Other Condensed Matter
Exact Phase-Space Rotation in the Trapped Quantum Calogero Model
Akash Sarkar
We develop a microscopic phase-space description of the
quantum Calogero model in the presence of an external harmonic confining potential. Building on the
quantum Lax-pair structure, we construct a Hermitian Wigner operator whose expectation value obeys the exact phase-space
evolution equation d_t rho + lambda d_x rho - Omega^2 x d_lambda rho = 0 for arbitrary initial states and to all orders in the interaction strength. The resulting dynamics is a rigid rotation in phase space with period 2 pi/Omega, providing a microscopic realization of the isochronous dynamics of the trapped Calogero model. We further show that the moments of the phase-space density form rotating multiplets rather than independent conserved quantities. In particular, within the quadratic sector, the unique conserved combination is proportional to the trapped
Hamiltonian, providing a nontrivial consistency check of the construction. In the limit Omega -> 0, the equation reduces to the exact free-streaming equation of the untrapped model.
Read the full abstract ▾
Materials Science · Cross-listed from math-ph
The inverse problem of time-dependent density functional theory on the torus
Asbjørn Bækgaard Lauritsen, Mathieu Lewin and Jakob Oldenburg
We prove that, for any given sufficiently regular one-particle density, there exists a unique external potential for which the solution to the many-body Schrödinger equation has this prescribed density. This implies in particular that one can exactly reproduce the time-dependent density of an interacting system using non-interacting electrons, which is at the heart of time-dependent density functional theory. Our result covers the Coulomb interaction and densities arising from extended
nuclei.
Read the full abstract ▾
Materials Science
Time-Dependent Density Functional Theory with Coulomb Interactions
Asbjørn Bækgaard Lauritsen, Mathieu Lewin and Jakob Oldenburg
We provide the first fully rigorous justification of time-dependent density functional theory in the continuum: Given a time-dependent density, we prove that there exists an external potential, unique up to a time-dependent constant, such that the corresponding Schrödinger equation reproduces the given density. This potential can be obtained with an iteration scheme. Our argument covers Coulomb interactions and does not need any Taylor expansion in time. It instead requires analyticity in space for the density and potential, which is compatible with extended
nuclei.
Read the full abstract ▾
Materials Science
Water, vacancies, and competing exchange interactions in Prussian blue analogues: a neutron diffraction study of field and dehydration-driven magnetic transitions
N. S. Dhami, C. V. Colin, V. Nassif et al. (+5 more)
We report a
neutron diffraction study of the structural and
magnetic properties of a family of ferro- and ferrimagnetic Prussian blue analogues (PBAs), $A_4$[Fe(CN)$_6$]$_{2.7}$ ($A$ = Co, Mn, Ni), Rb$_2$Ni$_4$[Fe(CN)$_6$]$_{3.3}$, and Mn$_4$[Cr(CN)$_6$]$_{2.7}$, as a function of temperature (2–450~K) and applied
magnetic field. All bimetallic compounds of the Fm$\overline{3}$m family exhibit a broad diffuse feature at low scattering angle, which we identify, through comparison with the cation-stabilized Rb$_2$NiFe framework, as an intrinsic signature of correlated vacancies and their associated interstitial water. High-temperature diffraction reveals a continuous crossover from positive to negative thermal expansion in CoFe and MnFe upon dehydration, while NiFe remains structurally robust up to 450~K. At low temperature, all compounds order in a collinear ferrimagnetic state with propagation vector $\mathbf{k}=(0,0,0)$, except MnFe, which adopts a partially frustrated
magnetic structure with $\mathbf{k}=(1,0,0)$. A moderate
magnetic field of $B_c = 1.3$~T drives a
spin reorientation in MnFe toward the collinear $\mathbf{k}=(0,0,0)$ ferrimagnetic state common to the other compounds; the same transition is independently induced by dehydration. A minimal Heisenberg model shows that this transition results from a near-compensation between antiferromagnetic Mn–Fe coupling and a geometrically frustrated antiferromagnetic Mn–Mn interaction on the face-centered-cubic Mn sublattice, placing MnFe in the vicinity of a
magnetic compensation point. These results resolve a longstanding ambiguity in the interpretation of the Fe $K$-edge XMCD response of MnFe-based PBAs, and establish water content as a key parameter controlling both the structural and
magnetic stability of this family of materials, with direct relevance to their use as battery electrodes.
Read the full abstract ▾
All authors N. S. Dhami, C. V. Colin, V. Nassif, O. Fabelo, T. Nait, A. Bleuzen, A. Bordage, V. Balédent
Statistical Mechanics · Cross-listed from quant-ph
Restart and first detection in a lackadaisical quantum walk with flat-band localization
Debraj Das
We study
stochastic and sharp restart in a one-dimensional lackadaisical discrete-time
quantum walk with self-loop weight $\ell$. In the absence of restart, the dynamics has a flat band responsible for intrinsic localization and two dispersive bands supporting ballistic propagation. We compare two initially localized
benchmark states: a flat-band-active state with finite flat-band overlap and a flat-band-dark state with zero flat-band overlap. For
geometric stochastic restart with per-step restart probability $q$, the stationary mean-squared displacement scales as $q^{-2}$ as $q\to0$. In the same limit, the restart-site occupation probability approaches the restart-free intrinsic localized value for the flat-band-active state, whereas for the flat-band-dark state it vanishes as $q\ln(1/q)$. For power-law restart, where $p_m\propto m^{-s}$ is the probability that the waiting time to the next restart is $m$ steps, a normalized stationary site-occupation distribution exists only for $s>2$, while the stationary absolute spatial moment of order $p$ is finite only for $s>p+2$. In the regime $1<s\leq2$, at every fixed
lattice site, the flat-band-active occupation converges to the intrinsic flat-band profile, while the flat-band-dark occupation tends to zero. We also consider monitored first detection with sharp restart, in which the walk is reinitialized after a fixed number $r$ of consecutive unsuccessful measurements. For fixed $r$, the mean first-detected-passage time of the flat-band-active state exhibits a minimum at an intermediate self-loop weight, whereas the flat-band-dark state approaches a ballistic detection limit as $\ell\to\infty$.
Read the full abstract ▾
Strongly Correlated Electrons
Real-time Dyson expansion for the nonequilibrium $GW$ approximation: Correlated spectra and dependence on the reference propagator
Erik Schroedter, Jan-Philip Joost, Michael Bonitz et al. (+1 more)
Electronic spectra provide direct insight into the excitations and correlations of condensed matter systems. Their description requires electron correlations beyond mean field. In
equilibrium, the $GW$ approximation has become the method of choice for many materials. Extending this approximation to nonequilibrium, however, is challenging. Full two-time $GW$ simulations within the nonequilibrium Green's functions approach scale at least cubically with propagation time, whereas improved scaling schemes such as time-local (adiabatic) approximations or the generalized Kadanoff–Baym ansatz usually retain only mean-field character in the spectra. The recently introduced real-time Dyson expansion recovers dynamical correlations in the spectrum at time-linear cost, but has so far been restricted to the second-order Born approximation with mean-field reference propagators. Here we formulate and implement the RT-DE for the nonequilibrium $GW$ self-energy with reference propagators of general form whose off-diagonal
evolution is time local. In particular, we assess Hartree–Fock propagators, propagators with statically screened exchange with nonequilibrium screening, and a correlated propagator based on the Hartree–Fock GKBA.
Benchmarks against exact diagonalization for a driven two-band
lattice model with long-range interactions show that the mean-field and statically screened references yield the most accurate spectra, including satellite structures absent at mean-field level, whereas the GKBA-based approach best captures scattering-induced occupation dynamics, but artificially broadens and splits spectral peaks. When applied to large systems that are beyond the reach of exact methods, the scheme resolves the excitonic replica of the valence band and satellites identified as
exciton shake-up, as well as their reshaping with increasing excitation density.
Read the full abstract ▾
All authors Erik Schroedter, Jan-Philip Joost, Michael Bonitz, Vojtech Vlcek
Materials Science
Edge-Dominated Twist Mechanics at van der Waals Interfaces
Yifan Shao, Zhaoheng Zhang, Hao Li et al. (+5 more)
Despite the pivotal role of twist in modulating physical properties at van der Waals (vdW) interfaces, the mechanics governing torsional response remain poorly understood. Here, we probe twist mechanics at homo- and heterogeneous vdW interfaces, together with their sliding behaviors within a unified experimental framework. For both systems, the peak torque scales nearly linearly with contact area, in contrast to predictions from linear elastic and rigid models. Remarkably, while the sliding friction of the two interfaces diverges by over three orders of magnitude owing to different scaling laws, the corresponding torque follows the same linear scaling and differs by only about twenty-fold. Large-scale atomistic simulations reveal an edge-dominated yielding mechanism for torsional motion, wherein elastic reconstruction shifts the effective load-bearing region toward the edges, eliminating torque from the contact interior. This mechanism contrasts with the bulk-mediated stress transmission governing translational sliding, a distinction rooted in the different loading geometries inherent to the two motion modes, where torsional loading necessitates perimeter actuation, whereas sliding enables center-driven loading. This
symmetry-imposed divergence demonstrates that translational and torsional properties cannot be predicted from one another at vdW interfaces, providing critical insights for the design of dynamically reconfigurable micro- and nanoelectromechanical devices.
Read the full abstract ▾
All authors Yifan Shao, Zhaoheng Zhang, Hao Li, Oded Hod, Michael Urbakh, Quanshui Zheng, Xiang Gao, Deli Peng
Soft Condensed Matter
Thermomechanics of dense granular materials: a particle-scale perspective
Matthew R. Kuhn
The paper presents a broad thermomechanic framework for the isothermal rate-independent constitutive behavior of dense granular materials. The essential quantities in this framework are directly measurable in discrete element (DEM) simulations: free energy, dissipation, stress, and strain. The paper proposes that energy and dissipation are governed by two sets of internal variables: fabric variables that control the reversible stiffness and structure variables associated with internal sliding. The relevant fabric variables are identified and measured with simulations. Two hypotheses are considered for the structure variables: the macro-scale irreversible strain and an aggregate measure of the micro-scale frictional forces among sliding contacts. Both hypotheses are tested with simulations, which allow direct calculation of the internal variables. The paper then demonstrates the manner in which the measured variables are applied in incremental constitutive models. Among other findings are the following. (1) Dissipation from contact sliding is pervasive and occurs in all directions of incremental loading. (2) Contact motions are not reversed by a reversal of the strain direction, and contacts continue to slide when loading is reversed. (3) The free energy can not be assumed smoothly differentiable; instead, Gâteaux derivatives must be used with irreversible effects. (4) Basic assumptions of elastoplasticity are contravened: no region of purely reversible strain exists, no uniform yield direction exists, no uniform flow direction exists, and irreversible strain is not proportional to the projected total strain. A three-mechanism elastoplasticity model, however, closely fit the DEM results, and methods are demonstrated for quantifying the model. The results emphasize that advanced constitutive models are needed for capturing the general incremental behavior of granular materials.
Read the full abstract ▾
Strongly Correlated Electrons
Positive Temperature Coefficient of Anisotropy due to $d^6L$ Groundstate in $\epsilon$-Fe$_2$O$_3$
Rachel Nickel, Kurt Kummer and Johan van Lierop
Positive anisotropy temperature coefficients ($dK/dT>0$) usually arise from hybridization between
magnetic 3d states and strongly
spin-orbit-coupled (SOC) subsystems. Yet $\epsilon$-Fe$_2$O$_3$ shows $dK/dT>0$ (125-200~K) without an obvious SOC partner. We study pure and Cr-doped (with weakened Fe-O hybridization) $\epsilon$-Fe$_2$O$_3$ across the transition from low temperature incommensurate to high-anisotropy
magnetic phases. We identify a $d^6L$ groundstate in $\epsilon$-Fe$_2$O$_3$ while reduced hybridization yields $d^6 + d^6L^2$ in the Cr-doped system, highlighting metal-ligand hybridization as a route to tune
magnetic, electronic and orbitronic properties.
Read the full abstract ▾
Materials Science
Zirconium Carbide as a High-Temperature Benchmark for the Beyond Quasi-Harmonic Method
Christopher M. Stanley
Molar heat capacity at constant pressure, C_p (T), is a central thermodynamic quantity in materials science, but it remains difficult to calculate accurately from first principles when anharmonic vibrational effects become important. In this work, rocksalt ZrC is used as a high-temperature
benchmark for the Beyond Quasi-Harmonic (BQH) method, a prepared-supercell first-principles approach that extracts anharmonic vibrational energy directly from density-functional-theory energy evaluations. The calculated BQH molar heat capacity is compared with CALPHAD reference values, a fully anharmonic thermodynamic-integration calculation, a calculated C_v (T) curve from the present work, and a quasi-harmonic calculation. The BQH curve gives a substantial improvement beyond C_v (T) and beyond the quasi-harmonic approximation. Because ZrC is electronically conductive, an electronic heat-capacity correction was also estimated from the density of states at the Fermi level and added to the vibrational BQH result. This correction brings the calculated molar heat capacity into close agreement with the fully anharmonic theoretical
benchmark through approximately 1200 K. These results show that the BQH method fully captures important anharmonic
phonon contributions missing from ordinary quasi-harmonic calculations.
Read the full abstract ▾
Materials Science · Cross-listed from physics.app-ph
Dynamic Sensing via Photomodulated Gas Desorption in Plasmonic Nanoparticle Chemiresistors
Lukas Mielke, Dahee Heo, Gabriele Carelli et al. (+1 more)
Quasi-static sensing, i.e., measurement of a sensor signal change induced by analyte presence with respect to a baseline signal observed in a reference gas beforehand, is the state of the art for qualitative and quantitative analyte identification in chemiresistive sensing. However, this approach is prone to baseline drift and, especially for inexpensive miniaturized point-of-care sensors, repeated calibration with reference gas is not feasible. To access reliable baseline information, active switching between analyte and reference gas would be required, causing a limitation for miniaturized implementation. Dynamic excitation of sensors offers an alternative: Via external stimuli the sensor is reversibly driven out of
equilibrium in a controlled way, and the resulting transient sensor response, which is dependent on analytes present, is recorded and interpreted. Correlation of excitation and response signals can reduce effects of baseline drift and furthermore, dynamic features in sensor responses may contain valuable information. Especially light activation is a powerful and potentially miniaturizable approach to agitate sorption processes and therefore induce dynamics. In this work we report photothermal heating of hybrid, chemiresistive gold nanoparticle composites via LED excitation matching the plasmon resonance, to dynamically shift the analyte sorption
equilibrium and induce dynamic sensor responses in a highly controlled way. We demonstrate that these sensor responses enable the detection of volatile organic compounds (VOC) via interpretation of differential signal components and that this approach improves the chemiresistors' baseline stability.
Read the full abstract ▾
All authors Lukas Mielke, Dahee Heo, Gabriele Carelli, Hendrik Schlicke
Materials Science
Controlling Hydrogen Isotope Retention at Helium Cavities through Radiation-Induced Segregation in Fusion Steels
Lihao Shi, Logan N. Clowers, Qing Peng et al. (+2 more)
Hydrogen isotope retention in
plasma facing and structural
alloys is a central materials challenge for deuterium-tritium fusion. Motivated by ion beam irradiation experiments and first principles calculations, we identify an irradiation-enabled mechanism whereby solute segregation to defect sinks enhances hydrogen isotope trapping. Triple-ion irradiation of reduced activation ferritic-martensitic steel F82H reveals pronounced segregation of Cr and Ta to cavity surfaces. Density functional theory shows that these segregants markedly increase H stability at cavities by strengthening binding energies and increasing migration barriers, leading to substantially higher
attention. The effect originates from solute-tuned electronic structure: Ta promotes strong H 1s-metal d orbital hybridization, whereas Cr shifts the surface d-band toward a more favorable bonding configuration. These findings provide an atomistic link between irradiation-induced segregation and elevated-temperature hydrogen isotope retention and
alloy chemistry routes to control tritium inventory in fusion environments.
Read the full abstract ▾
All authors Lihao Shi, Logan N. Clowers, Qing Peng, Gary S. Was, Fei Gao
Statistical Mechanics
Stochastic Processes as Non-Metric Geodesics in Information Geometry
T. Koide and A. van de Venn
We establish a one-to-one correspondence between geodesics associated with the one-parameter family of $\alpha$-connections on the Gaussian statistical
manifold and a class of continuous
stochastic processes characterized by a time-independent noise intensity. We demonstrate that geodesics in expectation parameters naturally classify into three distinct
geometric categories, among which the Boundary-connecting class allows us to construct an explicit linear
stochastic realization with constant
diffusion, representing a generalized bridge process. This result demonstrates how continuous
stochastic processes within this Gaussian class can be extended along
geometric curves. Under appropriate operational limits, this generalized bridge process reduces to fundamental
stochastic dynamics, either Ornstein-Uhlenbeck (OU) relaxation or free Brownian
diffusion. Crucially, the physical restoring force governing the resulting OU relaxation directly determines the underlying connection parameter $\alpha$, providing a concrete physical observable to constrain the
manifold geometry. Depending on the chosen affine connection representation, this restoring force can be attributed either to scalar
curvature or purely to non-metricity, establishing a direct conceptual analogy with the Geometrical Trinity of
Gravity. Furthermore, applying this framework to driven
stochastic thermodynamics, we show that the work-minimizing optimal protocol in the slow-driving limit coincides precisely with an expectation geodesic of the statistical
manifold with non-metricity equipped with $(g, {}^{(1/2)}\Gamma, {}^{(-1/2)}\Gamma)$, highlighting the active physical role of non-metricity in information geometry.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Non-perturbative theory of valley splitting in Si qubits from variational wave function: periodic effects of shear strain and asymptotic freedom in the wiggle-well potential
Johannes L. P. Steinschuld, Hendrik J. Bluhm and Seyed Akbar Jafari
Valley splitting sets the energy scale at which
spin and valley degrees of freedom hybridize in silicon
quantum-well
qubits, but its sensitivity to interface structure makes it difficult to predict. Using the valleyor basis, we formulate a two-band effective-mass model for intervalley coupling in a finite
quantum well and develop an analytical framework for treating non-perturbative effects of shear strain and wiggle-well potentials. For a $z$-independent coupling $V_s\tau_2$, corresponding to uniform shear strain, we construct a variational state from the exact plane-wave valleyors and a hard-wall envelope. This yields closed-form expressions for the two lowest states and their splitting, including the characteristic oscillatory $|\sin(k_{\rm min}L)|$ dependence. The variational result agrees with exact diagonalization to within $\sim1\%$ for realistic couplings, and provides a simple prescription for tuning the shear strain away from the nodes to enhance the valley splitting. We further show that finite barrier heights primarily renormalize the effective width of the
quantum well while preserving the oscillatory dependence. For a wiggle-well coupling $V_w\cos(k_wz)\tau_1$, the valleyor representation reveals a crossover near the $k_w=2k_1$ resonance from wiggle-dominated splitting to orbital quantization. Remarkably, at high wiggle-well amplitudes, the empty-box energy scale predominantly dictates the near-resonant valley splitting, while the wiggle-well potential enters only as a sub-leading correction. This behavior can be viewed as asymptotic freedom for
spin qubits. Away from resonance, the splitting exhibits a broadly peaked resonance with diffraction-like side-lobes as a function of detuning.
Read the full abstract ▾
Statistical Mechanics · Cross-listed from physics.ed-ph
From Local Context to Climate Science: Low-Cost Experimentation in the Initial Training of Physics Teachers
André A. A. Marinho, Edson R. L. Lopes, Jhon KF V. Silva et al. (+2 more)
Climate change poses a major scientific, environmental, and educational challenge, requiring approaches that connect physical concepts, empirical evidence, and socially relevant environmental issues. This study presents and analyzes a low-cost experimental investigation developed within the "Physics and the Environment" course of a Physics teacher training program at the State University of the Tocantina Region of Maranhão (UEMASUL), Brazil. The experiment involved constructing a simplified thermal simulator using accessible materials and comparing a confined system with an open control system, both exposed simultaneously to solar radiation. The results showed that the average temperature inside the simulator was $45.91^{\circ}\mathrm{C}$, compared to $38.58^{\circ}\mathrm{C}$ in the external control system, corresponding to a mean temperature difference of $7.33^{\circ}\mathrm{C}$ (among other analyses). These results demonstrate that the experimental setup was capable of producing and measuring a significant thermal difference between the two systems. However, the observed temperature rise should not be interpreted as a direct measure of the atmospheric greenhouse effect, given that the experimental apparatus involves both radiative and non-radiative heat transfer mechanisms. The study emphasizes the educational potential of low-cost experimentation as a strategy to integrate electromagnetic radiation, energy balance, temperature, heat transfer, and
climate science into the initial training of physics teachers. It also highlights the importance of explicitly discussing the limitations of experimental models and distinguishing local experimental evidence from conclusions regarding global
climate processes.
Read the full abstract ▾
All authors André A. A. Marinho, Edson R. L. Lopes, Jhon KF V. Silva, Mariana S. Costa, Maria A. Morais
Statistical Mechanics
When does nonreciprocity matter? Scale-dependence and nonequilibrium signatures
Sarah A.M. Loos and Robert L. Jack
Nonreciprocity is increasingly recognized as a unifying concept linking diverse nonequilibrium phenomena found across physics, chemistry, and biology. It gives rise to distinctive behavior including run-and-chase dynamics and spatio-temporal patterns, often associated with a breaking of time-reversal
symmetry. However, nonreciprocity and its nonequilibrium signatures are fundamentally scale-dependent, and may emerge or disappear under coarse-graining. A central challenge is therefore to understand when and how nonreciprocity manifests itself on different scales, for example via irreversible fluctuations or macroscopic currents. In this Perspective, we discuss the physical origin and fate of effective nonreciprocal interactions and the characteristic irreversible dynamics they give rise to across scales.
Read the full abstract ▾
Materials Science
Contrasting roles of the superexchange and direct exchange interactions in the metal-insulator transitions of the 2D ferromagnetic $1T$-Fe$X_2$ ($X$=Cl, Br, I) monolayers
Hongxu Luo, Baoyang Zhou and Sai Lyu
Within the rapidly growing family of two-dimensional (2D) materials, 2D ferromagnetic (FM) materials have attracted a great deal of recent
attention. The ferromagnetism in 2D FM materials originates from the underlying exchange interactions. In particular, metal-
insulator transitions (MITs) in 2D FM materials induced via various modulation strategies is critical to the design of 2D electronic devices with reduced sizes (e.g. transistor). However, the critical behaviors of exchange interactions and their effects on the Curie temperatures near MITs remains to be clarified. By taking the 2D FM 1T-FeX2 (X=Cl, Br, I) monolayers as the testbeds, we computationally study the critical behaviors of the exchange interactions in the vicinity of the MITs driven by the on-site Coulomb electron-electon interactions. The FM superexchange interactions and the direct exchange interactions are found to energetically favor the halfmetallic and semiconducting states, respectively. In addition, the halfmetallic states have the stronger FM couplings and thus the higher Curie temperatures. This study provides a comprehensive understanding of the interrelations between MITs and exchange interactions and could be useful for the device design requiring both MITs and exchange-interaction related
magnetic properties, particularly robust
magnetic ordering and higher Curie temperatures, in 2D FM materials.
Read the full abstract ▾
Soft Condensed Matter · Cross-listed from physics.comp-ph
Structure-Informed Bayesian Inference of Anomalous Transport and Hidden Molecular Trapping in Amorphous Media
Andrey Ananev, Maria Potapova, Nikolay Kondratyuk et al. (+2 more)
Molecular
diffusion in fluctuating amorphous and macromolecular media governs key transport processes across soft-matter physics, energy storage, and biological membranes. Extracting localized trapping states from single-particle tracking trajectories remains a fundamental challenge; because thermal structural breathing continuously reconfigures pore boundaries, conventional
geometric algorithms suffer from severe systematic biases, erroneously merging distinct localized states during cyclic molecular returns. Here, we address this deadlock by shifting the paradigm from local
geometric recurrence to a structure-informed
Bayesian regularization. Leveraging discrete Morse theory, we extract the time-invariant topological skeleton of the fluctuating host
matrix to construct robust, gas-specific physical priors that account for individual molecular dimensions. Trajectory steps are sequentially partitioned via a two-stage probabilistic refinement that dynamically adapts to the transport landscape. Benchmarked against a rigorous environment where synthetic particles explore the actual interconnected
matrix graph, our approach eliminates systemic biases, restricting macroscopic trapping parameter deviations to just a few percent under optimal linear $O(N)$ computational scaling. Applied to hydrogen and methane transport within a type-I kerogen
matrix, serving as a prototype for highly tortuous, flexible macromolecular networks, the method successfully decodes the hidden microscopic mechanisms of confined
diffusion. To ensure immediate broad impact, the documented open-source code and data are made publicly available, offering an accessible strategy readily adaptable to a broad spectrum of tracking phenomena, from ion transport in battery
polymers to
protein trafficking within cellular environments.
Read the full abstract ▾
All authors Andrey Ananev, Maria Potapova, Nikolay Kondratyuk, Timur Vostroknutov, Aleksey Khlyupin
Strongly Correlated Electrons
Examining Convergence of Cluster Perturbation Theory and Cluster Coupled Cluster for J1-J2 Heisenberg Spin Lattices
Jeffrey Keyes and Carlos Jimenez-Hoyos
In previous work, it was shown that using the cluster mean field(cMF) wavefunction as the zeroth order wavefunction for perturbation theory and coupled cluster produces a reasonable approximation for the J 1-J 2 Heisenberg model in the thermodynamic limit(TDL). However, this work was limited to cPT4 and cCCSD. The central claim of cMF is that it takes strongly correlated systems and makes them weakly correlated so that PT weakly correlated methods can be used. To confirm that this claim is true, it is important to show that the PT and CC series converge. In this paper, we extend the previous calculations to cPT7 and cCCSDTQ5 where we show that the energy is converging. We also discuss how to perform cluster based calculations efficiently in the thermodynamic limit, which is crucial for these more expensive calculations.
Read the full abstract ▾
Mesoscale and Nanoscale Physics
Decorated electronic kagome lattice in twisted bilayer germanene
Dennis J. Klaassen, Rian A.M. Ligthart, Andrés R. Botello Mendez et al. (+10 more)
Artificial kagome
lattices provide a route to electronic flat bands,
geometric frustration, and correlation driven phases, but their realization in atomically controlled two-dimensional materials remains scarce. Here, we show that commensurate twisted bilayer germanene on Ge2Pt produces two electronically distinct large-angle moiré phases. Scanning tunneling microscopy measurements and density functional theory calculations reveal that commensurate twisted bilayers that are odd under an exchange of sublattices are semiconducting, whereas the twisted bilayers with an even parity are metallic. The twisted bilayers with an even parity host an empty state resonance that exhibits an emergent decorated kagome structure with a C3
symmetry. These results establish large-angle twisted germanene as a platform for engineering kagome-like electronic states in a buckled two-dimensional material.
Read the full abstract ▾
All authors Dennis J. Klaassen, Rian A.M. Ligthart, Andrés R. Botello Mendez, Lumen Eek, Esra van 't Westende, Paul L. de Boeij, Y. Wang, D. Vanmaekelbergh, Pantelis Bampoulis, Cristiane Morais Smith, Ingmar Swart, Zeila Zanolli, Harold J.W. Zandvliet
Materials Science
The absence of a central metal ion destabilizes phthalocyanine on In$_2$O$_3$(111)
Viktoria Waidbacher, Sarah Tobisch, Faith J. Lewis et al. (+5 more)
Metal phthalocyanines (MPc) are a versatile molecular platform for applications ranging from organic optoelectronic devices to single-atom catalysis (SAC). Their adsorption and layer formation on the prototypical transparent electrode substrates of organic optoelectronic devices is directly relevant for charge injection and transport across the organic-oxide interface. Moreover, the well-defined M-N$_4$ coordination of the metal cation defines their activity as SACs for (electro-)catalysis. Here, the adsorption of the metal-free phthalocyanine (H$_2$Pc) is characterized on In$_2$O$_3$(111) using low-temperature STM, nc-AFM, and STS. In$_2$O$_3$ is not only a model system of indium tin oxide (ITO) but also an active catalytic material for CO$_2$ reduction. H$_2$Pc adsorbs in the same site and configuration reported for copper phthalocyanine [J. Mater. Chem. C 13, 17650-17661 (2025)] and for the majority of cobalt phthalocyanine [Surf. Sci. 722, 122065 (2022)]. Despite this shared preference in adsorption site, H$_2$Pc cannot be organized into extended and ordered monolayer structures by gentle annealing: the molecule starts to decompose at $\approx$50$^\circ$C, well below the temperature used to grow monolayers of CoPc and CuPc. Self-metalation is not observed on stoichiometric In$_2$O$_3$(111). On the reduced surface where In$^0$ adatoms are present, new H$_2$Pc-related features appear but cannot be identified by imaging only. The comparison of H$_2$Pc with CoPc and CuPc identifies distinct roles of the central metal ion in the metal-Pc/In$_2$O$_3$(111) systems: it acts as a structural anchor that stabilizes the macrocycle against decomposition on the surface, and it modifies the frontier-orbital character in ways that determine whether a second adsorption configuration is populated.
Read the full abstract ▾
All authors Viktoria Waidbacher, Sarah Tobisch, Faith J. Lewis, Moritz Eder, Michael Schmid, Gareth Parkinson, Ulrike Diebold, Margareta Wagner
Materials Science
Study on Thickness and Temperature Dependence of Thermoelectric Properties in SnS Nanofilms
Liqi Chen, Ziyang Wang, Donghao Li et al. (+5 more)
SnS as an environmentally friendly, cost-effective, and earth-abundant narrow-bandgap
semiconductor material, has demonstrated significant application potential in the field of medium-temperature thermoelectric conversion. However, the thermoelectric performance of its bulk counterpart is inherently constrained by intrinsic point defects (e.g., vacancies) and the material's specific band structure. Low-dimensional engineering has emerged as a pivotal strategy for overcoming these limitations and enhancing thermoelectric performance. In this work, we systematically investigate the thermoelectric properties of SnS nanofilms with distinct thicknesses (82 nm, 199 nm, 616 nm, and 813 nm) across a temperature range of 300-600 K. Measurements were conducted using time-domain thermoreflectance (TDTR) and a dedicated thin-film thermoelectric parameter test system (ZEM-3). Our results confirm that low-dimensionalization effectively boosts the thermoelectric performance of SnS, with the thermoelectric figure of merit (ZT) displaying a pronounced dependence on both film thickness and temperature. All four SnS thin films exhibit thermoelectric performance that is markedly superior to that of bulk SnS. This enhancement is primarily attributed to the
quantum confinement effect, energy filtering effect, and intensified
phonon scattering, all of which are induced by the low-dimensional structural characteristics. This work provides not only experimental evidence and theoretical insights for the performance optimization of SnS nanofilms but also establishes a foundational framework for the development of high-efficiency, eco-friendly medium-temperature thermoelectric materials, thereby holding significant scientific value and practical implications.
Read the full abstract ▾
All authors Liqi Chen, Ziyang Wang, Donghao Li, Jingye Wang, Ning Zhao, Jun Zhou, Jie Zhu, Dawei Tang
Materials Science
Pressure Dependence of Ferromagnetism in Uranium Hydride UH$_3$ up to 20 GPa Revealed by NV Centers Magnetometry
Valentin Schmidt, Loïc Toraille, Florent Occelli et al. (+2 more)
The origin of ferromagnetism in the stable $\beta$-UH$_3$ phase is still debated. With a high Curie temperature and a short uranium-uranium interatomic distance, $\beta$-UH$_3$ is placed outside the known systematics of uranium compounds. Pressure provides a powerful means of tuning magnetism toward its suppression, thereby offering valuable insights into its underlying mechanisms, yet the high-pressure behavior of $\beta$-UH$_3$ has remained largely unexplored. Here, we combine in the Diamond Anvil
Cell (DAC) the development of pure $\beta$-UH$_3$ synthesis and widefield nitrogen-vacancy (NV) center magnetometry to measure the pressure dependence of the Curie temperature in $\beta$-UH$_3$ up to about 20~GPa. We present two data analysis methods, vector
magnetic field reconstruction and statistical analysis of the optically detected
magnetic resonance (ODMR) response, which enable us to directly image the
magnetic dipole of $\beta$-UH$_3$ during isobaric warming. We observe a linear decrease in the Curie temperature with pressure, yielding a slope of $\text{d}T_C/\text{d}P=-3.86\,(8)$~K/GPa. Ferromagnetism in $\beta$-UH$_3$ is predicted to reach 0~K at approximately 44~GPa, where a
quantum critical point may emerge.
Read the full abstract ▾
All authors Valentin Schmidt, Loïc Toraille, Florent Occelli, Jean-François Roch, Paul Loubeyre
Soft Condensed Matter
Effective particle size governs structure and dynamics in rough hard-particle fluids
Nanqing Xiao, Zhen Zhang, Walter Kob et al. (+1 more)
We numerically investigate how particle surface roughness affects the static and dynamic properties of a hard-particle fluid across a wide range of densities, rho. These simulations of a simple model of granular systems reveal that, although the amplitude and coverage of surface corrugation significantly influence the rho-dependence of system properties, the qualitative behavior of this dependence remains unchanged. These findings can be described quantitatively by introducing an effective particle size, which enables a direct mapping of the rough particle systems to equivalent hard-disk systems. Analytical calculations provide an explicit form of this mapping, and allow us to predict the static and dynamic properties of rough particles using standard
liquid-state theories for hard disks.
Read the full abstract ▾
All authors Nanqing Xiao, Zhen Zhang, Walter Kob, Yujie Wang
Strongly Correlated Electrons
$g$-wave altermagnetic order parameter in hematite
Tianren Wang, Yuehong Li, Yu Feng et al. (+11 more)
Altermagnets combine the vanishing net magnetization of antiferromagnets with momentum-dependent
spin splitting.
Magnon band splitting provides a direct probe of altermagnetic order and may enable chirality-selective
magnon transport, yet the momentum-space
symmetry of this splitting has not been determined quantitatively. Here we use inelastic
neutron scattering to map the momentum dependence of altermagnetic
magnon splitting in hematite ($\alpha$-Fe$_2$O$_3$). The splitting vanishes along nodal directions and reaches maxima off the nodes, revealing the $g$-wave
symmetry of the altermagnetic order parameter. These results agree with linear
spin-wave theory calculations based on the altermagnetic model, which further identify the nondegenerate branches as
magnons of opposite chirality and trace the splitting to
symmetry-inequivalent long-range exchange interactions. Our results provide the first quantitative determination of the momentum-space
symmetry of altermagnetic chiral
magnons. These findings, together with hematite's high
magnetic ordering temperature and low
magnon damping, establish it as a promising platform for low-dissipation,
symmetry-selective magnonic applications.
Read the full abstract ▾
All authors Tianren Wang, Yuehong Li, Yu Feng, Andong Liu, Yuetong Wu, Qian Zhao, Yujie Yan, Wei Luo, Xin Tong, Yi Lu, Yao Shen, Stefano Agrestini, Jaewon Choi, Qisi Wang
Mesoscale and Nanoscale Physics
Observation of linear magnetoresistance and planar Hall effect in the Dirac semimetal PdTe
Bhawana Mehra, Bibek Ranjan Satapathy, V S Abhishek et al. (+5 more)
PdTe is a Dirac semimetal that also exhibits superconductivity, providing an intriguing platform to explore topological superconductivity and unconventional magnetotransport phenomena. While the superconducting properties of PdTe have been extensively studied in recent years, the detailed magnetotransport phenomena have remained unexplored. Here, we present the first observation of linear magnetoresistance (LMR) and the planar Hall effect (PHE) in a high-quality single
crystal of PdTe. We observe temperature-dependent unsaturated LMR in both in-plane ($B \parallel I$) and out-of-plane ($B \perp I$) configurations. The magnetoresistance (MR) shows a crossover from parabolic to linear dependence at the critical field Bc, and detailed analysis indicates that disorder-driven mobility fluctuations are the origin rather than the Abrikosov
quantum-limit mechanism. Furthermore, prominent PHE has been observed by rotating the
magnetic field within the plane of the sample. The detailed analysis of the field and temperature dependence of PHE-amplitude, along with the parametric plot, suggests that PHE originates predominantly from the anisotropic orbital magnetoresistance rather than the chiral anomaly. Our results demonstrate that although the Dirac point is close to the Fermi level, the observed LMR and PHE in the Dirac semimetal PdTe can be understood within a semiclassical transport framework, highlighting the importance of distinguishing between topological and conventional classical transport mechanisms in topological materials
Read the full abstract ▾
All authors Bhawana Mehra, Bibek Ranjan Satapathy, V S Abhishek, Reena, Ritu Gupta, Yogesh Singh, S. Chakraverty, Amit Vashist
Mesoscale and Nanoscale Physics
Wafer-Level 1/f Noise Characterization of Scaled P-Type Nanosheets and Comparison with Planar HKMG Transistors
Ruben Asanovski, Anabela Veloso, Ben Kaczer et al. (+2 more)
We present a comprehensive wafer-level 1/f noise study of scaled Gate-All-Around (GAA) p-type nanosheet transistors and
benchmark them against large-area planar High- ąppa} Metal Gate (HKMG) devices to assess the impact of device architecture on reliability. By statistically analyzing noise data from 188 nanosheets, we extract the effective trap density in the dielectric and compare it to that of planar transistors with identical gate stack, comparable processing thermal budgets, and no specific reliability anneals. The effective trap density extracted from 1/f noise is comparable in planar and nanosheet architectures. This indicates that transitioning to GAA nanosheets does not increase noise, which remains governed by gate stack quality.
Read the full abstract ▾
All authors Ruben Asanovski, Anabela Veloso, Ben Kaczer, Naoto Horiguchi, Jacopo Franco
Quantum Gases
Exciton-polariton condensates in epsilon-near-zero cavities
Ege Özgün
We propose an epsilon-near-zero (ENZ) artificial cavity that can enhance light-matter coupling around the ENZ frequency and theoretically show the possibility of
exciton-polariton condensation in the suggested platform. By using a rate equation model based on the driven-dissipative reservoir approach, we calculate the pump threshold for condensation and then compare the suggested platform's advantages/disadvantages with distributed Bragg reflector cavities. We also discuss the validity of the mean field theory within our model.
Read the full abstract ▾
Materials Science
Pulse-Burst Excitation Reveals Time-Dose Reciprocity Breakdown in Mixed-Halide Perovskites
Alexandr Marunchenko, Shivam Singh, Daniel Lizotte et al. (+3 more)
Time-dose reciprocity, commonly associated with the Bunsen-Roscoe law, states that the response of a photosensitive system depends only on the total exposure dose, regardless of how that energy is delivered over time. Light-sensitive processes in mixed-halide perovskites, such as photoinduced halide segregation, often exhibit threshold-like behavior that may violate this principle and enable material-state control by
photon timing. We test this using pulse-burst excitation, which introduces an additional temporal control dimension beyond conventional parameters such as pulse fluence, repetition rate, and average power. By redistributing the same
photon dose over microsecond-to-millisecond timescales, we create distinct nonequilibrium excitation conditions and show that mixed-halide perovskites can evolve into different metastable states, revealing a breakdown of time-dose reciprocity in the combined processes of halide segregation and remixing. This additional temporal degree of freedom not only enables control of the material state but also provides a new experimental framework for disentangling the competing processes underlying photoinduced halide redistribution. Our findings establish
photon timing as a control parameter for perovskite photochemistry and open additional opportunities for optical
memory and neuromorphic photonic applications.
Read the full abstract ▾
All authors Alexandr Marunchenko, Shivam Singh, Daniel Lizotte, Bhaskar De, Yana Vaynzof, Ivan G. Scheblykin
Materials Science
Polymorph Engineering of the Layered Rare-Earth Magnet GdAlGe
Dmitry V. Averyanov, Ivan S. Sokolov, Alexander N. Taldenkov et al. (+7 more)
The recent advances in research on layered magnets have established them as invaluable materials for spintronic applications and precursors to 2D magnets. The problem is that the number of such materials available for experimentation is still low. To tackle the problem, one may employ phase engineering; in particular, the interplay between the phase stability and dimensionality provides great opportunities for design of layered magnets. Here, this interrelation is harnessed to produce epitaxial films of an overlooked layered polymorph of GdAlGe. The compound is formed by alternating triangular Gd and honeycomb AlGe
lattices. It is stable in ultrathin films, up to 5 monolayers. In thicker films, an additional unwanted phase emerges. The structural quality of the ultrathin films is witnessed by electron and X-ray diffraction as well as electron microscopy. Magnetization measurements detect an anisotropic ferromagnetic state. The GdAlGe magnetism is corroborated by a study of electron transport revealing the anomalous Hall effect and negative magnetoresistance. The material is naturally integrated with Ge, a technological
semiconductor, which should facilitate applications. The present study can serve as a blueprint for design of layered magnets via polymorph engineering.
Read the full abstract ▾
All authors Dmitry V. Averyanov, Ivan S. Sokolov, Alexander N. Taldenkov, Oleg E. Parfenov, Alexey N. Mihalyuk, Ivan A. Yakovlev, Igor A. Karateev, Oleg A. Kondratev, Andrey M. Tokmachev, Vyacheslav G. Storchak