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Physics Condensed Matter

cond-mat Watch Condensed Matter

Saturday 6 December

Materials Science

Measuring the buried interphase between solid electrolytes and lithium metal using neutrons

Andrew S. Westover, Katie L. Browning, Antonino Cannavo et al. (+6 more)

Interfaces are the key to next generation high energy batteries including solid state Li metal batteries. In solid state batteries, the buried nature of solid solid electrolyte electrode interfaces makes studying them difficult. Neutrons have significant potential to non destructively probe these buried solid solid interfaces. This work presents a comparative study using both neutron depth profiling (NDP) and neutron reflectometry (NR) to study a model lithium metal-lithium phosphorus oxynitride (LiPON) solid electrolyte system. In the NDP data, no distinct interphase is observed at the interface. NR shows a difference between electrodeposited, and vapor deposited LiPON -Li interfaces but finds both are gradient interphases that are less than 30 nm thick. Additional simulations of the LiPON-Li2O-Li system demonstrate that NDP has an excellent resolution in the 50 nm-1 mm regime while NR has an ideal resolution from 0.1 - 200 nm with different sample requirements. Together NDP and NR can provide a complementary understanding of interfaces between Li metal and solid electrolytes across relevant length scales.
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All authors Andrew S. Westover, Katie L. Browning, Antonino Cannavo, Ralph Gilles, Jiri Vacik, James F. Browning, Neelima Paul, Giovanni Ceccio, Vasyl Lavrentiev

Mesoscale and Nanoscale Physics · Cross-listed from quant-ph

Mitigating the Transition of SiV$^-$ in Diamond to an Optically Dark State

Manuel Rieger, Rubek Poudel, Tobias Waldmann et al. (+7 more)

Negatively charged silicon vacancy centers in diamond (SiV$^-$) are promising for quantum photonic technologies. However, when subject to resonant optical excitation, they can inadvertently transfer into a zero-spin optically dark state. We show that this unwanted change of charge state can be quickly reversed by the resonant laser itself in combination with static electric fields. By defining interdigitated metallic contacts on the diamond surface, we increase the steady-state SiV$^-$ photoluminescence under resonant excitation by a factor $\ge3$ for most emitters, making it practically constant for certain individual emitters. We electrically activate single \sivs near the positively biased electrode, which are entirely dark without applying local electric fields. Using time-resolved 3-color experiments, we show that the resonant laser not only excites the SiV$^-$, but also creates free holes that convert SiV$^{2-}$ to SiV$^-$ on a timescale of milliseconds. Through analysis of several individual emitters, our results show that the degree of electrical charge state controllability differs between individual emitters, indicating that their local environment plays a key role. Our proposed electric-field-based stabilization scheme enhances deterministic charge state control in group-IV color centers and improves its understanding, offering a scalable path toward quantum applications such as entanglement generation and quantum key distribution.
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All authors Manuel Rieger, Rubek Poudel, Tobias Waldmann, Lina M. Todenhagen, Stefan Kresta, Nori N. Chavira Leal, Viviana Villafañe, Martin S. Brandt, Kai Müller, Jonathan J. Finley

Mesoscale and Nanoscale Physics

Multipolar orbital relaxation of the $t_{2g}$ states

Aurélien Manchon, Xiaobai Ning, Chi Sun et al. (+3 more)

Using a nonperturbative approach, the relaxation rate of orbital dipolar and quadrupolar moments is computed analytically for the t2g states. In the presence of short-range impurities and in the absence of spin-orbit coupling, the orbital relaxation emerges from the competition between momentum scattering and the effect of the crystal field. In the case of weak disorder, the orbital relaxation time is proportional to the momentum scattering time: each scattering event contributes to destroying the orbital moment. In the case of strong disorder, the effect of the crystal field is averaged out, and the orbital relaxation time is inversely proportional to the momentum scattering. We finally find that the dipolar and quadrupolar orbital moments are coupled by the crystal field, resulting in a complex dynamical behavior upon orbital injection.
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All authors Aurélien Manchon, Xiaobai Ning, Chi Sun, Tetsuya Sato, Takeo Kato, Tatiana Rappoport

Mesoscale and Nanoscale Physics

Quantum Spin Hall Effect and Su-Schrieffer-Heeger Model Implementation in Novel C3N-based Dumbbell Morphologies

Deep Mondal, Arka Bandyopadhyay, Atanu Nandy et al. (+1 more)

Two-dimensional carbon nitride materials have been the center of attention for their diverse usage in energy harvesting, environmental remediation and nanoelectronic applications. A broad range of utilities with decent synthetic plausibility have made this family a sweet spot to dive into, whereas the underlying analytical aspects are yet to have prominence. Recently, using the machinaries of first principles, we reported a family of six different structures C3NX with a unique dumbbell-shaped morphology, functionalizing the recently synthesized monolayer of C3N. Here we have critically explored the non-trivial topological phases of the semimetallic Dumbbell C3NX sheets and nanoribbons. Spin-orbit coupling induced gap across the Fermi level, its subsequent tuning via an external electric field, portrayal of band inversion from the Berry curvature distribution and the evaluation of topological index using the Wannier charge center (WCC) firmly establishes the traces of topological footprint. The real space decimation scheme and Green function technique evaluate the underlying spectral information with corresponding transport characteristics. Fascinating features of these quasi-1D systems are observed utilizing the Su-Schrieffer-Heeger (SSH) model where different twisted phases reveal distinct topological signatures even in a low atomic mass system like DB C4N.
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All authors Deep Mondal, Arka Bandyopadhyay, Atanu Nandy, Debnarayan Jana

Mesoscale and Nanoscale Physics

Effect of Spin-Orbit Coupling on Anomalous Quantum Oscillations in InAs/GaSb Quantum Wells

Xinlong Du, Chao Wang, Bo Ying et al. (+1 more)

We theoretically study the effect of spin-orbit coupling (SOC) on anomalous quantum oscillations in InAs/GaSb quantum wells. By comparing different cases, we show that SOC induces two opposing effects on anomalous quantum oscillations: it suppresses the oscillations in the clean case, while enhancing them in the disordered case. Using an effective model, we analyze in detail the origins of anomalous oscillations in both clean and disordered cases. Based on these origins, we explain why SOC suppresses or enhances the anomalous oscillations in different cases, thereby extending the understanding of the conventional theory. Moreover, in the disordered case, SOC can induce a phase shift of the anomalous oscillations. We further identify a parameter window where the anomalous oscillations are significantly enhanced in the presence of both disorder and SOC. These results provide a theoretical basis for understanding the role of SOC in anomalous quantum oscillations.
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All authors Xinlong Du, Chao Wang, Bo Ying, Juntao Song

Strongly Correlated Electrons

Kitaev Meets Affleck-Kennedy-Lieb-Tasaki: Competing Quantum Disorder in Spin-3/2 Honeycomb Systems

Sogen Ikegami, Kiyu Fukui, Rico Pohle et al. (+1 more)

We investigate an S=3/2 quantum spin model on a two-dimensional honeycomb lattice that continuously interpolates between two paradigmatic quantum disordered states with distinct entanglement structures: the Kitaev quantum spin liquid and the Affleck-Kennedy-Lieb-Tasaki (AKLT) valence bond solid. Combining classical, semi-classical, and exact diagonalization approaches, we map out the ground-state phase diagram and elucidate the role of quantum fluctuations across the entire parameter range. While classical and semi-classical frameworks predict noncoplanar orders competing with a collinear Néel state, we find these phases to be fragile: once full quantum fluctuations are included, they melt into a quantum-entangled state characterized by suppressed spin correlations and enhanced entanglement entropy. Our findings highlight how competition between qualitatively different quantum disordered phases provides a fertile playground for unconventional phases emerging from their interplay and quantum fluctuations.
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All authors Sogen Ikegami, Kiyu Fukui, Rico Pohle, Yukitoshi Motome

Materials Science

Rewritable Complementary Nanoelectronics Enabled by Electron-Beam Programmable Ambipolar Doping

Qing Lan, Wenqing Song, Siyin Zhu et al. (+13 more)

The ability to reversibly and site-selectively tune ambipolar doping in a single semiconductor is crucial for reconfigurable electronics beyond silicon, but remains highly challenging. Here, we present a rewritable architecture based on electron-beam programmable field-effect transistors (FETs). Using WSe$_2$ as a model system, we demonstrate electron-beam-induced doping that enables reversible, precisely controlled carrier modulation exceeding $10^{13}$ cm$^{-2}$. The in-situ writing, erasing, and rewriting of ambipolar doping of nanoscale patterns was directly visualized by scanning microwave impedance microscopy. This mask-free, lithography-compatible approach can achieve precise band engineering within individual channels, yielding near-ideal subthreshold swings (~ 60 mV/dec) and finely tunable threshold voltages for both carrier types without specialized contact engineering. These capabilities allow on-demand realization of high performance logic, including CMOS inverters with high voltage gains and low power consumption, as well as NAND-to-NOR transitions on the same device via direct polarity rewriting. Our platform offers a scalable and versatile route for rapid prototyping of complementary electronics.
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All authors Qing Lan, Wenqing Song, Siyin Zhu, Yi Zhou, Lu Wang, Junjie Wei, Jiaqi Liu, Zejing Guo, Takashi Taniguchi, Kenji Watanabe, Hai Huang, Jingli Wang, Xiaodong Zhou, Alex Zettl, Jian Shen, Wu Shi

Mesoscale and Nanoscale Physics

Acoustoelectric Probing of Fractal Energy Spectra in Graphene/hBN Moiré Superlattices

Wenqing Song, Yicheng Mou, Qing Lan et al. (+6 more)

Moiré superlattices with long-range periodicity exhibit Hofstadter energy spectra under accessible magnetic fields, enabling the exploration of emergent quantum phenomena through a hierarchy of fractal states. However, higher-order features, located at elevated energies with narrow bandwidths, typically require high carrier densities and remain difficult to resolve using conventional electrical transport due to limited sensitivity and strong background conductivity. Here, we utilize acoustoelectric (AE) transport to probe high-order fractal states and the Hofstadter spectrum in graphene/hBN moiré superlattices. Surface acoustic waves on a ferroelectric LiNbO$_3$ substrate generate an AE voltage proportional to the derivative of electrical conductivity, significantly enhancing sensitivity to weak spectral features. Combined with substrate-induced high electron doping, this technique resolves fractal Brown-Zak oscillations up to the fifth-order and provides the first AE observation of the Hofstadter butterfly, revealing high-order fractal magnetic Bloch states and symmetry-broken Landau levels over a wide carrier density range. Our results establish AE transport as a powerful derivative-sensitive probe for emergent fractal quantum states in moiré-engineered 2D systems.
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All authors Wenqing Song, Yicheng Mou, Qing Lan, Guorui Zhao, Zejing Guo, Jiaqi Liu, Tuoyu Zhao, Cheng Zhang, Wu Shi

Materials Science

Resistance of refractory high-entropy alloys to ultrafast laser irradiation

Nikita Medvedev

Response of refractory high-entropy alloys MoNbTaVW and HfNbTaTiZr to ultrafast laser radiation is modelled with the hybrid code XTANT-3, combining tight-binding molecular dynamics with the transport Monte Carlo and Boltzmann equation. A two-temperature state with elevated electronic temperature and a cold atomic lattice is studied. The parameters of the electronic system in such a state are evaluated: electronic heat capacity, thermal conductivity, and electron-phonon coupling parameter with the electronic temperatures up to ~25,000 K. It is also demonstrated that the two refractory alloys do not show signs of nonthermal melting up to the deposited doses of ~10 eV/atom, making them more radiation resistant than the Cantor alloy or stainless steel. These results suggest that heavy-element high-entropy alloys are more radiation resistant than those containing only lighter elements. Damage in irradiated HfNbTaTiZr starts with the selective diffusion of Ti atoms, forming a transient superionic-like state.
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Materials Science

Scale-robust Low Resistance Transport in Atomic Layer Deposited Topological Semimetal Wafers on Amorphous Substrate

Dong-Hyun Lim, Young-Min Song, Yeji Kim et al. (+8 more)

As data-centric computing advances, energy-efficient interconnects are increasingly critical for AI-driven systems. Traditional metal conductors face severe limitations at nanoscale due to increased resistivity from surface scattering. In response, this study demonstrates the first wafer-scale realization of an amorphous topological semimetal, tantalum phosphide (TaP), grown directly on amorphous SiO2 substrates (without any seed layers) using low-temperature atomic layer deposition (ALD). The resulting TaP films exhibit unconventional resistivity scaling: decreasing resistivity with decreasing thickness, reaching 227 micro-ohm cm at ~2.3 nm film thickness. This behavior, observed without crystalline order or seed layers, indicates dominant surface conduction and establishes ALD-TaP as a promising candidate for back-end-of-line integration. The films also show excellent conformality, stoichiometry control, and thermal stability up to 600 degree C. A two-channel conduction model confirms surface-dominated transport in ultrathin regimes, further supported by enhanced conductivity in multi-stacked configurations. These findings highlight the potential of amorphous topological semimetals for future high-density, low-power electronic interconnects and expand the applicability of ALD for integrating novel quantum materials at scale.
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All authors Dong-Hyun Lim, Young-Min Song, Yeji Kim, Ae Rim Choi, Hyun-Mi Kim, Hyeongkeun Kim, Sujin Kwon, Bonggeun Shong, Justin Shih, Asir Intisar Khan, Il-Kwon Oh

Disordered Systems and Neural Networks · Cross-listed from cs.LG

Entropic Confinement and Mode Connectivity in Overparameterized Neural Networks

Luca Di Carlo, Chase Goddard and David J. Schwab

Modern neural networks exhibit a striking property: basins of attraction in the loss landscape are often connected by low-loss paths, yet optimization dynamics generally remain confined to a single convex basin and rarely explore intermediate points. We resolve this paradox by identifying entropic barriers arising from the interplay between curvature variations along these paths and noise in optimization dynamics. Empirically, we find that curvature systematically rises away from minima, producing effective forces that bias noisy dynamics back toward the endpoints - even when the loss remains nearly flat. These barriers persist longer than energetic barriers, shaping the late-time localization of solutions in parameter space. Our results highlight the role of curvature-induced entropic forces in governing both connectivity and confinement in deep learning landscapes.
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Quantum Gases

Trion ordering in the attractive three-color Hubbard model on a $\pi$-flux square lattice

Xiang Li, Yumeng Li, Quan Fu et al. (+1 more)

Ultracold multicomponent fermions (atoms/molecules) loaded in optical lattices provide an ideal platform for simulating SU($N$) Hubbard models that host unconventional many-body quantum states beyond SU(2). A prime example is the attractive three-color Hubbard model, in which trion states emerge at strong coupling. Nevertheless, much of its trion ordering on two-dimensional lattices remains uncertain. Here, we employ the determinant quantum Monte Carlo (DQMC) method to simulate the attractive three-color Hubbard model on a $\pi$-flux square lattice at half filling. We show that color-dependent attractive interaction can induce coexisting charge density wave (CDW) and Néel ordered states in the three-color $\pi$-flux Hubbard model. In particular, enhanced charge fluctuations (cf. honeycomb lattice) cause much stronger Néel ordering on the $\pi$-flux square lattice. The coexisting charge and Néel orders survive up to a melting temperature, at which they vanish simultaneously. The Ginzburg-Landau (GL) analysis on the coexistence of CDW and Néel orders demonstrates how color-dependent Hubbard interactions stabilize coexisting orders from the perspective of GL free energy principle.
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All authors Xiang Li, Yumeng Li, Quan Fu, Yu Wang

Mesoscale and Nanoscale Physics

Robust AC vector sensing at zero magnetic field with pentacene

Boning Li, Garrett Heller, Jungbae Yoon et al. (+6 more)

Quantum sensors based on electronic spins have emerged as powerful probes of microwave-frequency fields. Among other solid-state platforms, spins in molecular crystals offer a range of advantages, from high spin density to functionalization via chemical tunability. Here, we demonstrate microwave vector magnetometry using the photoexcited spin triplet of deuterated pentacene molecules, operating at zero external magnetic field and room temperature. We achieve full three-dimensional microwave field reconstruction by detecting the Rabi frequencies of anisotropic spin-triplet transitions associated with two crystallographic orientations of pentacene in naphthalene crystals. We further introduce a phase alternated protocol that extends the rotating-frame coherence time by an order of magnitude and enables sensitivities of $1~\mu\mathrm{T}/\sqrt{\mathrm{Hz}}$ with sub-micrometer spatial resolution. These results establish pentacene-based molecular spins as a practical and high-performance platform for microwave quantum sensing, and the control techniques are broadly applicable to other molecular and solid-state spin systems.
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All authors Boning Li, Garrett Heller, Jungbae Yoon, Alexander Ungar, Hao Tang, Guoqing Wang, Patrick Hautle, Yifan Quan, Paola Cappellaro

Mesoscale and Nanoscale Physics

Angle evolution of the superconducting phase diagram in twisted bilayer WSe2

Yinjie Guo, John Cenker, Ammon Fischer et al. (+13 more)

Recent observations of superconductivity in twisted bilayer WSe$_2$ have extended the family of moiré superconductors beyond twisted graphene. In WSe$_2$ two different twist angles were studied, 3.65{\deg} and 5.0{\deg}, and two seemingly distinct superconducting phase diagrams were reported, raising the question of whether the superconducting phases in the two devices share a similar origin. Here we address the question by experimentally mapping the evolution of the phase diagram across devices with twist angles spanning the range defined by the initial reports, and comparing the results to twist angle-dependent theory. We find that the superconducting state evolves smoothly with twist angle and at all twist angles is proximal to a Fermi surface reconstruction with, presumably, antiferromagnetic ordering, but is neither necessarily tied to the Van Hove singularity, nor to the half band insulator. Our results connect the previously distinct phase diagrams at 3.65{\deg} and 5{\deg}, and offer new insight into the origin of the superconductivity in this system and its evolution as the correlation strength increases. More broadly, the smooth phase diagram evolution, repeatability between different devices, and dynamic gate tunability within each device, establish twisted transition metal dichalcogenides as a unique platform for the study of correlated phases as the ratio of interaction strength to bandwidth is varied.
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All authors Yinjie Guo, John Cenker, Ammon Fischer, Daniel Muñoz-Segovia, Jordan Pack, Luke Holtzman, Lennart Klebl, Kenji Watanabe, Takashi Taniguchi, Katayun Barmak, James Hone, Angel Rubio, Dante M. Kennes, Andrew J. Millis, Abhay Pasupathy, Cory R. Dean

Strongly Correlated Electrons

Competing magnetic phases in Cr$_{3+\delta}$Te$_4$ are spatially segregated

V. K. Bhartiya, Anirban Goswami, Nicholas Ng et al. (+10 more)

Cr$_{1+x}$Te$_2$ is a self-intercalated vdW system that is of current interest for its room-temperature FM phases and tunable topological properties. Early NPD measurements on the monoclinic phase Cr$_3$Te$_4$ ($x=0.5$) presented evidence for competing FM and AFM phases. Here we apply neutron diffraction to a single crystal of Cr$_{3+\delta}$Te$_4$ with $\delta=-0.10$ and discover that it consists of two distinct monoclinic phases, one with FM order below $T_{\rm C} \approx 321$ K and another that develops AFM order below $T_{\rm N} \approx 86$ K. In contrast, we find that a crystal with $\delta=-0.26$ exhibits only FM order. The single-crystal analysis is complemented by results obtained with NPD, XPD, and TEM measurements on the $\delta=-0.10$ composition. From observations of spontaneous magnetostriction of opposite sign at $T_{\rm C}$ and $T_{\rm N}$, along with the TEM evidence for both monoclinic phases in a single thin ($\approx$ 100 nm) grain, we conclude that the two phases must have a fine-grained ($\lesssim$ 100 nm) intergrowth character, as might occur from high-temperature spinodal decomposition during the growth process. Calculations of the relaxed lattice structures for the FM and AFM phases with DFT provide a rationalization of the observed spontaneous magnetostrictions. Correlations between the magnitude and orientation of the magnetic moments with lattice parameter variation demonstrate that the magnetic orders are sensitive to strain, thus explaining why magnetic ordering temperatures and anisotropies can be different between bulk and thin-film samples, when the latter are subject to epitaxial strain. Our results point to the need to investigate the supposed coexistence FM and AFM phases reported elsewhere in the Cr$_{1+x}$Te$_2$ system, such as in the Cr$_5$Te$_8$ phase ($x=0.25$).
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All authors V. K. Bhartiya, Anirban Goswami, Nicholas Ng, Wei Tian, Matthew G. Tucker, Niraj Aryal, Lijun Wu, Weiguo Yin, Yimei Zhu, Milinda Abeykoon, Emmanuel Yakubu, Samaresh Guchhait, J. M. Tranquada

Statistical Mechanics · Cross-listed from hep-th

Maximally Symmetric Boost-Invariant Solutions of the Boltzmann Equation in Foliated Geometries

Mauricio Martinez and Christopher Plumberg

In this work we study the relativistic kinetic theory of a boost-invariant conformal gas on a static, maximally symmetric background $dS_3\times \mathbb{R}$, considering all constant-curvature slicings of $dS_3$ - flat, spherical, or hyperbolic- and their associated symmetry groups. Using a symmetry-driven cotangent-bundle approach, we show that the isometry group of each slicing acts on phase space in such a way that only its Casimir invariants and the time-like coordinate unconstrained, so the distribution function depends solely on these quantities. This yields a unified boost-invariant exact solution of the Boltzmann equation valid for each constant-curvature foliation of $dS_3\times \mathbb{R}$. Specializing this general solution to the flat and spherical foliations reproduces the Bjorken and Gubser flows, respectively, while its restriction to the hyperbolic foliation produces a genuinely new analytic solution (`Grozdanov flow'). Hydrodynamics and free streaming emerge naturally as limiting regimes of this novel exact solution. We further comment on several relevant aspects of the new boost-invariant solution on the hyperbolic slicing and on their interpretation once mapped back to Minkowski space.
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Mesoscale and Nanoscale Physics

Enhanced polariton interaction in the presence of disorder

Matthew Prest, Cassandra Imperato, Oleg L. Berman et al. (+2 more)

We consider the interaction between exciton-polaritons in a semiconductor quantum well, embedded in a microcavity, in the presence of disorder. The disorder acts on the excitons in the semiconductor quantum well. We have calculated the exciton and polariton self-energies and the exciton and polariton energy dispersion relations in the presence of disorder. Our results demonstrate that disorder increases the polariton-polariton interaction.
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All authors Matthew Prest, Cassandra Imperato, Oleg L. Berman, David W. Snoke, Klaus Ziegler

Strongly Correlated Electrons

Ultrasonic observation of small Fermi surfaces in La$T$In$_5$ ($T$ = Co, Rh, Ir)

Ryosuke Kurihara, Yusuke Hirose, Kazuki Matsui et al. (+8 more)

We performed high-field ultrasonic measurements on La$T$In$_5$ ($T$ = Co, Rh, Ir) to reveal the origin of the small Fermi surface that was recently observed in LaRhIn$_5$ with an oscillation frequency of 6.8 T. We observed quantum oscillations originating from this Fermi surface in LaRhIn$_5$. In addition, we revealed that LaCoIn$_5$ and LaIrIn$_5$ exhibit quantum osciilations with frequencies below 100 T, indicating hidden Fermi surfaces in these compounds. Furthermore, Co-substituted LaRhIn$_5$ exhibited quantum oscillations with a frequency of 10 T. Our results suggest that the small Fermi surface originates from bulk properties and that $3d$ electrons of the transition metal contribute to its formation.
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All authors Ryosuke Kurihara, Yusuke Hirose, Kazuki Matsui, Atsushi Miyake, Ryoma Tsunoda, Masaki Kondo, Rikio Settai, Mitsuhiro Akatsu, Yuichi Nemoto, Hiroshi Yaguchi, Masashi Tokunaga

Soft Condensed Matter

Protocol to evaluate the viscoelastic response of a polymer suspension to an active agent via oscillatory shear rheometry

Kai Qi, Qingzhi Zou and Ignacio Pagonabarraga

Microorganisms inhabit viscoelastic environments, where their locomotion can deform polymers and trigger local complex viscoelastic responses. However, a systematic approach to quantify such responses remains lacking. Here, we propose a protocol that maps the shear effect induced by an active agent to oscillatory shear rheometry. The central idea is to establish a correspondence between the mean shear rate generated by swimming and that produced by an oscillating plate. In this mapping, the swimming velocity and active stress are translated into an effective oscillation frequency and strain amplitude. The resulting viscoelastic response can then be evaluated by standard oscillatory rheometry. The protocol is validated using lattice Boltzmann simulations of a squirmer embedded in polymer solutions. Our framework is generic and can be naturally extended to active microrheology, providing a pathway to quantify swimmer-induced viscoelasticity.
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Friday 5 December

Materials Science · Cross-listed from cs.DL

Expert-Grounded Automatic Prompt Engineering for Extracting Lattice Constants of High-Entropy Alloys from Scientific Publications using Large Language Models

Shunshun Liu, Talon R. Booth, Yangfeng Ji et al. (+2 more)

Large language models (LLMs) have shown promise for scientific data extraction from publications, but rely on manual prompt refinement. We present an expert-grounded automatic prompt optimization framework that enhances LLM entity extraction reliability. Using high-entropy alloy lattice constant extraction as a testbed, we optimized prompts for Claude 3.5 Sonnet through feedback cycles on seven expert-annotated publications. Despite a modest optimization budget, recall improved from 0.27 to > 0.9, demonstrating that a small, expert-curated dataset can yield significant improvements. The approach was applied to extract lattice constants from 2,267 publications, yielding data for 1,861 compositions. The optimized prompt transferred effectively to newer models: Claude 4.5 Sonnet, GPT-5, and Gemini 2.5 Flash. Analysis revealed three categories of LLM mistakes: contextual hallucination, semantic misinterpretation, and unit conversion errors, emphasizing the need for validation protocols. These results establish feedback-guided prompt optimization as a low-cost, transferable methodology for reliable scientific data extraction, providing a scalable pathway for complex LLM-assisted research tasks.
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All authors Shunshun Liu, Talon R. Booth, Yangfeng Ji, Wesley Reinhart, Prasanna V. Balachandran

Soft Condensed Matter

Unlocking the full potential of jumping condensation on microstructured surfaces

Mariia S. Kiseleva, Tytti Karki, Mika Latikka et al. (+11 more)

Water condensation on superhydrophobic surfaces can generate spontaneous droplet jumping, enabling rapid condensate removal and improved thermal and mass transfer. Although this effect has been extensively demonstrated on densely packed nanostructures, the capability of microscale textures to support jumping condensation remains poorly understood. Here, we show that engineered microscale conical arrays can achieve efficient microdroplet jumping and reveal a previously unreported spacing-dependent critical transition between jumping and non-jumping regimes. In the jumping regime, by varying only the cone pitch, we identify a geometric threshold below which sub-10 micron droplets are rapidly removed, and above which jumping is suppressed, resulting in slower dynamics and larger departing droplets. In situ optical and environmental scanning electron microscopies reveal the mechanistic origin of this transition: dense arrays favour full Cassie droplets, which depart cleanly, while wider spacing favours partial Cassie droplets that retain a localized wet region initiating new nucleation. From these results, we construct a geometry-wetting design map linking microstructure spacing, droplet morphology, and nucleation density. These findings establish design principles for scalable, mechanically robust microstructured surfaces capable of high-performance condensation management for anti-fogging, water harvesting, and heat-transfer applications.
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All authors Mariia S. Kiseleva, Tytti Karki, Mika Latikka, Parham Koochak, Sakari Lepikko, Maja Vuckovac, Tomi Koskinen, Ramesh Raju, Ville P. Jokinen, Jiazheng Liu, Nenad Miljkovic, Jaakko V.I. Timonen, Ilkka Tittonen, Robin H. A. Ras

Statistical Mechanics · Cross-listed from cs.LG

Generative Stochastic Optimal Transport: Guided Harmonic Path-Integral Diffusion

Michael Chertkov

We introduce Guided Harmonic Path-Integral Diffusion (GH-PID), a linearly-solvable framework for guided Stochastic Optimal Transport (SOT) with a hard terminal distribution and soft, application-driven path costs. A low-dimensional guidance protocol shapes the trajectory ensemble while preserving analytic structure: the forward and backward Kolmogorov equations remain linear, the optimal score admits an explicit Green-function ratio, and Gaussian-Mixture Model (GMM) terminal laws yield closed-form expressions. This enables stable sampling and differentiable protocol learning under exact terminal matching. We develop guidance-centric diagnostics – path cost, centerline adherence, variance flow, and drift effort – that make GH-PID an interpretable variational ansatz for empirical SOT. Three navigation scenarios illustrated in 2D: (i) Case A: hand-crafted protocols revealing how geometry and stiffness shape lag, curvature effects, and mode evolution; (ii) Case B: single-task protocol learning, where a PWC centerline is optimized to minimize integrated cost; (iii) Case C: multi-expert fusion, in which a commander reconciles competing expert/teacher trajectories and terminal beliefs through an exact product-of-experts law and learns a consensus protocol. Across all settings, GH-PID generates geometry-aware, trust-aware trajectories that satisfy the prescribed terminal distribution while systematically reducing integrated cost.
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Statistical Mechanics · Cross-listed from cs.LG

Adaptive Path Integral Diffusion: AdaPID

Michael Chertkov and Hamidreza Behjoo

Diffusion-based samplers – Score Based Diffusions, Bridge Diffusions and Path Integral Diffusions – match a target at terminal time, but the real leverage comes from choosing the schedule that governs the intermediate-time dynamics. We develop a path-wise schedule – selection gramework for Harmonic PID with a time-varying stiffness, exploiting Piece-Wise-Constant(PWC) parametrizations and a simple hierarchical refinement. We introduce schedule-sensitive Quality-of-Sampling (QoS) diagnostics. Assuming a Gaussian-Mixture (GM) target, we retain closed-form Green functions' ration and numerically stable, Neural-Network free oracles for predicted-state maps and score. Experiments in 2D show that QoS driven PWC schedules consistently improve early-exit fidelity, tail accuracy, conditioning of the dynamics, and speciation (label-selection) timing at fixed integration budgets.
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Quantum Gases

Evaporative damping in open system theory of Bose-Einstein Condensates

Nils A. Krause and Ashton S. Bradley

We derive a new damping mechanism in the open quantum systems description of Bose-Einstein condensates. It stems from previously neglected terms in the derivation of the stochastic projective Gross-Pitaevskii equation (SPGPE), accounting for a nonlinear evaporation of particles from the coherent into the incoherent region. We demonstrate that the mechanism, while so far assumed to be of minor importance, is comparable in strength to the widely employed number damping. We also provide a simplified (pseudo)-local and a dimensionally reduced form of this evaporative damping. The process completes the SPGPE description of ultracold Bose gases giving a full first-principles picture of their evolution at finite temperature.
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Mesoscale and Nanoscale Physics

Modeling and Optimization of Two-Terminal Spin-Orbit-Torque MRAM

Md Nahid Haque Shazon, Piyush Kumar, Luqiao Liu et al. (+2 more)

This paper presents physical modeling and benchmarking for two-terminal spin-orbit torque magnetic random-access memory (2T-SOT-MRAM). The results indicate that the common SOT materials that provide only in-plane torque can provide little to no improvement over spin-transfer-torque (STT) MRAM in terms of write energy. However, emerging SOT materials that provide out-of-plane torques with efficiencies as small as 0.1 can result in significant improvements in the write energy for such 2-terminal devices, especially when the magnet lateral dimensions are scaled down to 30 or 20 nm. Additionally, a novel 2T-SOT MRAM device is proposed that can increase the path electrons pass through the SOT layer; hence, increasing the generated spin current and the energy efficiency of the device. Our benchmarking results indicate that an out-of-plane SOT efficiency of 0.051 for 20nm wide devices can result in write energies approaching SRAM at the 7nm technology node.
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All authors Md Nahid Haque Shazon, Piyush Kumar, Luqiao Liu, Daniel C. Ralph, Azad Naeemi

Materials Science · Cross-listed from nucl-ex

Enhanced nuclear fusion in the sub-keV energy regime

Micah. E. Karahadian, Matthew Colborne, Arun Persaud et al. (+2 more)

Nuclear fusion requires overcoming or traversing a repulsive Coulomb barrier of hundreds of kiloelectronvolts, rendering the probability of fusion at sub-keV energies vanishingly small. Yet in condensed matter, the electronic and structural environment of reacting nuclei can profoundly alter fusion rates. Here we demonstrate that deuterium-deuterium fusion within metallic foils exhibits a pronounced enhancement and reaction yield plateau below energies of 2.5 keV- contrary to the expected exponential suppression with decreasing energy. Using a dual-chamber platform that combines electrochemical deuterium loading with ion-beam bombardment, we show that fusion yields in palladium and titanium hydrides are enhanced by over 10^18 compared to theoretical bare-nucleus fusion rates. These results demonstrate that access to low-energy fusion processes can be governed by materials degrees of freedom. This materials-driven fusion regime establishes a reproducible, tunable framework for studying and ultimately engineering nuclear reactions in solids. While the reaction rates reported here are low, these insights into materials-modulated fusion processes offer a potential foundation for understanding how condensed-matter environments could influence future fusion-energy concepts.
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All authors Micah. E. Karahadian, Matthew Colborne, Arun Persaud, Thomas Schenkel, Jeremy N. Munday

Materials Science

Polarons from first principles

Zhenbang Dai, Jon Lafuente-Bartolome and Feliciano Giustino

This article reviews recent theoretical developments in the ab initio study of polarons in materials. The polaron is an emergent quasiparticle that arises from the interaction between electrons and phonons in solids, and consists of an electron or a hole accompanied by a distortion of the crystal lattice. Recent advances in experiments, theory, and computation have made it possible to investigate these quasiparticles with unprecedented detail, reigniting the interest in this classic problem of condensed matter physics. Recent theoretical and computational advances include ab initio calculations of polaron spectral functions, wavefunctions, lattice distortions, and transport and optical properties. These developments provide new insight into polaron physics, but they have evolved somewhat independently from the earlier effective Hamiltonian approaches that laid the foundation of the field. This article aims to bridge these complementary perspectives by placing them within a single unified conceptual framework. To this end, we start by reviewing effective Hamiltonians of historical significance in polaron theory, ab initio techniques based on density functional theory, and many-body first-principles approaches to polarons. After this survey, we outline a general field-theoretic framework that bridges between these diverse approaches to polaron physics. For completeness, we also review recent progress in the study of exciton polarons and self-trapped excitons and their relations to polarons. Beyond the methodology, we discuss recent applications to several classes of materials that attracted attention in the context of polaron physics.
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Materials Science

From Mono- to Hexa-Interstitials: Computational Insights into Carbon Defects in Diamond

Nima Ghafari Cherati, Arsalan Hashemi and Ádám Gali

We present a comprehensive first-principles investigation of carbon self-interstitial defects in diamond, ranging from mono- to hexa-interstitial complexes. By quantum mechanical density functional theory, empowered by interatomic potential models, we efficiently sample the complex configurational landscape and identify both known and previously unreported defect geometries. Our results reveal a pronounced energetic driving force for aggregation: the formation energy per interstitial decreases systematically from isolated split interstitials to compact multi-interstitial clusters, with the tetra-interstitial platelet emerging as a particularly stable structural motif. Additionally, charge analysis indicates that the predominantly covalent bonding in diamond becomes more polar within the defect centers. Analysis of defect energy levels shows that only the investigated mono-, di-, penta-, and hexa-interstitial complexes introduce in-gap electronic states, whereas the tri- and tetra-interstitial clusters are electronically inert. Vibrational spectroscopies further reveal that self-interstitials generate characteristic signatures. Short carbon-carbon bonds inside the defect cores give rise to high-frequency vibrational modes between 1375 and 1925 cm$^{-1}$, which are strongly IR-active but exhibit weak Raman activity. Through a systematic analysis of metastable configurations, we identify the 3H defect center as a neutral di-interstitial defect. Based on this identification, we further suggest that the TR12 center may arise from a 3H-containing defect like a metastable hexa-interstitial configuration. Taken together, these findings provide a coherent picture of the structural, electronic, and vibrational characteristics of carbon self-interstitials and establish a robust framework for their experimental identification.
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Superconductivity

A Landau Theory for Pair Density Modulation in Fe(Te,Se) flakes

Po-Jui Chen and Piers Coleman

Motivated by recent scanning tunneling microscopy (STM) experiments reporting a pair-density modulation (PDM) in flakes of FeTe${_{0.55}}$Se${_{0.45}}$, we develop a Landau theory to elucidate its physical origin. We analyze the PDM in terms of screw and glide symmetries, interpreting it as a hybridized state of two order parameters with opposite glide and screw parity. To explain the absence of PDM in the bulk, we argue that the breaking of glide symmetry at the surface allows nematic order to selectively stabilize the PDM in thin flakes. From these symmetry constraints, we show that the opposing glide and screw parities of the condensate favor a site-based, rather than bond-based, pairing mechanism. Thus the discovery of PDM in superconducting flakes suggests that the pairing in iron-based superconductors is local to the iron atoms, possibly driven by Hunds coupling. We argue that the mismatch in Knight shift between the even and odd parity order parameters will lead to a magnetic-field enhancement of the PDM at low fields, and a reentrant triplet phase at high fields that can be tested in STM experiments.
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Other Condensed Matter · Cross-listed from physics.optics

Tunable Narrowband Terahertz Radiation from van der Waals Ferroelectrics

Chun-Ying Huang, Taketo Handa, Daniel G. Chica et al. (+10 more)

The terahertz (THz) spectral range is central to high-speed communication, precision metrology, sensing technologies, and a range of fundamental scientific investigations. Achieving these capabilities in practical systems increasingly demands chip-scale integration of THz photonic components that are typically bulky. In this context, van der Waals (vdW) materials provide a unique platform for integrated nonlinear photonics in the visible and near-infrared regimes, and extending this framework into the THz domain would constitute a significant advance. Here, we report tunable, intense, and narrowband THz radiation from ferroelectric niobium oxyhalides. Through halogen substitution and alloying, we achieve continuous and precise control over the emission frequency from 3.1 to 5.8 THz. We show that the narrowband THz radiation is driven by phonons associated with the ferroelectric polarization. We further demonstrate dynamic and nonvolatile control of the polarity of the coherent THz wave with external electric field. This work demonstrates efficient narrowband THz emission from vdW ferroeletrics and provides microscopic insight into its origin, paving the way for on-chip THz technology for a broad range of applications.
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All authors Chun-Ying Huang, Taketo Handa, Daniel G. Chica, Zhihao Cui, Ding Xu, Jeongheon Choe, Yiliu Li, Margalit L. Feuer, Milan E. Delor, Michael Fechner, David R. Reichman, Xavier Roy, Xiaoyang Zhu