Soft Condensed Matter
Accelerating charging dynamics of electric double-layer capacitors
Megh Dutta, Ivan Palaia, Emmanuel Trizac et al. (+1 more)
Electric double-layer capacitors (EDLCs), consisting of an ionic fluid between two metallic electrodes, are electrochemical energy storage devices complementary to batteries, allowing for a faster charge/discharge. The charging dynamics in response to a voltage step features a variety of regimes and relaxation timescales, depending on the applied voltage and the various lengths characterizing the system, most importantly the inter-electrode distance and the Debye length over which electrostatic effects are screened in the electrolyte. Inspired by recent works on "shortcut to adiabaticity" in colloidal systems, here we investigate the possibility to control the charge and discharge of planar EDLCs using time-dependent voltages. Specifically, our aim is to achieve a full charge or discharge within a finite time shorter than their intrinsic relaxation timescales. Within the Poisson-Nernst-Planck model and the small-voltage regime, we derive time-dependent protocols that can eliminate an arbitrary number of relaxation modes. This permits to approach the
equilibrium charged state within a finite time, that can be in practice an order of magnitude faster than the natural equilibration time. We illustrate the relevance and efficacy of the method on
polynomial drivings and show that the surface charge density, charge-density profiles, and global deviation from
equilibrium (quantified by a Kullback-Leibler-like divergence) can all be significantly accelerated, even for driving times comparable to or shorter than the natural RC time of the system.
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All authors Megh Dutta, Ivan Palaia, Emmanuel Trizac, Benjamin Rotenberg
Strongly Correlated Electrons
Frustration from Localized Zhang-Rice States: A Unified Theory of Doping-Driven Magnetic Transitions in Cuprates
Xiaodong Wang, Ping Xu, Jiong Mei et al. (+5 more)
The microscopic mechanism by which doped holes disrupt the
antiferromagnetic (AFM) order is one of the fundamental questions in cuprates. In this work, we propose a unified microscopic theory in which doped holes form spatially localized Zhang-Rice singlets which actively mediate emergent
spin exchange. Rather than acting as simple non-
magnetic vacancies, these localized states introduce emergent next-nearest $J_2$ and third-nearest $J_3$ neighbor superexchanges. This dopant-induced exchange pathway generates significant
magnetic frustration, naturally explaining the rapid collapse of the Néel AFM order and the emergence of a
spin-glass phase on the hole-doped side. In contrast, electron doping primarily leads to
spin dilution, allowing AFM order to persist to substantially higher doping levels, consistent with the experimentally observed electron-hole asymmetry. Our findings provide a unified microscopic framework for understanding doping-driven
magnetic transitions in lightly doped cuprates.
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All authors Xiaodong Wang, Ping Xu, Jiong Mei, Shao-Hang Shi, Zi-Xiang Li, Mingpu Qin, Kun Jiang, Hui-Ke Jin
Superconductivity
Direction-selective triplet pairing and spin-edge locking in altermagnetic metals
Lie Yuan, Junkang Huang, Yu-Xuan Li et al. (+1 more)
We investigate self-consistent unconventional superconductivity in a two-dimensional $d$-wave altermagnetic metal. We find that momentum-dependent altermagnetic
spin splitting suppresses opposite-
spin singlet pairing and stabilizes highly anisotropic equal-
spin triplet order. In the
spin-conserving limit, this directional triplet pairing gives rise to nearly dispersionless Majorana boundary states associated with effective one-dimensional topological channels. Rashba
spin-orbit coupling mixes
spin sectors, activates additional pairing components, and drives the system into a mixed-parity superconducting state with dispersive Majorana boundary states. The
spin-resolved boundary spectra further reveal a characteristic locking between boundary orientation and
spin polarization, reflecting the underlying altermagnetic
symmetry. These results identify altermagnetic
spin splitting as an intrinsic mechanism for selecting unconventional pairing and generating
spin-resolved Majorana boundary states without external
magnetic fields.
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All authors Lie Yuan, Junkang Huang, Yu-Xuan Li, Tao Zhou
Materials Science
Epitaxial growth and magnetic phase transitions in non-centrosymmetric EuPdSi$_3$ thin films
Sebastian Kölsch, Alfons G. Schuck, Olena Fedchenko et al. (+9 more)
Non-centrosymmetric
magnetic materials are a promising platform for stabilizing
chiral spin textures, such as skyrmions and cycloidal
magnetic states. This is particularly true in epitaxial thin film geometries, where strain and interface effects offer additional control. Herein, we report on the first epitaxial thin films of EuPdSi$_3$ grown by molecular beam epitaxy on MgO(001). X-ray diffraction confirms an epitaxial relationship of tetragonal EuPdSi$_3$ in the BaNiSn$_3$ structure with out-of-plane c-axis orientation and parallel in-plane a-axes. Hard x-ray photoelectron spectroscopy reveals a stable Eu valence of 2.0, yielding a large
magnetic moment of approximately 7 $\mu_B$ per Eu atom in accordance with Hund's rule. Owing to the non-centrosymmetric
crystal structure, non-collinear
magnetic states such as Néel-type skyrmions and cycloidal phases are allowed by
symmetry. Electronic transport measurements reveal two
magnetic phase transitions at 19 K and 15 K in zero applied field. Under
magnetic fields applied along the crystallographic [100] and [001] directions, distinct temperature dependent
magnetic phases emerge, demonstrating the sensitivity of the
magnetic ground state to field orientation in epitaxial EuPdSi$_3$ thin films.
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All authors Sebastian Kölsch, Alfons G. Schuck, Olena Fedchenko, Dmitry Vasilyev, Olena Tkach, Sergeij Chernov, Christoph Schlüter, Andrii Gloskowski, Hans-Joachim Elmers, Gerd Schönhense, Jens Müller, Michael Huth
Mesoscale and Nanoscale Physics
Spin and orbital mixing of edge states in a quantum Hall system proximitized by a superconductor
S. Maji and M. P. Nowak
We investigate the formation and transport properties of
chiral Andreev edge states in a two-dimensional
quantum Hall system proximitized by a
superconductor. By numerically modeling the system using the Bogoliubov-de Gennes equations, we analyze the non-local conductance and transmission probabilities of multimode and spinful systems. We demonstrate that the Andreev reflection process induces a mixing of the
quantum Hall edge modes at higher filling factors, a phenomenon strictly prohibited in clean, purely electronic systems. When incorporating the Zeeman interaction, we show that the Andreev edge states split into uncoupled
spin species, maintaining
spin orthogonality that prevents mixing between opposite
spin sectors. Furthermore, we explore the impact of Rashba
spin-orbit coupling. While the
spin-orbit interaction alone causes slight
spin depolarization, its combination with an in-plane
magnetic field drives complex
spin mixing among all
chiral Andreev bands, fundamentally altering the conductance oscillations. Finally, we reveal that the electron transmission probabilities exhibit robust degeneracies, which emerge as a direct consequence of the unitarity constraints and the particle-hole
symmetry of the system's scattering
matrix in a
magnetic field and the presence of
spin-orbit interaction.
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Mesoscale and Nanoscale Physics
Qumus: Realization of An Embodied AI Quantum Material Experimentalist
Lihan Shi, Zhaoyi Joy Zheng, Xinzhe Juan et al. (+14 more)
While modern Large
Language Models (LLMs) and agentic artificial intelligence (AI) have demonstrated transformative capabilities in digital domains, the realization of
embodied AI capable of real-world scientific discovery remains a difficult frontier. The advancements are hindered by the inherent complexity of integrating high-level
reasoning,
multimodal information processing and real-time physical execution. Here we introduce Qumus, the first AI
quantum materials experimentalist. Physically
embodied within a robotic mini-laboratory, Qumus is an intelligent,
multimodal, and multi-
agent system designed for the creation and nano-processing of atomically thin two-dimensional (2D) materials and stacked van der Waals (vdW) structures. Qumus autonomously navigates the full scientific cycle, from hypothesis generation and protocol planning to multi-step experimental execution, result analysis and reporting, acting as an experimentalist. Markedly, the system has achieved, for the first time, the AI-creation of
graphene, as well as the first AI-fabrication of complex nanodevices including atomically thin field-effect transistors via vdW stacking. Qumus excels at these tasks by demonstrating autonomous error correction and closed-loop experimentation. Our results establish a generalizable framework for self-improving
embodied AI systems that learn directly from the
quantum world, opening a pathway toward accelerated discovery in
quantum materials, electronics and beyond.
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All authors Lihan Shi, Zhaoyi Joy Zheng, Xinzhe Juan, Yimin Wang, Ming Yin, Mayank Sengupta, Kristina Wolinski, Yanyu Jia, Jingzhi Shi, Derek Saucedo, Neill Saggi, Haosen Guan, Kenji Watanabe, Takashi Taniguchi, Ali Yazdani, Mengdi Wang, Sanfeng Wu
Quantum Gases
A study of the dimer-trimer crossover in a driven three-component Fermi gas
Ronnie Slowinski, Gaël Servignat, Frédéric Chevy et al. (+1 more)
We develop an Effective Field Theory (EFT) for a system with three distinguishable atomic species and present a variational calculation of the two and three-body binding energies in
vacuum and in the presence of a single
Fermi sea. Specifically, we consider the case where the interaction between first two atomic species is externally driven so as to produce a (non-universal) closed-channel dimer whose coupling can be controlled independently of all other interactions. We then model the remaining interactions as a contact interaction between the dimer and a third atomic species which forms the medium. We derive analytical expressions for the dimer and trimer binding energies in
vacuum and in medium, and in the latter case we predict a crossing between the dimer and trimer branches as a function of the atom-dimer scattering length, analogous to the usual polaron and molecule problem. Furthermore, we show that the position of this crossing can be controlled by varying the atom-atom coupling that results from the external drive and we discuss the implications of these findings.
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All authors Ronnie Slowinski, Gaël Servignat, Frédéric Chevy, Carlos Lobo
Materials Science
Metastable Cu$_{1-x}$CrTe$_2$ – Completing the copper chromium delafossite series through soft chemistry
Kai D. Röseler, Geo Sciarini, Felix Eder et al. (+3 more)
In the layered copper chromium dichalcogenide series CuCr$X_2$, the
oxide, the sulfide, and the selenide analogues have been reported, but the telluride CuCrTe$_2$ has remained unsynthesized so far. Here, we report the synthesis of Cu$_{1-x}$CrTe$_2$ ($x \approx 0.3$), which forms only within a narrow temperature window near 90 {\deg}C by solvothermal cation exchange of K$_{1-x}$CrTe$_2$ ($x \approx 0.3$) and CuBr. Cu$_{1-x}$CrTe$_2$ undergoes a magnetostructural transition to an
antiferromagnetic state at $T_\mathrm{N}=239$ K, a Néel temperature that is high relative to other $A$CrTe$_2$ phases and comparable to that of
ferromagnetic, fully-deintercalated CrTe$_2$. Cu$_{1-x}$CrTe$_2$ is metastable and decomposes at temperatures as low as 250 {\deg}C to form spinel CuCr$_2$Te$_4$. These results highlight the importance of low-temperature topochemical routes for accessing metastable Cu(I)-containing tellurides that are inaccessible by conventional solid-state synthesis.
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All authors Kai D. Röseler, Geo Sciarini, Felix Eder, Samuel Moody, Vladimir Pomjakushin, Fabian O. von Rohr
Other Condensed Matter · Cross-listed from quant-ph
Topologically protected long-range correlations in steady states of driven-dissipative bosonic chains
Miguel Clavero Rubio, Tomás Ramos and Diego Porras
Driven-dissipative
quantum systems can exhibit robust transport and amplification in topological regimes, yet the connection between
topology and the extent of correlations remains largely unexplored. In this work, we develop a general framework that links topological phases in driven-dissipative systems to bosonic correlations via the singular value decomposition (SVD). In essence, we claim that non-Hermitian
topology in quadratic Liouvillians is directly encoded in steady-state correlations, providing an intrinsic characterization of
topology without external probes. We show that topological amplification induces disorder-robust long-range order (LRO) in steady-state correlations at fixed frequency, establishing frequency-resolved correlations as direct signatures of non-Hermitian topological phases. We introduce a vector-valued topological invariant that captures the total number of singular-value gap closings across the frequency axis, extending the concept of adiabatic deformation from topological
insulators to the case of topological phases of quadratic Liouvillians. Within this framework, we further demonstrate that the spatial structure of equal-time correlations encodes global topological information, manifested as a Gaussian spatial decay with distance in the topological phase, in contrast to the exponential decay characteristic of trivial phases. These findings open new avenues for
quantum sensing and correlation engineering in non-Hermitian systems, with feasible implementations in platforms such as trapped ions and superconducting
circuits.
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Materials Science · Cross-listed from physics.ins-det
A single multi-configuration Direct Electron Detector for various electron imaging and diffraction-based techniques in SEM
Nohayla El-Khairaoui, Julien Guyon, Nathalie Gey et al. (+2 more)
Addressing the need for efficient and integrated multiscale crystallographic and defect analyses of advanced materials, this paper presents the implementation of a new multi-configuration detection system, integrating a single Timepix3-based direct electron detector (DED) in a scanning electron microscope (SEM). By combining precise translation and rotation movements, this system enables, for the first time, the use of the same detector to realize all principal diffraction geometries. These include conventional Electron BackScatter Diffraction (EBSD), off-axis Reflexion Kikuchi Diffraction (RKD), and Transmission Kikuchi Diffraction (TKD) in on-, off- and near-axis configurations. Furthermore, transitions between all these geometries are accomplished without hardware modification. On the other hand, this work presents efficient reconstruction of electron images using the detector data-driven feature, extending thus its applicability to BackScattered Electron imaging (BSE), Electron Channelling Contrast Imaging (ECCI) and Scanning Transmission Electron Imaging in SEM (STEM-in-SEM) characterizations. High-quality Kikuchi patterns easily indexable were acquired across all geometries as well as micrographs of dislocations in both reflection and transmission modes. This is achieved thanks to the flexibility of the implemented detector, the optimizations made in acquisition parameters, such as energy filtering settings, and the efficiency of the developed custom approach used for electron data post-processing. Through this work, it is demonstrated that with a single DED assisted by an orientable support, it is possible to perform multiple advanced microstructural characterizations of both bulk samples and thin foils in the same SEM.
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All authors Nohayla El-Khairaoui, Julien Guyon, Nathalie Gey, Luc Morhain, Nabila Maloufi
Statistical Mechanics · Cross-listed from physics.ed-ph
Physics in the Public Square: University Extension as a Strategy for Integrating Physics Education and Science Communication
Andre A. A. Marinho, Gisele B. Freitas and Camila B.C. da Silva
University extension activities play a fundamental role in bridging the gap between academia and society by fostering the socialization of scientific knowledge. This study reports and analyzes an outreach activity conducted in a public space, involving undergraduate students enrolled in Physics I, Physics III, and Physics IV courses within the Physics Teacher Education Program at the State University of the Tocantina Region of Maranhao (UEMASUL). The activity was developed through the design and presentation of didactic experiments using low-cost materials. Its main objectives were to disseminate fundamental physics concepts to the community, stimulate public interest in science, and provide pre-service teachers with a formative experience integrating theory, practice, and social responsibility. Data were collected from questionnaires adminisvelopment of communication skills, and the strengthening of the university's social role, while also fostering scientific curitered to visitors (n = 52). The results indicate that the activity significantly contributed to student learning, the deosity among participants.
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Quantum Gases · Cross-listed from quant-ph
Dissipation-assisted preparation of Floquet-Laughlin states in superconducting circuits
Luis C. Steinfadt, André Eckardt and Francesco Petiziol
Fractional Chern
insulators (FCIs) are
lattice analogs of fractional
quantum Hall systems, where the interplay of strong interactions with a frustrated tunnelling kinetics leads to the emergence of a gapped ground state with long-range
entanglement and anyonic excitations. The highly correlated nature of such systems makes their adiabatic preparation challenging already beyond the minimal system size of two particles. Considering Floquet implementations of the bosonic Harper-Hofstadter-Hubbard model of few
photons in superconducting
circuits, we design protocols for the driven-dissipative stabilization of its FCI ground state at half filling via
quantum bath engineering. Dissipation control is achieved through the coupling to driven leaky cavity modes, which realize a tuneable artificial environment having the Floquet-FCI as its approximate fixed point. For systems of two, three and six particles, we show numerically how the flexibility of the control scheme further allows for the detection of fractional
quantum Hall signatures in the stabilized steady states, including bulk incompressibility,
Hall response and the trapping of fractional charges. Our results provide a concrete pathway to dissipation-assisted preparation of strongly correlated states in
quantum simulators.
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Soft Condensed Matter
Coherent modeling of double-folded ring polymers and their underlying random tree structure
Pieter H. W. van der Hoek, Angelo Rosa, Elham Ghobadpour et al. (+1 more)
Topologically constrained genome-like
polymers often double-fold into tree-like configurations, which can be modelled on the level of folded (ring)
polymers or on the level of the underlying random trees. For both descriptions, we have recently obtained expressions for the configurational
entropy in ensembles with controlled branching activity. Here we demonstrate that they are equivalent up to a contribution originating from the number of distinct wrappings of a single tree. This allows us to develop a coherent framework for freely switching between the two representations. Importantly, the equivalence extends to interacting systems provided the interactions are treated consistently on the tree and on the ring level. To demonstrate the utility of the scheme, we introduce a generalization of the Amoeba Monte Carlo
algorithm capable of generating the required ensembles of trees with fluctuating sizes. While the tree
algorithm reproduces results obtained by dynamic simulations of the corresponding ring model, it is $O(N)$ faster for the purpose of sampling static properties and leverages the utility of the ring model for the study of dynamical properties, when used for the preparation of equilibrated starting states.
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All authors Pieter H. W. van der Hoek, Angelo Rosa, Elham Ghobadpour, Ralf Everaers
Statistical Mechanics
Ordering, correlation functions and phase transitions in molecular systems
Yashwant Singh
Although the classical density functional theory (DFT) of inhomogeneous fluids was formulated more than four decades ago, its application to broken
symmetry phases of molecular systems remained a challenge. Approximate free energy functionals proposed in the past failed to give accurate description of relative stability of phases, phase transitions, and of properties arising due to broken
symmetry. In a DFT pair correlation functions (PCFs) play a fundamental role. While in the case of homogeneous fluids, PCFs are routinely determined using experimental, theoretical or simulation methods, determination of PCFs of broken
symmetry phases remained a problem. Breaking of
symmetry at the transition point gives rise a new contribution to correlation functions which may differ significantly from that of the coexisting higher
symmetry phase. We review methods which have been developed in the last few years to calculate PCFs of broken
symmetry phases and their inclusion in the expressions of the grand potential and the intrinsic free-energy. This leads to formulation of an exact DFT. We describe application of the theory to freezing of variety of fluids into ordered phases and transition from an ordered phase of higher
symmetry to a phase of lower
symmetry. Comparison of results found from different versions of DFT and simulations reveal their accuracy. A brief description of basics of statistical mechanics is included to make the article self-contained.
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Mesoscale and Nanoscale Physics
Kapitza-like modulation of near-field radiative heat transfer
Mauro Antezza
We introduce a Kapitza-like mechanism for the near-field radiative heat transfer and show that fast modulation of any parameter controlling the flux, such as the
vacuum gap or a material response, produces a quadratic, time-averaged correction in the slow thermal dynamics. This correction splits into a frequency-independent static term and a low-pass dynamical term, yielding sizable modulation-induced temperature shifts and modified effective thermal conductances that can stabilize or destabilize the steady state. Applying the theory to gap modulation between SiC slabs, we derive analytical scaling laws and predict temperature shifts that are fully measurable with existing experimental platforms, requiring only readily accessible low modulation frequencies of order $\Omega \approx 10^4~\mathrm{rad/s}$. Our results establish a thermal analog of the Kapitza mechanism and provide a general route for controlling radiative heat flow in micro- and nanoscale platforms.
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Materials Science
Tuning the Charge Transfer of Transition Metal Dichalcogenides via Misfit Layer Compounds
Hugo Le Du, Ludovica Zullo, Justine Cordiez et al. (+16 more)
Misfit layer compounds (MLCs) are a versatile platform for exploring the electronic phase diagram of two dimensional (2D) materials beyond the limits of conventional gating techniques. This work demonstrates the precise tunability of electron doping in NbSe2 monolayers through chemical alloying within the rocksalt layer of (LaxPb1xSe)1.14(NbSe2)2
heterostructures. By combining first principles density functional theory (DFT) calculations with angle resolved photoemission spectroscopy (ARPES), we prove that the rocksalt unit acts as an universal electron donor. We show that varying the La Pb ratio results in a rigid
Fermi level shift, still preserving the NbSe2 electronic structure. Crucially,
photon energy dependent ARPES confirms that the NbSe2 layers nearly maintain their intrinsic 2D character and orbital identity within the three dimensional misfit. This study establishes MLCs as a reliable platform for engineering emergent states in 2D transition metal dichalcogenides through precise stoichiometric control.
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All authors Hugo Le Du, Ludovica Zullo, Justine Cordiez, Robin Salvatore, Giovanni Marini, Marie Hervé, Debora Pierucci, Shunsuke Sasaki, Florent Pawula, Etienne Janod, Chiara Bigi, Marta Zonno, François Bertran, Thomas Jaouen, Patrick Le Fèvre, Matteo Calandra, Laurent Cario, Tristan Cren, Marie D Angelo
Statistical Mechanics
Energy-Weighted Site Percolation in Two Dimensions
Sayan Sircar and Kabir Ramola
We study a generalization of two-dimensional site percolation by assigning an energy cost $\varepsilon$ to bonds between nearest-neighbor occupied sites. This leads to a competition between
entropy-driven cluster growth and energetic suppression (or enhancement) of connectivity. Varying $\varepsilon$ continuously interpolates between dense
ferromagnetic-like clusters, ordinary classical percolation, and a dilute regime of minimally connected isolated clusters. Using Monte Carlo simulations and real-space renormalization-group (RG) methods, we show that bond energy shifts the percolation threshold smoothly. We define an energy-weighted correlation length that remains finite at the classical site occupation threshold ($p_c(\varepsilon=0)$) and shrinks with increasing $\varepsilon$, capturing the energetic suppression of large-scale connectivity. The cluster size distribution exhibits an energy-dependent cutoff that drives the transition from percolation-like clusters to isolated clusters. A real-space RG with Kadanoff block recursions reveals a systematic
evolution of the correlation-length exponent $\nu$ from $\nu=1/2$ (dense clusters) to $\nu=4/3$ (classical percolation), approaching $\nu=1$ (minimally connected isolated clusters), in agreement with Coulomb-gas predictions for loop models where bond energy renormalizes loop fugacity. For large values of \(\varepsilon\) (isotropic case), the suppression of nearest-neighbor bonds results in the emergence of
antiferromagnetic sub-
lattice ordering at high densities. Additionally, anisotropic bond energies lead to directionally selective cluster growth. Finally, we also discuss a
lattice gas RG approach and scenarios where bond energy is renormalized across different scales.
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Quantum Gases
Jones-Roberts solitary waves and the onset of rotation in a spherical surface condensate
Noel Cuadra, Alberto Villois, Thomas Gasenzer et al. (+1 more)
The nonlinear excitations underlying the onset of rotation in a dilute Bose-Einstein condensate confined to a thin spherical shell are studied. These excitations correspond to solitary waves rotating about the sphere at constant angular speed: at low speeds they appear as dipoles of singly quantized
vortices with opposite circulation, while at higher speeds they evolve into
vortex-free Jones-Roberts
solitons. With further increase of the angular speed, these excitations hybridize with equatorially confined modes whose azimuthal wave number is set by the sphere radius measured in units of the healing length. The propagation speed of these modes is shown to play the role of a Landau critical velocity, thereby setting the upper limiting angular speed of the entire Jones-Roberts family.
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All authors Noel Cuadra, Alberto Villois, Thomas Gasenzer, Davide Proment
Mesoscale and Nanoscale Physics
Strong nanomechanical Duffing nonlinearity and interactions induced through cavity optomechanics
Jesse J. Slim and Ewold Verhagen
Nonlinearity is a key resource in both classical and
quantum signal processing. Nonlinear nanomechanical elements have found applications ranging from sensing to computing, while networks of nonlinear resonators, as well as nonlinearly coupled networks of linear resonators, constitute promising platforms for simulating complex dynamics. Here, we experimentally demonstrate an approach to realizing strong mechanical nonlinearity in nanomechanical resonators, fully controlled through optical
laser drives. The mechanism exploits the nonlinearity of the radiation-pressure interaction in a cavity optomechanical system, which gives rise to a nonlinear optical spring effect. The resulting Duffing nonlinearity is conveniently tunable in strength via pump
laser power, while its sign is controlled by
laser detuning. Moreover, we demonstrate that the nonlinear optical spring mediates effective interactions between mechanical modes coupled to a common cavity, inducing tunable nonlinear interactions between them that impact spectral response and dynamics. These results establish cavity optomechanics as a versatile and in-situ reconfigurable platform for engineering nonlinear dynamics in resonators and networks.
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Soft Condensed Matter
Coalescence of Polymer Droplets Moving on a Surface with Stiffness Gradient
Divyansh Tripathi, Vimal Kishore, Panagiotis E. Theodorakis et al. (+1 more)
Here, we study the coalescence of two droplets that are moving in the same direction on a soft surface; the motion of the droplets is caused by a gradient in the surface stiffness. As reference, stationary coalescence of the same droplets is also studied on the corresponding uniform surfaces for different stiffness values. To describe the coalescence phenomenon on a surface with stiffness gradient, a relevant range of velocity ratios of the leading and the trailing droplet was considered to elucidate the effect of this parameter on coalescence. Moreover, to analyze the dynamics of the process, the temporal growth of the bridge height $(h)$ was investigated, which follows a power law $(h \sim t^{\alpha})$, before eventually attaining a constant value. The obtained values of $\alpha$ show a transition from a higher to a lower value as a function of time, pointing to the presence of two distinct power-law growth regimes, where the transition signifies the crossover from the capillarity-dominated regime to the viscoelasticty-dominated regime of coalescence. In addition, varying attractive strengths for droplet–droplet and intra-droplet interactions were considered. The results indicate that both the dynamics and the degree of the coalescence strongly depend on these interaction parameters. Thus, we anticipate that our results will shed more light on the durotaxis-driven coalescence of polymeric droplets for various relevant system parameters, which will have practical implications for applications ranging from microfluidics to ink-jet printing, where substrate properties may vary. In addition, results may add to the fundamental understanding of the interactions among multicellular aggregates moving on biological surfaces.
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All authors Divyansh Tripathi, Vimal Kishore, Panagiotis E. Theodorakis, Swarn Lata Singh
Strongly Correlated Electrons
Quantum geometry induced anomalous chiral transport and hidden symmetry breaking in centrosymmetric 2M-WS2
Hang Cui, Shao-Bo Liu, Erqing Wang et al. (+16 more)
Chirality, a widely existing material property in nature involving the breaking of the left-right
symmetry, has profound influences in various fields of natural sciences. Nonlinear response, such as electronic magnetochiral anisotropy (eMChA), has been recognized as a sensitive probe for the effects of
symmetry breaking and nontrivial
quantum geometries in solids. So far, observations of eMChA have primarily been limited to inversion-
symmetry broken materials. Here, we report a remarkable
chiral transport in centrosymmetric candidate topological
superconductor 2M-WS2 flakes observed via second-harmonic generation under an out-of-plane
magnetic field. More importantly, the eMChA becomes significant around the crossover temperature TFL ~ 25 K from the
Fermi liquid (FL) to strange metal (SM) in the normal state, which interestingly echoes with the anomalously large Nernst response at the same temperature in bulk 2M-WS2. These observations reveal a direct correspondence between the nonlinear response, Nernst response, and FL-SM transition in 2M-WS2. Theoretical analysis indicates that nontrivial
quantum geometry is behind the simultaneous response of eMChA and Nernst effects in 2M-WS2 and the contribution from the orbital
magnetic moment at the
Fermi surface becomes significant during the FL-SM transition. Based on first-principles calculations, a thick-layer-sliding mechanism with minimal energy gain in 2M-WS2 provides one possibility for the generation of such nontrivial
quantum geometry. The intertwined physics of remarkable eMChA, Nernst response, and FL-SM transition make 2M-WS2 a rare
quantum platform to study the
chiral transport and unexplored phenomena in strange metals, which may shed light on the trans-century, unresolved scientific issue in unconventional high-temperature superconductivity.
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All authors Hang Cui, Shao-Bo Liu, Erqing Wang, Mingxiang Pan, Yuqiang Fang, Ning Ma, Wenlong Liu, Di Chen, Yu Zhang, Yuanjun Song, Tingting Hao, Jiankun Li, Jian Cui, Ya Feng, Haiwen Liu, Fuqiang Huang, Huaqing Huang, X.-C. Xie, Jian-Hao Chen
Materials Science
Why hole polaron formation on oxygen is limiting the Fermi level in Fe acceptor doped BaTiO$_{3}$ under oxidizing conditions
Mohammad Amirabbasi, Emre Erdem, Denis Sudarikov et al. (+3 more)
Oxidizing Fe-doped BaTiO$_3$ is commonly expected to convert substitutional Fe$^{3+}$ acceptors into formal Fe$^{4+}$ centers. Yet, the experimentally accessible picture based on electron-paramagnetic resonance (EPR) is dominated by Fe$^{3+}$-related signatures, while Fe$^{4+}$ is not a straightforward observable. Here we show that this apparent discrepancy reflects the preferred location of the oxidizing hole: not on Fe, but on oxygen. Using density-functional theory with with occupation-
matrix control and a piecewise-linearity-based Hubbard correction (DFT+$U$) for O-2$p$ states, we find that an oxygen-centered hole polaron is forming a Fe$^{3+}$-O$^{-}$ complex that is lower in energy than the formal Fe$^{4+}$ configuration. Our results identify ligand-hole formation as a favorable charge-compensation mechanism in oxidized Fe-doped BaTiO$_3$ and provide an explanation for the predominance of Fe$^{3+}$-based centers in spectroscopy. More broadly, they show how oxygen polarons can limit
Fermi-level shifts and control the electronic response of acceptor-doped ferroelectric perovskites.
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All authors Mohammad Amirabbasi, Emre Erdem, Denis Sudarikov, Jochen Rohrer, Andreas Klein, Karsten Albe
Soft Condensed Matter
Modulating hydrodynamic flow by modifying the active patch of a colloid
Om Vandra, Suhal Siva Ratan T. N., Hemant Giri et al. (+4 more)
We have developed a simulation model to study the hydrodynamic flow fields around Brownian colloidal particles with an active surface patch. Hydrodynamics is introduced by modeling low-Reynolds-number fluid flows around a colloid using multi-particle collision (MPC) dynamics and allowing momentum exchange between the MPC fluid and the colloid. This approach provides good estimates of both near- and far-field flows around the colloid. The size of the active patch is varied to generate different fluid flow fields around the colloid. In this framework, the fluid in the vicinity of the active patch is driven radially away from (or toward) the surface, and an equal and opposite momentum is imparted to the colloid to ensure momentum conservation. The resulting surface-driven flow generates self-propulsion of the particle, thereby converting an otherwise Brownian colloid into an active Brownian particle. Interestingly, as we systematically vary the surface area of the active patch on the colloid, the nature of the generated flow field changes from that of a pusher to a puller. To model such surface activity-driven flows, we developed a hybrid boundary condition that ensures a no-slip condition while incorporating momentum exchange between the flowing fluid and the colloid surface. This scheme integrates the advantages of bounce-back and
stochastic boundary conditions while mitigating their respective limitations. Thus, in future studies, the effective hydrodynamic interactions between an active and a passive colloid, or between two active colloids, can be modulated by adjusting the size of the active patch.
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All authors Om Vandra, Suhal Siva Ratan T. N., Hemant Giri, Manish Modani, Vijay Chikkadi, Raghunath Chelakkot, Apratim Chatterji
Strongly Correlated Electrons
Pressure Effects on CeMnSi: Evolution of Ce 4f and Mn 3d Electronic States and Negative Thermal Expansion
Sae Nishiyama, Haruka Mima, Jun-ichi Hayashi et al. (+6 more)
We investigated pressure effects on the nontrivial heavy-
fermion antiferromagnet CeMnSi by means of electrical resistivity and powder X-ray diffraction. With increasing pressure, the
antiferromagnetic order of Mn (T_N ~ 240 K at ambient pressure) is rapidly suppressed and disappears at P_c ~ 1.3 GPa. Instead, a pressure-induced anomaly appears at T_M ~ 97 K and shifts to higher temperatures with increasing pressure. The switching of the Mn
magnetic state may reflect a modification of the
magnetic symmetry of the system, which could influence the stability of the heavy-
fermion state. In the low-pressure region, non-
Fermi-
liquid-like behavior characterized by nearly T-linear resistivity is observed around 0.7 GPa. In addition, the resistivity shows a marked reduction below T_M and a qualitative change toward more metallic behavior above the structural transition pressure P_s ~ 5.7 GPa. At ambient pressure, CeMnSi exhibits negative thermal expansion below ~40 K, which is absent in LaMnSi, supporting the formation of a heavy-
fermion ground state.
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All authors Sae Nishiyama, Haruka Mima, Jun-ichi Hayashi, Keiki Takeda, Chihiro Sekine, Yoshiya Uwatoko, Hiroki Takahashi, Hiroshi Tanida, Yukihiro Kawamura
Materials Science
Short-range order in the CoCrFeMnNi high-entropy alloy from cluster expansion
Wei Chen, Gian-Marco Rignanese and Geoffroy Hautier
We investigate the short-range order (SRO) and phase stability of the equiatomic CoCrFeMnNi high-
entropy alloy using cluster expansion supplemented by an eigen-decomposition analysis of the SRO parameters. Our results reveal that the primary ordering behavior is determined by strong Cr-Cr repulsive interactions, complemented by attractive heteroatomic Cr-$X$ pairs in the first nearest-neighbor shell. This chemical affinity is consistent with the emergence of ordered local environments and appears to be a major contributor to the primary order-disorder transition. At lower temperatures, the spectral SRO analysis suggests two additional lower-temperature instabilities: a collective ordering instability and an Fe-rich local clustering instability.
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Materials Science
First-principles investigation of small polarons in rhombohedral NaNbO$_{3}$
Mohammad Amirabbasi, Lorenzo Villa, Elaheh Ghorbani et al. (+2 more)
Sodium niobate (NaNbO$_{3}$) is a perovskite
oxide and a key component of emerging lead-free antiferroelectric capacitors for high-energy-density applications. However, its performance can be hindered by irreversible phase transitions and leakage currents associated with low electrical resistivity. Defect and doping engineering offers a potential way to overcome these problems, but its use requires a detailed understanding of electronic, ionic, and polaron charge-compensation mechanisms, where the role of polarons remains largely unexplored. Here, we investigate the stability of small hole and electron polarons in rhombohedral NaNbO$_{3}$, which is a structurally well-defined model system that avoids
lattice-dynamical instabilities. Trapping energies are calculated using density-functional theory corrected by a Hubbard $U$, using the enforced-piecewise-linearity approach including finite-size scaling. For the small hole-polaron centered on O-2$p$ orbital, we find a trapping energy of $-$0.65 (eV) and an adiabatic migration barrier of 0.32 (eV) determined by nudged-elastic-band calculations. In contrast, we show that excess electrons do not self-trap on Nb-4$d$ orbitals, reflecting weak electron-
phonon coupling in the conduction band
manifold. These results identify oxygen as an intrinsic hole trap in NaNbO$_{3}$ and highlight the importance of including hole polarons in defect models of NaNbO$_{3}$-based electroceramics.
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All authors Mohammad Amirabbasi, Lorenzo Villa, Elaheh Ghorbani, Jochen Rohrer, Karsten Albe
Statistical Mechanics
Dynamic Coulomb disorder and eikonal attenuation of a quantum particle in a classical one-component plasma
Yury A. Budkov
We extend the static theory of disorder-induced exponential decay of the averaged Green function of a
quantum charged particle in a classical one-component
plasma to the dynamic regime. The central object of the theory is not the Anderson localization length in the strict Lyapunov sense, but the eikonal attenuation scale of the disorder-averaged propagator. The temporal
evolution of the ionic density fluctuations is incorporated within the random phase approximation, and the dynamic potential correlator is derived from the fluctuation–dissipation
theorem and the Kramers–Kronig relations. Within the eikonal approximation, the effective disorder strength is expressed through the longitudinal dielectric function of the ion
plasma. For particles moving faster than the ion thermal speed, the static Coulomb logarithm is recovered, with the large-distance cutoff replaced by the dynamic scale $v/\omega_{pi}$. For slow particles, the Coulomb logarithm disappears completely and the disorder strength becomes proportional to the velocity. Consequently, the controlled weak-disorder attenuation scale becomes proportional to $k$, instead of the usual quasi-static $k^2$ law. We also show that the full saddle-point problem in a dynamic medium contains an additional dependence on the saddle variable through the effective velocity $v_s=v/s$. In the slow-particle strong-saddle sector this self-consistency leads to a saturation scale $\ell\sim g^{-1/2}$, where $g$ is the coefficient in $G_{\rm dyn}(v)=gk$. Building on the same dynamic formalism, we evaluate the mutual coherence function in the slow weak-disorder branch and show that the transverse coherence length obeys the same parametric relation $\rho_c\sim\lambda_D\sqrt{\ell/L}$ as in the static case.
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Materials Science
High-Density Horizontal Arrays of Single-Chirality Carbon Nanotubes
Yanzhao Liu, Zilong Qiu, Yuguang Chen et al. (+18 more)
Highly ordered high-density arrays of single-chirality single-walled carbon nanotubes (SWCNTs) are greatly desired for exploring the intrinsic anisotropic properties and collective performance of such 1-dimensional (1D) nanomaterials. Here we present a Marangoni flow-induced self-assembly (MISA) strategy to fabricate monolayered SWCNT arrays achieving a packing density of ~200 ${\mu m}^{-1}$ and a 2-dimensional order parameter ($S_{2\mathrm{D}}$) of ~0.95. Relying on its general compatibility with both organic and aqueous dispersions, we prepare single-chirality and enantiomer-pure SWCNT arrays from organic and aqueous dispersions resulting from the sorting processes. The anisotropic optical and electrical properties of the arrays are demonstrated by the polarization-dependent Rabi splitting as well as polarized near-infrared light emission and detection. With the great tolerance to solutions, substrates, and materials, as well as the feasibility and controllability, MISA shows great potential in the assembly of 1D nanomaterials.
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All authors Yanzhao Liu, Zilong Qiu, Yuguang Chen, Nie Zhang, Bing Han, Huimin Yin, Bojun Liu, Min Lyu, Zhihong Li, Yiran Ma, Jian Sheng, Jiahui Shao, Zeyao Zhang, Li Ding, Hao Hong, Chuanhong Jin, Sheng Wang, Kaihui Liu, Xiaowei He, Lian-Mao Peng, Yan Li
Statistical Mechanics · Cross-listed from physics.plasm-ph
Localization of a quantum particle in a classical one-component plasma: fluctuation-induced random potential, localization length and mutual decoherence
Yury A. Budkov
We develop a microscopic theory of disorder-induced attenuation and mutual coherence degradation for a
quantum particle in a classical one-component
plasma. The random potential originates from
equilibrium thermal fluctuations of the ionic charge density within the random phase approximation. Its correlator retains an unscreened $1/r$ tail, leading to a Coulomb logarithm in the eikonal localization scale $\ell(k)$. In the weak-disorder regime $\ell(k) \propto k^2 / \ln(\kappa L)$, while in the strong-disorder limit $\ell \propto (\ln(\kappa L))^{-1/3}$. Building on the same disorder model, we evaluate the mutual coherence function (Cooperon) of an electron beam and derive a closed analytical expression for the phase structure function $D_\phi(\rho)$. At large transverse separations the coherence decays as a power law $\gamma(\rho)\sim \rho^{-\eta}$, with an exponent determined by the disorder strength. The transverse coherence length $\rho_c$ satisfies a scaling relation $\rho_c \sim \lambda_D \sqrt{\ell/L}$, linking the eikonal attenuation scale with the loss of
quantum coherence. Numerical estimates for aqueous electrolytes under transmission electron microscopy conditions are given. A relativistic extension confirms that the same scaling holds for relativistic beams, with the eikonal coupling given by $A_{ m rel}=1/(\hbar v)$ and approaching the finite high-energy limit $1/(\hbar c)$.
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Materials Science
Characterisation of fire-damaged batteries,implications for recycling
Wafaa AlShatty, Tom Dunlop, Rhys Charles et al. (+2 more)
As lithium-ion battery demand grows, so do fire safety challenges. Despite this, research on fire-damaged batteries remains limited. This study explores the distribution of valuable metals (such as Ni, Mn, Co, Cu) in two types of waste derived from lithium-ion nickel-manganese-cobalt
oxide batteries (NMC811), black mass (BM) and fire-damaged waste (FD). It emphasizes that cobalt, manganese, and nickel-rich NMC811 particles are predominantly found in smaller particle size fractions (<125 microns), where they can account for up to 85 percent of total metal content. Fire-damaged (FD) batteries show a similar, though less pronounced, trend. Evidence of structural degradation suggests that fire temperatures exceeded 500{\deg}C; however, the presence of residual organic binders indicates that heat was unevenly distributed during the fire. FD batteries become friable and easily fragment into fine particles, which can hinder the effective separation of copper and aluminium current collectors, increasing their presence in processed material. The inclusion of FD batteries in standard BM processing introduces variability in output composition, potentially lowering the concentration of high-value NMC811 materials present. To maintain product quality and recycling output values, it is recommended that FD batteries are processed separately. Alternatively, particle size separation may allow for tailored outputs aligned with specific customer requirements.
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All authors Wafaa AlShatty, Tom Dunlop, Rhys Charles, Davide Deganello, Jenny Baker