerated implementations of the Boltzmann transport equation (BTE) for
crystals and the quasi-harmonic Green-Kubo (QHGK) method. QHGK extends thermal transport predictions beyond
crystals to disordered materials, including glasses,
alloys, and complex nanostructures. kALDo2.0 introduces native integration with modern machine-learned potentials (MLPs), enabling thermal transport workflows that combine the accuracy of first-principles methods with the scalability of classical force fields. It also features comprehensive support for temperature-dependent effective potentials workflows, flexible storage backends for large-scale calculations, and advanced quantification of anharmonicity. The software seamlessly interfaces with electronic structure codes (
Quantum ESPRESSO, VASP), molecular dynamics packages (LAMMPS), and MLPs (ACE, NEP, MACE, MatterSim, Orb), enabling thermal transport studies from 0 K to finite temperatures. kALDo2.0 implements multiple BTE solution strategies and essential physical corrections, including isotopic scattering and non-analytical terms for polar materials. A modular Python architecture with lazy evaluation and multiple storage formats (ASCII, NumPy, HDF5) enables simulations of systems containing up to tens of thousands of atoms. This paper describes the theoretical framework, implementation details, software architecture, and validation examples demonstrating kALDo2.0's capabilities for studying complex materials, including halide perovskites with strong anharmonicity and polar
oxides requiring long-range electrostatic corrections.
Read the full abstract ▾
All authors Giuseppe Barbalinardo, Zekun Chen, Dylan Folkner, Bohan Li, Nicholas W. Lundgren, Nathaniel Troup, Alfredo Fiorentino, Davide Donadio
Superconductivity
Unveiling the superconducting scenario in multiphase superconductor CeRh$_2$As$_2$ from space-group symmetry analysis and DFT calculations
V.G. Yarzhemsky, E.A. Teplyakov, S.V. Eremeev et al. (+1 more)
Despite of the low transition temperature, the recently identified
superconductor CeRh$_2$As$_2$ has garnered significant interest due to its unique
symmetry and
magnetic characteristics, particularly the existence of two superconducting (SC) phases under a
magnetic field, one of which exceeds the Pauli-Clogston limit. The field-induced transition from a low-field even-parity state to a high-field odd-parity state is usually described as a singlet-triplet transition. However, it is uncommon for a single compound to exhibit both triplet and singlet SC scenarios. The aim of this paper is to investigate the possibilities of
symmetry changes in the SC state without a change of
spin multiplicity. To this end, we construct the SC order parameter based on Anderson pair functions, considering the phase winding within the
symmetry of the point group $D_{4h}$ and the
magnetic group $4/mm^{\prime }m^{\prime}$. It was found that two triplets with opposite-
spin and equal-
spin pairing states of
symmetry $E_{1u}^{\prime +}$, are nodeless but exhibit distinct internal structures and may be associated with low-and high-field phases. Additionally, nontrivial Cooper pairing resulting from the non-symmorphic structure of the space group was examined, particularly in the case where the
Fermi surface intersects with the boundaries of a Brillouin zone (BZ). It was determined that at the X point, triplet pairs are even, while singlet pairs can be either even or odd. Furthermore, at the X point, pair density waves that alter phase by $\pi$ at the atomic centers linked by
lattice translations are also feasible. To explore the possibility of such scenarios, precise DFT calculations of the band structure were performed, revealing the contribution of Ce $4f$ electrons to the states at the
Fermi level. Thus, the even-odd transition can take place in a triplet scenario at
symmetry points of a BZ.
Read the full abstract ▾
All authors V.G. Yarzhemsky, E.A. Teplyakov, S.V. Eremeev, E.V. Chulkov
Mesoscale and Nanoscale Physics
Real-time Amplitude and Phase Estimation of AC Fields with Diamond Spins
Christopher T.-K. Lew, Samuel A. Wilkinson, Nicholas Gillespie et al. (+3 more)
Nitrogen-vacancy centers in diamond have been shown to be capable of detecting AC
magnetic fields with high sensitivity, spectral resolution, and spatial resolution. However, most studies so far have focused on the regime of time-averaged or time-correlated measurements, while little
attention has been paid to the single-shot regime. Here we show that the amplitude and phase of an AC field can be retrieved from a single pair of two consecutive measurements. We demonstrate this concept by measuring a 4 MHz AC field with a per-shot amplitude and phase sensitivity of 78 nT and 63 mrad, respectively, at a temporal resolution of 320 us. We also investigate the effects and quantify the errors resulting from probe frequency detunings, as well as operating in the strong field regime. Moreover, we showcase the ability of the measurement protocol to dynamically change the probe frequency in real-time. This work advances the use of NV centers for real-time measurements of AC
magnetic fields.
Read the full abstract ▾
All authors Christopher T.-K. Lew, Samuel A. Wilkinson, Nicholas Gillespie, Brant C. Gibson, David A. Broadway, Jean-Philippe Tetienne
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
Symmetry-breaking bifurcation of coupled topological edge states
Rujiang Li, Letian Xu, Muhammad Imran et al. (+3 more)
We propose that the
symmetry-breaking bifurcation of coupled topological edge states (CTESs) can be used as a general principle for achieving spontaneous
symmetry breaking (SSB) in a nonlinear topological
lattice. Using an optical resonator array composed of two Su-Schrieffer-Heeger (SSH) chains as an example, we find that as the nonlinearity strength increases, the symmetric CTESs undergo a supercritical bifurcation. Beyond the critical threshold, the originally stable symmetric state becomes unstable, leading to the formation of a pair of stable asymmetric states. Both sides of the symmetric CTESs exhibit sublattice polarization, while the side of the asymmetric CTESs that is predominantly occupied demonstrates stronger sublattice polarization. We further find that as interchain coupling increases, the frequency range for stable CTESs expands, while the frequency range for stable asymmetric CTESs decreases. Our work provides a universal mechanism for realizing SSB in nonlinear topological
lattices.
Read the full abstract ▾
All authors Rujiang Li, Letian Xu, Muhammad Imran, Wencai Wang, Yongtao Jia, Ying Liu
Superconductivity
Inverse Isotope Effect in the Ternary Perovskite Hydride SrPdH/D$_{2.9}$: A Signature of Quantum Zero-Point Fluctuations
Wencheng Lu, Mihir Sahoo, Roman Lucrezi et al. (+9 more)
Guided by first-principles calculations, we demonstrate superconductivity in the ternary perovskite hydride SrPdH$_{3-x}$, synthesized at low pressure. Structural characterization via
neutron diffraction reveals the near-stoichiometric composition SrPdD$_{2.9(2)}$ with 96% deuterium site occupancy. Subsequent transport and
magnetic susceptibility measurements establish onset superconducting transitions at $T_\text{c} = \SI{2.1}{K} $ (H) and $T_\text{c} = \SI{2.2}{K} $ (D), exhibiting an inverse isotope effect that our first-principles calculations attribute predominantly to
quantum zero-point motion. The excellent agreement between theory and experiment with respect to thermodynamic stability and superconducting properties provides important validation for theory-guided
superconductor discovery. This work establishes superconductivity in the perovskite hydride structural prototype – expanding the limited family of experimentally realized ternary hydride
superconductors – and demonstrates the importance of
quantum nuclear motion on the accurate theoretical treatment of low-pressure hydride
superconductors.
Read the full abstract ▾
All authors Wencheng Lu, Mihir Sahoo, Roman Lucrezi, Michael J. Hutcheon, Shubham Sinha, Pedro N. Ferreira, Chris J. Pickard, Qiang Zhang, Matthew N. Julian, Rohit P. Prasankumar, Christoph Heil, Timothy A. Strobel
Soft Condensed Matter
Stress Relaxation Driven by Elementary Plastic Events in Non-Ageing Liquid Foams
F. Schott, B. Dollet, C. M. Schlepütz et al. (+5 more)
Liquid foams are archetypal athermal amorphous solids whose elasticity arises from the jamming of densely packed bubbles. We investigate the stress relaxation of non-ageing
liquid foams following flow cessation, using fast X-ray tomo-rheoscopy. Thanks to in situ, time-resolved measurements, we uncover robust linear affine relationships between shear stress, plastic activity, and coordination number throughout the relaxation toward a residual stress state below the yield value. In contrast to previous studies on amorphous solids, we observe an exponential relaxation governed by the duration of individual plastic events, rather than by cascades of correlated ones associated with much longer, shear-rate-dependent timescales or power-law relaxations. Our results provide new insight into the microscopic mechanisms governing the time
evolution of stress in jammed amorphous solids.
Read the full abstract ▾
All authors F. Schott, B. Dollet, C. M. Schlepütz, C. Claudet, S. Gstöhl, R. Mokso, S. Santucci, C. Raufaste
Materials Science
Equilibrium kink-like torsion deformation of a magnetoactive elastomer under a magnetic field
Yu. I. Dzhezherya, A. V. Kyryliuk, S. V. Cherepov et al. (+4 more)
A novel effect involving the formation of a stable kink-like torsion deformation in a magnetoactive elastomer (MAE) beam subjected to a uniform
magnetic field is theoretically predicted and experimentally confirmed. The phenomenon was demonstrated using an elastomer beam containing soft
magnetic carbonyl iron microparticles within a silicone
matrix. The torsion kink acts as a transition boundary between two undeformed homogeneous states of the beam. We show that the elastic moment is compensated by a magnetoelastic moment in the kink region, where the local magnetization of the beam is non-collinear to the applied
magnetic field due to shape anisotropy. It is established that within the kink region, the MAE beam exists in a non-uniformly elastically deformed, low-
symmetry magnetic state. Outside the kink, the beam's magnetization is collinear with the
magnetic field, corresponding to an undeformed, high-
symmetry homogeneous
magnetic state.
Read the full abstract ▾
All authors Yu. I. Dzhezherya, A. V. Kyryliuk, S. V. Cherepov, Yu. B. Skirta, S. O. Reshetniak, S. M. Ryabchenko, V. M. Kalita
Superconductivity
Intrinsic translational symmetry-breaking charge stripes in underdoped iron pnictides
Qiang-Jun Cheng, Cong-Cong Lou, Yong-Wei Wang et al. (+4 more)
Despite being well established in cuprates, an intrinsic translational
symmetry-breaking charge order has not been clearly identified in iron-based
superconductors. Using spectroscopic-imaging scanning tunneling microscopy on epitaxial Ca(Fe1-xCox)2As2 (x = 0 ~ 0.055) thin films, we observe smectic, near-commensurate charge-stripe order in the underdoped regime that intervenes between the nematic parent phase and optimally doped superconductivity. Distinct from the bidirectional checkerboard-like order in cuprates, these charge stripes are unidirectional along the
antiferromagnetic Fe-Fe bond direction and are accompanied by a van Hove singularity near the
Fermi level, inherited from the
Fermi surface reconstruction driven by intertwined
antiferromagnetic and nematic correlations. Both local and global suppression of the charge-stripe instability enhance superconductivity, tunable via epitaxial strain and Co doping. These results establish charge-stripe order as an intermediate electronic phase in iron pnictides and reveal a coherent pathway from nematicity to superconductivity. Our findings highlight charge ordering as a unifying element across different families of high-temperature
superconductors.
Read the full abstract ▾
All authors Qiang-Jun Cheng, Cong-Cong Lou, Yong-Wei Wang, Ze-Xian Deng, Xu-Cun Ma, Qi-Kun Xue, Can-Li Song
Superconductivity
High-pressure stabilization of Mg2IrH7: Structural proximity to high-Tc superconductivity
Shubham Sinha, Wencheng Lu, Mads F. Hansen et al. (+14 more)
Mg$_2$IrH$_6$ is a metastable complex metal hydride with a predicted superconducting transition temperature as high as 170 K at ambient pressure. Following the synthesis of isomorphic, insulating Mg$_2$IrH$_5$ at low pressure, higher-pressure studies were conducted to investigate the phase behavior and compound formation in this system. X-ray diffraction and Raman spectroscopic measurements indicate that cubic Mg$_2$IrH$_7$ is stabilized above ca. 40 GPa and coexists with a related hexagonal hydride with likely composition near Mg$_2$IrH$_5$. Electrical transport measurements show that the cubic Mg$_2$IrH$_7$ is insulating, in agreement with ab initio predictions, and persists during room-temperature decompression until $\sim$20 GPa before reverting back to the cubic Mg$_2$IrH$_5$. The experimental results confirm ground-state structure predictions in the Mg-Ir-H system, and the formation of two nearly identical phases with surrounding compositions opens new opportunities to access superconducting Mg$_2$IrH$_6$ through non-
equilibrium processing pathways.
Read the full abstract ▾
All authors Shubham Sinha, Wencheng Lu, Mads F. Hansen, Michael J. Hutcheon, Trevor W. Bontke, Lewis J. Conway, Kapildeb Dolui, Chris J. Pickard, Christoph Heil, Piotr A. Guńka, Stella Chariton, Vitali Prakapenka, Liangzi Deng, Ching-Wu Chu, Matthew N. Julian, Rohit P. Prasankumar, Timothy A. Strobel
Soft Condensed Matter
Universal Scaling of Macroscopic Softening and Microscopic Scission in Phantom Chain Networks
Yuichi Masubuchi
This study demonstrates that the apparent complexity of fracture in phantom-chain
polymer networks is fully decoupled into two universal master curves: (i) macroscopic softening governed by the absolute stretch, and (ii) microscopic scission governed solely by the relative stretch. Using the previously proposed network mechanics model, an analytical expression has been derived to quantitatively capture the nonlinear growth of microscopic damage. Combining the softening exponent with
polymer-solution scaling yields a simple novel relationship, $\sigma_{nb} / G \propto (c / c^* )^{(-1/3)}$, where $\sigma_{nb}$ is the nominal broken strength, $G$ is the initial shear modulus, $c$ is the prepolymer concentration, and $c^*$ is its overlapping threshold.
Read the full abstract ▾
Mesoscale and Nanoscale Physics · Cross-listed from quant-ph
Perfect transmission of a Dirac particle in one-dimension double square barrier
Xu Zhang and Qiang Gu
Dirac particles can undergo perfect transmission through a sufficiently high potential barrier in the Klein zone. Although the perfect Klein tunneling (often referred to as the Klein paradox) is similar to the non-relativistic resonant transmission which occurs only when the kinetic energy exceeds the barrier, the underlying mechanism is believed to be fundamentally distinct. In this work, we show that for the relativistic double-barrier model the perfect-transmission curve can pass continuously from the above-barrier zone to the Klein zone. Additionally, in the Klein zone, perfect transmission occurs even for subcritical barrier heights, supported by both bound-state analysis and wave-packet dynamics. These findings suggest a connection between perfect Klein tunneling and resonant transmission, and provide new insights into the physical nature of the Klein paradox.
Read the full abstract ▾
Materials Science
High sub-bandgap response and fast switching enabled by thermal quenching in carbon-doped semi-insulating GaN
Jiahao Dong, Auditee Majumder Momo, Austin Fehr et al. (+6 more)
Carbon-doped GaN is a promising material for sub-bandgap triggered optical switches. When incorporated in GaN, carbon introduces deep compensating centers that enable defect-mediated extrinsic photoconductivity. Here, we investigate the optical responsivity and switching kinetics of semi-insulating carbon-doped GaN actuated by sub-bandgap blue illumination. A high ON/OFF ratio exceeding $\mathrm{10^7}$ is achieved under low-irradiance 405-nm excitation. Temperature-dependent transient measurements reveal that the photocurrent decay is thermally quenched above a crossover temperature of ~300 K. This behavior is attributed to hole-emission-assisted recombination. The extracted activation energies vary across samples; a commonly observed value of ~0.83 eV is attributed to the $\mathrm{C_N}$ defect. Notably, when heating above the crossover temperature, thermal quenching accelerates the photocurrent decay by up to a factor of five, enabling significantly faster switching.
Read the full abstract ▾
All authors Jiahao Dong, Auditee Majumder Momo, Austin Fehr, Sanam SaeidNahaei, Pramod Reddy, Ronny Kirste, Zlatko Sitar, Ramón Collazo, Selim Elhadj
Materials Science
Ab initio electronic conductivity of Fe-bearing post-perovskite
Yihang Peng, Yupei Zhang, Shuai Zhang et al. (+5 more)
The electrical conductivity of high-pressure silicates profoundly influences the interior dynamics of rocky
planets. Employing the Kubo-Greenwood formalism, we perform ab initio calculations of electronic conductivity in Fe-bearing post-perovskite under super-Earth mantle conditions, up to 4000 K and 500 GPa. Electronic structures are obtained via many-body perturbation theory, incorporating dynamical screening and correlations among localized Fe-3d orbitals. In contrast to (Fe,Mg)O, for which metallization has been reported at comparable conditions, our results indicate that post-perovskite with Earth-like Fe contents is unlikely to metallize in super-Earth mantles via band-gap closure, yielding negligible low-frequency conductivity. Any substantial conductivity would require non-electronic mechanisms, such as thermally activated small-polaron hopping, which fall beyond the scope of band conduction.
Read the full abstract ▾
All authors Yihang Peng, Yupei Zhang, Shuai Zhang, Chenxing Luo, Donghao Zheng, Nelson Naveas, Xifan Wu, Jie Deng