Materials Science
Linking Calendar and Cycle Ageing in Lithium-Ion Batteries through Consistent Parameterisation of an Electrochemical-Thermal-Degradation Model
Ganesh Madabattula
Parameterisation of coupled degradation mechanisms in lithium-ion batteries is a major challenge. Interactions between the mechanisms depend on usage conditions: C-rate, rest state-of-charge (SoC), depth-of-discharge (DoD) and temperature. This work presents a framework to consistently parameterise key degradation modes–solid-electrolyte interphase (SEI) growth, lithium plating, and active material loss in both electrodes–using insights derived from degradation mode analysis data. The work predicts capacity fade trajectories of a NMC-based lithium-ion
cell under both calendar and combined calendar-cyclic ageing, using a P2D electrochemical-thermal-degradation model. The work predicts state-of-health (SoH), remaining-useful-life (RUL) and internal degradation modes of the
cell–under 81 combinations of temperature (10$^o$C, 25$^o$C, 40$^o$C), C-rate (0.1 C, 0.3 C and 1.0 C), rest SoC (10%, 60%, and 100%) and DoD (50%, 70%, and 90%)–using PyBaMM. The predicted cycle-life varies between 0.8 to 14 years to reach 75% of SoH. The work provides mechanistic insights into competing effects between calendar and cyclic ageing, during cycling. The model demonstrates sub-linear, linear, and sup-linear/accelerated capacity fade based on the usage conditions. The simulated
dataset for all the cases is made available.
Read the full abstract ▾
Materials Science
Phase Equilibria of the Al-Ti-Nb-Zr-Ta System
Jiří Kozlík, František Lukáč, Mariano Casas-Luna et al. (+8 more)
Phase
equilibria in the Al-Ti-Nb-Zr-Ta refractory complex concentrated
alloy system were investigated using a high throughput experimental approach. A pseudo-ternary section of the quinary compositional space was prepared by a honeycomb type powder metallurgy design, consolidated by spark
plasma sintering and subsequently homogenized at 1400 {\deg}C for 168 h. Phase constitution and chemical partitioning were characterized by SEM/EDS, XRD, EBSD, and TEM, supported by a custom EDS phase clustering workflow.
Equilibrium microstructures consisting primarily of BCC, B2, and secondary phases were identified across the sampled compositions, with nanoscale precipitates forming in Zr and Ta rich regions. Measured phase compositions were compared with CALPHAD predictions, revealing both agreements and systematic deviations linked to CALPHAD database limitations. The results provide new experimental insight into phase stability and microstructural trends in Al-Ti-Nb-Zr-Ta
alloys and demonstrate the effectiveness of high throughput combinatorial approaches for mapping complex multicomponent systems.
Read the full abstract ▾
All authors Jiří Kozlík, František Lukáč, Mariano Casas-Luna, Jozef Veselý, Eliška Jača, Kateřina Ficková, Stanislav Šašek, Kristína Bartha, Adam Strnad, Tomáš Chráska, Josef Stráský
Materials Science
The hidden ferroelectric chiral ground state of silver niobate
Safari Amisi, Fernando Gómez-Ortiz, Eric Bousquet et al. (+1 more)
Silver niobate is a conventional perovskite
oxide compound, known to exhibit a rich polymorphism. Although often classified as antiferroelectric, its low-temperature structure remains unclear. Here, first-principles calculations reveal a previously overlooked and unusual rhombohedral ferroelectric phase with $R3$
symmetry that emerges as the thermodynamic ground state despite its almost degenerate energy and close energetic competition with previously proposed structures. Remarkably, this phase is structurally
chiral, with chirality emerging improperly from the coupling between polarization and in-phase rotations of the oxygen octahedra along [111], producing a ferri-
chiral state with incomplete cancellation of local
chiral motifs. As a consequence, the phase exhibits significant natural optical activity comparable to that of quartz. Although energetically favored, its experimental observation may be hindered by kinetic limitations, potentially contributing to the ongoing controversy surrounding the low-temperature structure of silver niobate.
Read the full abstract ▾
All authors Safari Amisi, Fernando Gómez-Ortiz, Eric Bousquet, Philippe Ghosez
Materials Science
The effect of pressure in the crystal and magnetic structure of FeWO4
Oscar Fabelo, Javier Gonzalez-Platas, Stanislav Savvin et al. (+2 more)
The temperature dependence of the structural and
magnetic properties of wolframite-type FeWO4 were studied in situ by high pressure
neutron diffraction.
Neutron diffraction measurements were performed at the XtremeD instrument at the Institut Laue Langevin up to a maximum pressure of 8.7(4) GPa and a minimum temperature of 30.0(5) K. The diffraction data were analyzed via Rietveld refinements. We found that despite of producing a contraction of 5% of the volume, the maximum pressure applied in this study does not modify the Shubnikov space group below
magnetic order. However, the orientation of
magnetic moments and the Néel temperature, are slightly modified with the pressure, which is expected according to the preexistent understanding of magnetism in wolframites. We also determined a pressure-volume equation of state of FeWO4 at 300 K, which is compared with previous X-ray diffraction studies and density-functional theory calculations.
Read the full abstract ▾
All authors Oscar Fabelo, Javier Gonzalez-Platas, Stanislav Savvin, Pablo Botella, Daniel Errandonea
Statistical Mechanics
G. Medoš and L. Vidmar
While the eigenstate
entanglement entropy has been extensively studied for fermionic systems, much less is known about bosonic systems. Here, we study the
entanglement entropy of mid-spectrum eigenstates of Bose-Hubbard models, focusing on weakly disordered models with and without particle-number conservation, and contrasting them with the translationally-invariant model. We analyze the volume-law and O(1) contributions to the
entanglement entropy via the averages over mid-spectrum eigenstates and the corresponding distributions. We derive the volume-law coefficient of the
entanglement entropy by generalizing the mean-field approach from [Phys. Rev. Lett. 119, 220603 (2017)] to many-body systems with a tunable local bosonic cutoff, which agrees with previous analytical and numerical results from [Phys. Rev. B 110, 235154 (2024)]. We show that the volume-law contribution to the
entanglement entropy does not change upon breaking translational invariance via on-site disorder. We then numerically study the role of the subleading O(1) contribution to the
entanglement entropy. We find that, in the particle-number conserving case, it exhibits a nontrivial dependence on the particle-number density and the local bosonic cutoff, while without particle-number conservation, results suggest the emergence of a universal O(1) contribution beyond the random pure state predictions.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Topology-constrained spin-wave modes of asymmetric antibimerons and their clusters
Pavel A. Vorobyev, Daichi Kurebayashi and Oleg A. Tretiakov
Collective modes are a defining signature of coupled degrees of freedom, forming a bridge between understanding of interactions in condensed-matter systems and emergent functionality. Topological
magnetic textures provide a natural platform to realize and control such collective modes at the nanoscale. Here we theoretically identify and characterize low-energy collective
spin-wave excitations of isolated asymmetric antibimerons and their clusters in ultrathin
ferromagnetic films. We demonstrate that an isolated asymmetric antibimeron supports a discrete spectrum of localized modes, reflecting its internal degrees of freedom. When multiple asymmetric antibimerons form a cluster, inter-texture coupling leads to the splitting of these modes into $N$-fold multiplets, where $N$ denotes the number of asymmetric antibimerons. To rationalize these findings, we introduce an effective coupled-oscillator model based on meron pairs that captures the essential collective dynamics of the system. This emergent classical mechanics description reveals that the motion of asymmetric antibimeron clusters can be understood in terms of well-defined normal modes governed by
topology-constrained particle-like degrees of freedom. These results establish coupled asymmetric antibimerons as a tunable platform for
spin-wave based nano-oscillators, whose normal-mode spectrum is controllable through cluster size, thus providing a programmable set of low-lying resonances for these nano-oscillators.
Read the full abstract ▾
Superconductivity
Nonmonotonic Evolution of the Superconducting Transition Temperature and Robust Multigap Extended s-wave + s-wave Pairing in Zn-Substituted FeSe Single Crystals
Han-Shu Xu, Changhao Ding, Guanyin Gao et al. (+11 more)
We report a systematic study of superconductivity on Fe1-xZnxSe single
crystals synthesized over a broad Zn doping range (x = 0-0.023). High-quality single
crystals across all compositions range exhibit superconducting transitions, while the transition temperature Tc shows a pronounced nonmonotonic dependence on Zn doping concentration, indicating that the underlying mechanism govering Tc its
evolution cannot be explained solely by simple
impurity pair breaking alone. Magnetization and transport measurements confirm the bulk behavior of superconductivity and reveal enhanced scattering effects with Zn doping. Low-temperature specific heat is consistently described by a two-gap scenario composed of an isotropic s-wave gap and an anisotropic extended s-wave gap, whereas single-gap and alternative pairing
symmetries fail to describe the data. The nearly unchanged relative weights of the two gap components suggest the weak interband scattering induced by Zn substitution, thereby preserving multiband superconductivity. These results demonstrate the robustness of multigap superconductivity in FeSe and impose stringent constraints on candidate pairing mechanisms, highlighting the role of multiband electronic structure and anisotropic gap formation.
Read the full abstract ▾
All authors Han-Shu Xu, Changhao Ding, Guanyin Gao, Xin Zhang, Xinyu Yin, Xucai Kan, Jiaping Hu, Wen Xie, Wensen Wei, Yuxiao Hou, Keyu An, Haoxiang Li, Kaibin Tang, Yu-Yan Han
Materials Science
Effects of Compression on the Local Iodine Environment in Dipotassium Zinc Tetraiodate(V) Dihydrate K2Zn(IO3)4.2H2O
Daniel Errandonea, Robin Turnbull, Hussien H. H. Osman et al. (+8 more)
Combining X-ray diffraction with density-functional theory and electron
topology calculations we found that pressure substantially modifies the bonding in K2Zn(IO3)4.2H2O. We discovered that under compression there is a progressive change from primary covalent I-O bonds and secondary halogen I-O interactions towards O-I-O electron-deficient multicenter bonds. Because of this, iodine hypercoordination converts IO3 trigonal pyramids towards IO6 units. The formation of these IO6 units breaks the typical isolation of iodate molecules forming an infinite two-dimensional iodate network. Hypercoordination influences the hydrogen atoms too, such that multicenter O-H-O bonds are also promoted with increasing pressure. We have determined that K2Zn(IO3)4.2H2O is one of the most compressible iodates studied to date, with a bulk modulus of 22(3) GPa. The pressure-induced structural changes strongly modify the electronic structure as shown by optical-absorption measurements and band-structure calculations. The band-gap energy closes from 4.2(1) eV at ambient pressure to 3.4(1) eV at 20 GPa.
Read the full abstract ▾
All authors Daniel Errandonea, Robin Turnbull, Hussien H. H. Osman, Zoulikha Hebboul, Pablo Botella, Neha Bura, Peijie Zhang, Jose Luis Rodrigo Ramon, Josu Sanchez-Martin, Catalin Popescu, Francisco J. Manjon
Strongly Correlated Electrons · Cross-listed from hep-th
Lattice Realizations of Flat Gauging and T-duality Defects at Any Radius
Riccardo Argurio, Giovanni Galati and Nathan Godechal
We analyze non-invertible topological interfaces and defects in the two-dimensional compact
boson, focusing on the more exotic ones obtained by gauging continuous
symmetries with flat connections on a half-space. These include interfaces between mutually irrational radii and T-duality
symmetries at arbitrary
boson radius. Using the modified Villain discretization on both a Euclidean two-dimensional square
lattice and a
quantum one-dimensional chain, we show that all these topological interfaces survive discretization and give rise to non-compact edge modes localized at the defect sites. Such non-compact edge modes imply a continuous defect spectrum and an infinite
quantum dimension. In the special case of rational radii, we show how the defect action or
Hamiltonian can be modified in order to compactify the edge modes and produce more standard defects with finite
quantum dimension.
Read the full abstract ▾
Quantum Gases
Ultrafast All-Optical Switching via a Supersolid Phase Transition of Light
J. L. Figueiredo, J. T. Mendonça and H. Terças
We propose ultrafast all-optical switching exploiting the bistability between a spatially uniform
photon superfluid and a spontaneously ordered supersolid in a driven-dissipative microcavity. The key ingredient is a tunable nonlocal
photon–
photon interaction engineered by
embedding a high-mobility two-dimensional electron gas (2DEG) inside the cavity. A drift current displaces the
Fermi disk, imparting a negative region to the Lindhard interaction kernel at finite wavevectors and triggering a roton instability. The resulting bistable $S$-curve supports a write–hold–erase protocol in which short optical pulses toggle the system between branches with a switching contrast of order 120~dB in our simulations. The hysteretic ON state persists under a constant sub-threshold drive after the write pulse is removed, realizing an all-optical bistable
memory. Since the
photon field couples additively to each embedded
quantum well, stacking layers with distinct drift angles allows the roton profile to be engineered with higher-order
symmetries, imprinting richer spatial order on the supersolid and enabling nonbinary generalizations of the switch. Operating in the ultrafast, sub-fJ regime, this platform outperforms most existing all-optical switches in contrast and reconfigurability.
Read the full abstract ▾
Materials Science
Systematic Study of Machine Learning Classification Algorithms of Zeolitic Imidazolate Framework Polymorphs
Emilio Méndez, Léna Triestram, Dune André et al. (+2 more)
Zeolitic Imidazolate Frameworks (ZIFs) are a family of metal–organic frameworks that feature metal centers tetrahedrally linked to imidazole-based ligands and adopt zeolite-like
topologies. ZIFs formed by Zinc cations and imidazolate linkers exhibit a remarkable degree of polymorphism, which can be modulated by varying synthesis parameters or thermodynamic conditions (i.e., temperature and pressure). Computer simulations provide a unique way of studying these materials and their phase transitions from the microscopic standpoint, revealing their underlying molecular mechanisms. However, studying these mechanisms requires to be able to classify the phase of each molecular entity in an agnostic and automatic fashion, which is particularly challenging when the two phases involved are structurally very similar. In this work, we systematically study neural network classifiers to classify ZIF phases on-the-fly during molecular dynamics simulations. We test a variety of input features, differing both in the dimensionality and nature of the descriptors and in the kind of force field used for building the training/testing database. We reveal that even with low-dimensional descriptors the classification is highly accurate, while the use of high-dimensional descriptors leads to an even better performance. Training the classifier with configurations coming from different force fields we can remove force field bias and enhance the classifier performance and general applicability. Finally, we apply our classifiers to reveal mechanistic details of the ZIF-4-cp $\xrightarrow{}$ ZIF-4-cp-II phase transition.
Read the full abstract ▾
All authors Emilio Méndez, Léna Triestram, Dune André, François-Xavier Coudert, Rocio Semino
Materials Science · Cross-listed from quant-ph
Tantalum-Encapsulated Niobium Superconducting Resonators: High Internal Quality Factor and Improved Temporal Stability via Surface Passivation
Anas Alkhazaleh, Juan Villegas, Florent Ravaux et al. (+1 more)
Superconducting coplanar waveguide resonators are essential components in
quantum processors, where their internal quality factor (Qi) constrains
qubit coherence and readout fidelity. In niobium devices, microwave losses at millikelvin temperatures are strongly influenced by two-level systems (TLS) associated with the complex NbOx surface
oxide. To mitigate these losses, we investigate a surface-engineering approach in which Nb films are capped in situ with a thin tantalum layer to suppress Nb2O5 formation and replace the native NbOx interface with a Ta-based
oxide. We fabricate Nb/Ta
bilayer and reference Nb resonators on high-resistivity silicon using identical DC sputtering and wet etching conditions, and characterize their performance at millikelvin temperatures. Fresh Ta-encapsulated devices exhibit internal quality factors up to 2.4 x 10^6 in the near-single-
photon regime, with power dependence consistent with reduced TLS-related loss at the metal-air interface. A control Nb device fabricated under the same process shows comparatively lower Q_TLS, consistent with the beneficial effect of the Ta capping layer. Furthermore, ageing tests performed on Nb/Ta resonators after six months reveal a moderate reduction in Q_TLS relative to their initial values, yet the performance remains superior to newly fabricated Nb-only devices. These results suggest that thin Ta encapsulation enhances interface quality and contributes to improved temporal stability while remaining compatible with Nb-based fabrication workflows.
Read the full abstract ▾
All authors Anas Alkhazaleh, Juan Villegas, Florent Ravaux, Alexey Zharinov
Materials Science
Metadynamics for Vacancy Dynamics in Crystals
Kazuaki Toyoura and Shunya Yamada
We propose a metadynamics-based (MetaD-based) approach to construct the free energy surface (FES) for vacancy dynamics in
crystals. In this approach, the vacancy FES can be constructed without explicitly defining a unique vacancy coordinate by introducing a set of parameters that strongly govern the FES, which is enabled by parallel bias MetaD with partitioned families (PB-MetaDPF). In addition, the proposed approach is made more efficient and effective by multihill strategy that exploits crystallographic
symmetry. We demonstrate the validity and efficacy of the proposed approach by its applications to self-
diffusion and
impurity diffusion via monovacancies and divacancies in metallic and ionic
crystals.
Read the full abstract ▾
Soft Condensed Matter
Textiles: from twisted yarn to topology and mechanics
Elizabeth J. Dresselhaus, Sonia Mahmoudi, Lauren Niu et al. (+3 more)
While textiles have existed throughout much of human history as complex mechanical metamaterials, textile science has largely been overlooked by the physics community until recently. In this review, we consider the
symmetry,
topology, and mechanics of woven and knitted materials, showing that they represent a unique, if under-explored, corner of condensed matter. We start with the basic construction and elementary mechanical model of spun yarn, reviewing recent developments twisted bundle structures. We then introduce woven and knitted fabrics as materials with layer
symmetries that can be topologically characterized as
knots and links in the thickened
torus. We finally discuss fabric mechanics and geometry, invoking recent results surrounding yarn-level and stitch-level geometry, deformations, and defect structures.
Read the full abstract ▾
All authors Elizabeth J. Dresselhaus, Sonia Mahmoudi, Lauren Niu, Samuel Poincloux, Vanessa Sanchez, Michael S. Dimitriyev
Materials Science · Cross-listed from physics.optics
Local control and lateral nanofocusing of hyperbolic phonon polaritons
Jacob T. Heiden, Haozhe Tong, Yongjun Lim et al. (+6 more)
Phonon polaritons in van der Waals
crystals enable exceptional light confinement and control over low-loss nanolight propagation. The polariton wavelength can be controlled by the
crystal geometry, isotopic composition, or surrounding environment – for which substrate engineering is particularly effective. However, existing approaches of substrate nanopatterning are binary and offer limited leverage. Here, we demonstrate local control over the wavelength of
phonon polaritons in hexagonal boron nitride by employing a sinusoidally corrugated gold surface to smoothly vary the gap between the van der Waals
crystal and metallic substrate. The nonuniform gap provides a continuous and nearly threefold local variation of the polariton wavelength across the structure, verified by near-field optical microscopy. Our platform further enables lateral nanofocusing by gradually compressing and decompressing the wavelength of propagating polaritons by a factor of around 2.5 achieved solely through substrate geometry, consistent with our local control experiments and theoretical calculations. Our results push the boundaries of substrate engineering and showcase a powerful method for precise and local tailoring of polaritonic modes.
Read the full abstract ▾
All authors Jacob T. Heiden, Haozhe Tong, Yongjun Lim, Heerin Noh, Pablo Alonso-González, Alexey. Y. Nikitin, Seungwoo Lee, Sergey G. Menabde, Min Seok Jang
Mesoscale and Nanoscale Physics
Giant resonant nonlinear THz valley Hall effect in 2D Dirac semiconductors
V. N. Ivanova, V. M. Kovalev and I. G. Savenko
We predict a
giant cyclotron resonance in the nonlinear valley
Hall response of inversion-asymmetric two-dimensional
semiconductors subjected to crossed terahertz electric and static
magnetic fields. By employing a two-band
Hamiltonian that incorporates both linear and quadratic in momentum terms, thereby capturing the essential orbital texture and broken inversion
symmetry, we develop a kinetic theory that accounts for antisymmetric skew scattering from
impurities. Solving the Boltzmann transport equation we uncover resonant photocurrents that exhibit a sharp, polarity-switching cyclotron peak and a nontrivial polarization response dictated by the underlying D3h
crystal symmetry. Our results establish a universal mechanism for frequency-selective, phase-sensitive valley current control, directly accessible in monolayer transition metal dichalcogenides. This work provides a pathway for harnessing resonant nonlinear transport in valleytronic and terahertz optoelectronic devices.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Reciprocity of Charge-Orbital-Spin Transport in Normal-Metal/Ferromagnet Heterostructures
Abhishek Erram, Akanksha Chouhan and Ashwin A. Tulapurkar
Orbital angular momentum has recently emerged as an important carrier of angular momentum in solids, offering new pathways for
spin orbitronic functionality beyond conventional
spin transport. Here, we investigate the orbital
Hall effect which generates orbital torques and their reciprocal process viz orbital pumping and the inverse orbital
Hall effect (iOHE) in non-magnet/ferromagnet
heterostructures. Using two port scattering parameter measurements on Ru/Ni, Ru/Pt/CoFeB and Co/Cu/SiO2 devices, we directly probe both orbital torque driven magnetization dynamics and orbital pumping within the same device platform. We observe that the transmission coefficients satisfy the
symmetry relations required by Onsager reciprocity, demonstrating reciprocal conversion between charge, orbital and
spin angular momenta. Our results establish orbital pumping as the reciprocal counterpart of orbital torque. Our experimental findings provide a unified framework for orbital transport phenomena.
Read the full abstract ▾
Materials Science
Selective Random Structure Search (SRSS): Unbiased Exploration of Polymorphs in Crystals
Jiexi Song, Diwei Shi, Aixian She et al. (+2 more)
Crystal structure prediction has traditionally relied on prototype-based seeding, approaches that often bias sampling toward known low-energy basins and overlook metastable polymorphs with unconventional
symmetries. Here, we introduce Selective Random Structure Search (SRSS), a high-throughput, unbiased framework designed to explore the configurational space of crystalline materials across all dimensions. SRSS combines
symmetry-constrained random generation with feature-based diversity selection and rapid relaxation and stability evaluation via universal machine-learning interatomic potentials (uMLIPs). Applied to diverse systems, including bulk system SiC and BaPtAs, 2D layered compounds NbSe2, and 1D nanotubes GaN, SRSS successfully recovers known ground states while revealing numerous previously unreported, dynamically stable polymorphs. Notable discoveries include complex cage-like SiC polytypes, low-energy BaPtAs polymorphs beyond experimental records, a semiconducting orthorhombic phase of 2D-NbSe2, and distinct armchair/zigzag GaN nanotubes. Crucially, the entire workflow operates efficiently on standard CPU resources without GPU acceleration, demonstrating that rigorous, hypothesis-free polymorph discovery is accessible even in resource-limited settings. SRSS thus establishes a robust, scalable platform for mapping the full landscape of
crystal stability, bridging the gap between exhaustive search and computational feasibility.
Read the full abstract ▾
All authors Jiexi Song, Diwei Shi, Aixian She, Chongde Cao, Fengyuan Xuan
Materials Science
Grain Growth Kinetics in (Cr,Mo,Ta,V,W)C1-{\delta} High-Entropy Carbide Ceramics
Ali Sarikhani, Gregory E. Hilmas, David W. Lipke et al. (+5 more)
Understanding grain-boundary mobility during spark
plasma sintering can enable microstructure control in high-
entropy carbides, yet quantitative grain-growth kinetics remain scarce. In this work, grain growth kinetics and densification behavior were investigated for single-phase fully dense (Cr,Mo,Ta,V,W)C1-{\delta} high-
entropy carbide ceramics. Specimens were densified by spark
plasma sintering for a constant dwell time of 10 min at temperatures between 1750 {\deg}C and 1950 {\deg}C to isolate the role of temperature on microstructural
evolution. Increasing sintering temperature produced grain growth and increased
lattice parameter, while maintaining a single-phase rock salt structure. Elemental mapping showed a progressive reduction of Ta segregation with increasing sintering temperature, suggesting enhanced chemical homogenization at elevated temperatures. Grain growth kinetics were analyzed using a normal grain growth model with an assumed growth exponent of n=3, physically reasonable for grain-boundary-controlled growth influenced by solute and vacancy pinning. Arrhenius analysis of the growth factor yielded an apparent activation energy of approximately 620 kJ mol-1, comparable to
diffusion-controlled processes in refractory transition-metal carbides. Densification curves revealed rapid consolidation prior to reaching the peak temperature followed by temperature-dominated grain coarsening. These results establish quantitative relationships between densification temperature, grain growth, and
diffusion kinetics in a carbide system, providing insight into the microstructural stability of high-
entropy, ultra-high-temperature carbide ceramics.
Read the full abstract ▾
All authors Ali Sarikhani, Gregory E. Hilmas, David W. Lipke, Douglas E. Wolfe, Stefano Curtarolo, Shen J. Dillon, Ahmad Mirzaei, William G. Fahrenholtz
Mesoscale and Nanoscale Physics · Cross-listed from physics.optics
A scalable platform for nanometer-scale quantum confinement
Christina M. Spaegele, Mehdi Rezaee, Thomas Werkmeister et al. (+8 more)
Overcoming the limitations of current nanofabrication techniques to achieve nanoscale feature sizes is essential for achieving new regimes of light-matter interactions at extreme frequencies and length scales. Here, we demonstrate a scalable nanofabrication platform capable of producing in-plane feature sizes down to 1.75 nm, pushing the boundaries of current top-down nanofabrication techniques. Using precise thickness control of atomic layer deposition (ALD) and employing widely spaced
oxide nanofins, we transform conventional ALD into a surface structuring method that produces nanolaminates with sub-10 nm periodicities over large areas. The resulting nanostructures can be used as a one-dimensional gate array to control charge carriers in two-dimensional materials. As an initial demonstration, we integrate the platform with
graphene and perform electron transport measurements. In the presence of the gate array enabled by the nanolaminate, we observe satellite Dirac peaks consistent with band-structure modulation, suggestive of
quantum-confinement effects. Our platform paves the way for exploring previously inaccessible regimes of nanoscale light-matter interactions, holding significant promise for applications in short wavelength optics, electronics, and polaritonics.
Read the full abstract ▾
All authors Christina M. Spaegele, Mehdi Rezaee, Thomas Werkmeister, Soon Wei Daniel Lim, Kailyn Vaillancourt, Joon-Suh Park, Paul Chevalier, Ido Kaminer, Philip Kim, Federico Capasso, Michele Tamagnone
Soft Condensed Matter
Theory of post-jamming rigidity in feedback-regulated cellular packings
Pawel Gniewek
Budding-
cell packings jam before all buds are mechanically constrained, so the post-jamming state is set not by the pressure $P$ alone but also by the fraction $u$ of buds that remain unconstrained. We develop a mean-field theory in these two variables for this regime. Stress feedback suppresses growth on the loaded buds, so continued growth is redirected onto the remaining free ones. As those buds are completed they add contacts that raise the excess coordination without a comparable rise in prestress. We introduce a modified Maxwell count, a bud-depletion relation, and a flux-partition argument to predict the post-jamming coordination, the density at which the reservoir of initially free buds is exhausted, and how strong feedback can stiffen the packing while generating little internal pressure. Because the added contacts raise the
rigidity while the prestress stays low, we conclude that feedback-regulated growth provides a distinct mechanism of self-rigidification.
Read the full abstract ▾
Strongly Correlated Electrons
Superconductivity and competing orders in honeycomb $t$-$J$ model: interplay of lattice geometry and next-nearest-neighbor hopping
Zhi Xu, Hong-Chen Jiang and Yi-Fan Jiang
We investigate the extended $t$-$J$ model on honeycomb
lattices with next-nearest-neighbor (NNN) electron hopping $t'$ and superexchange coupling $J'=(t'/t)^2 J$ using large-scale density-
matrix renormalization group (DMRG) simulations and slave-
boson mean-field theory (SBMFT). By systematically varying $t'$ and cylinder geometries, our DMRG results reveal several competing phases with distinct charge and superconducting (SC) properties. On YC4-0 cylinders possessing bonds lying along $\vec{e}_y$ direction, the ground state of doped models exhibits pronounced quasi-long-range $d$-wave SC with coexisting armchair-oriented stripes (a-stripe) across a broad range of $t'$. Notably, the SC Luttinger exponent has a non-monotonic dependence on $t'$, showing an optimal $t'_{op}\sim0.4$ for dominant SC. Conversely, XC cylinders host a competing long-range zigzag stripes phase without SC for $t'>0.5$, highlighting the role of boundary geometry in stabilizing distinct competing phases in DMRG. To elucidate the stability of all these competing phases in 2D limit, we employ SBMFT and identify the a-stripe as the stable configuration across most of phase diagram, with a transition to uniform nematic $d$-wave SC at large $t'$ for $\delta=1/8$. The combined results from two complementary approaches suggest a robust $t'$-induced SC phase that might remain stable in doped extended $t$-$J$ model on the honeycomb
lattice.
Read the full abstract ▾
Strongly Correlated Electrons
Evolution of crystal field and intraionic interactions in the ilmenite $A$IrO$_3$ ($A$ = Mg, Zn, Cd) and hyperhoneycomb $\beta$-ZnIrO$_3$
Yuya Haraguchi, Hiroko Aruga Katori, Kenji Ishii et al. (+1 more)
Spin-orbit Mott
insulators with the $t_{2g}^5$ electron configuration are promising platforms for the Kitaev
spin liquid, yet fine-tuning of their
crystal structures is essential to suppress non-Kitaev interactions. Here, we investigate the local electronic structures of the ilmenite iridates $A\mathrm{IrO}_3$ ($A = \mathrm{Mg}, \mathrm{Zn}, \mathrm{Cd}$) and the hyperhoneycomb $\beta\text{-}\mathrm{ZnIrO}_3$ using Ir $L_3$-edge resonant inelastic x-ray scattering (RIXS). Multiplet analysis of the RIXS spectra reveals a systematic
evolution of the
crystal field and intraionic interaction parameters upon chemical substitution at the $A$-site. We observe an enhancement of the trigonal distortion with increasing $A$-site ionic radius. This provides a microscopic explanation for the deviation from the ideal $J=1/2$ state and the
antiferromagnetic interactions identified in $\mathrm{CdIrO}_3$. Furthermore, the local multiplet parameters of ilmenite $\mathrm{ZnIrO}_3$ and hyperhoneycomb $\beta\text{-}\mathrm{ZnIrO}_3$ are found to be nearly identical, demonstrating that their different
magnetic ground states are primarily governed by their distinct
lattice structures rather than the single-ion properties. These findings establish a solid foundation for understanding how local
crystal-field distortions control the
magnetic Hamiltonian in Kitaev candidate materials.
Read the full abstract ▾
All authors Yuya Haraguchi, Hiroko Aruga Katori, Kenji Ishii, Hakuto Suzuki
Materials Science
Higher-order topological insulators in two-dimensional antiferromagnetic and altermagnetic chromium-based group-IV chalcogenides
Ruo-Yu Ning, Yong-Kun Wang, Shifeng Qian et al. (+2 more)
Based on first-principles calculations combined with theoretical analysis, we identify a family of monolayer chromium-based group-IV chalcogenides as a new class of two-dimensional (2D)
magnetic higher-order topological
insulators (HOTIs). Specifically, the CrC$X_3$ ($X=$ S, Se, Te) and CrSiS$_3$ monolayers are found to host conventional
antiferromagnetic ground states with $\mathcal{PT}$
symmetry, whereas the Janus compounds Cr$_2$C$_2$S$_3$Se$_3$ and Cr$_2$Si$_2$S$_3$Se$_3$ exhibit altermagnetic ground states. We demonstrate that all these monolayer
magnetic materials realize 2D HOTI phases, in which the nontrivial
topology is protected by
lattice $C_3$ rotational
symmetry and manifests as zero-dimensional corner states carrying quantized fractional charges. Moreover, upon inclusion of
spin-orbit coupling, these systems remain in the HOTI phase and continue to host robust corner-localized states, confirming the stability of their higher-order topological nature. Our results reveal an intrinsic connection between higher-order
topology and
magnetic order in 2D
antiferromagnetic and altermagnetic systems, identifying chromium-based group-IV chalcogenide monolayers as promising platforms for exploring higher-order topological phases and their potential relevance for future topological and spintronic applications.
Read the full abstract ▾
All authors Ruo-Yu Ning, Yong-Kun Wang, Shifeng Qian, Si Li, Wen-Li Yang
Materials Science
Pressure-Driven Activation of Semi-core p-Orbitals in Rb and Cs via Crystal-Field Splitting
Shuran Ma, Shuyang Sun, Dengyao Yu et al. (+4 more)
High-pressure unconventional oxidation states are attributed to exceptional charge transfer, which is itself induced by the differential pressure response of atomic orbital energy levels. The high oxidation states observed in heavy alkali metals (Cs, Ba, Ra) exemplify this behavior, as their semi-core p-states surpass the valence orbital levels of oxidants, e.g., the 2p-orbital of F, at high pressure. However, semi-core p-electron activation in lighter alkali metals, such as Rb, is hindered because the relative orbitals lie at intrinsically lower energies due to their smaller radii, making pressure-induced upshift challenging. We demonstrate that
crystal-field splitting of alkali-metal semi-core p-orbitals selectively elevates a portion of these states, substantially lowering the pressure threshold for their chemical activation. Here, our computations reveal that the semi-core 4p-electrons of Rb form weak metallic bonds with F in $P2_1/c$-RbBF5 at around 250 GPa, a pressure accessible in modern high-pressure experiments. Extending to Cs-B-F systems, the
crystal-field splitting drives 5p participation in Cs-F bond formation in CsBF5. These findings unveil a new paradigm for semi-core or inner-shell chemistry, providing a unifying framework for semi-core electron activation and bonding. Crucially, they establish that semi-core electrons of light main-group elements, including Rb, are accessible at experimentally feasible pressures.
Read the full abstract ▾
All authors Shuran Ma, Shuyang Sun, Dengyao Yu, Xue Cong, Yanchang Wang, Yuanzheng Chen, Zhen Liu
Materials Science
A transferable framework for structure-energy mapping of nanovoid-solute complexes: Tungsten alloys as a model system
Kang-Ni He, Xiang-Shan Kong, Jie Hou et al. (+2 more)
Understanding the structures and energetics of nanovoid-solute complexes is essential for elucidating the coupled
evolution of defects in metals. Yet their vast and complex configurational space poses a major challenge to conventional approaches. Using W-Re as a representative system, we demonstrate that solute segregation at nanovoid surfaces can be decomposed into direct nanovoid-solute interactions and nanovoid-mediated solute-solute interactions. Both are governed by local coordination motifs, with identical motifs giving nearly identical energetics. Based on first-principles data, we trained machine-learning models to map diverse local motifs to their energetics, enabling the energetics of any nanovoid-solute complex to be reconstructed from a finite set of constituent local motifs. We further developed a size-dependent configurational-search framework to efficiently identify thermodynamically stable structures, using exhaustive enumeration, simulated annealing, and greedy addition for small, medium-sized, and large complexes, respectively. This framework enabled the construction of a large database, revealed the staircase-like segregation behavior of Re, and derived a simple criterion based on Re surface coverage for rapid energy prediction across a wide size range. It also links Re segregation to vacancy-mediated nanovoid
evolution and provides
benchmarks for existing models and empirical potentials. Extensions to Os and Ta support the generality of the local-motif concept, and the predicted segregation behavior of solutes at nanovoids agrees with a range of experimental observations. This work establishes a physically transparent, accurate, and transferable framework for studying nanovoid-solute co-
evolution in metals and provides reliable energetic inputs for multiscale simulations.
Read the full abstract ▾
All authors Kang-Ni He, Xiang-Shan Kong, Jie Hou, Chang-Song Liu, Zhuo-Ming Xie
Disordered Systems and Neural Networks · Cross-listed from cs.LG
How does Chain of Thought decompose complex tasks?
Amrut Nadgir, Vijay Balasubramanian and Pratik Chaudhari
Many
language tasks can be modeled as classification problems where a large
language model (LLM) is given a
prompt and selects one among many possible answers. We show that the classification error in such problems scales as a power law in the number of classes. This has a dramatic consequence: the prediction error can be reduced substantially by splitting the overall task into a sequence of smaller classification problems, each with the same number of classes ("degree"). This tree-structured decomposition models chain-of-thought (CoT). It has been observed that CoT-based predictors perform better when they "think", i.e., when they develop a deeper tree, thus decomposing the problem into a larger number of steps. We identify a critical threshold for the degree, below which thinking is detrimental, and above which there exists an optimal depth that minimizes the error. It is impossible to surpass this minimal error by increasing the depth of thinking.
Read the full abstract ▾
Statistical Mechanics
Self-similar Dynamics in Percolation and Sandpile
Mingzhong Lu, Ming Li and Youjin Deng
Spatial self-similarity is a hallmark of critical phenomena. We study the dynamic process of percolation, in which bonds are incrementally added to an initially empty
lattice until the system becomes fully occupied. By tracking the gap – the size increment of clusters upon bond addition – and the corresponding merged cluster, we identify scale-invariant temporal patterns in both quantities throughout a large portion of the process. This reveals a form of temporal self-similarity that has not been reported before. We further establish quantitative relations between the dynamic scaling exponents and the conventional static critical exponents, which enable the determination of critical behavior without prior knowledge of the critical point. The same self-similar dynamics is observed in both bond and site percolation on
lattices and networks, and extends to other systems such as explosive and
rigidity percolation. Moreover, similar temporal scaling is found in the initial nonequilibrium
evolution of the Bak-Tang-Wiesenfeld sandpile model, suggesting a dynamic critical behavior distinct from its
equilibrium state. These results provide a unified framework for understanding critical dynamics and may find applications in a broad range of complex systems.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Antitopological magnetic textures in an antiferromagnetically coupled bilayer with frustration
Lewei Zhou, Jun Chen, Zhong Shen et al. (+2 more)
The
bilayer skyrmion composed of upper and lower tightly coupled skyrmions on two layers with completely compensated topological charges (called as anti-
topology here), has become one feasible improvement of conventional skyrmion to realize straight motion without skyrmion
Hall effect, which has aroused great interest in practical applications. The present work investigates a general model (without external
magnetic field) for the frustration-induced anti-topological
bilayer magnetic textures with rich morphologies, and discusses the modulations of key parameters on the energy barrier and the current-driven dynamics. It is revealed that the interlayer coupling plays a key role in preventing distortion, and thus helps to reach a faster velocity. This model can be realized in various frustrated
magnetic materials with antiferromagnetically coupled
bilayer, providing a helpful guidance for the material design and application of topological
magnetic textures.
Read the full abstract ▾
All authors Lewei Zhou, Jun Chen, Zhong Shen, Shuai Dong, Xiaoyan Yao