CMP Journal 2025-01-28
Statistics
Nature Physics: 1
Physical Review Letters: 4
arXiv: 104
Nature Physics
The formation of a nuclear-spin dark state in silicon
Original Paper | Electronic properties and materials | 2025-01-27 19:00 EST
Xinxin Cai, Habitamu Y. Walelign, John M. Nichol
Silicon-based qubits are often made by trapping individual electrons in quantum dots defined by electric gates. Quantum information can then be stored using the spin states of the electrons. However, the nuclei of the surrounding atoms also have spin degrees of freedom that couple to the electron-spin qubits and cause decoherence. The emergence of a nuclear-spin dark state has been predicted to reduce this coupling during dynamic nuclear polarization, when the electrons in the quantum dot drive the nuclei in the semiconductor into a decoupled state. Here we report the formation of a nuclear-spin dark state in a gate-defined silicon double quantum dot. We show that, as expected, the transverse electron-nuclear coupling rapidly diminishes in the dark state, and that this state depends on the synchronized precession of the nuclear spins. Moreover, the dark state significantly reduces the relaxation rate between the singlet and triplet electronic spin states. This nuclear-spin dark state has potential applications as a quantum memory or in quantum sensing, and might enable increased polarization of nuclear-spin ensembles.
Electronic properties and materials, Quantum information
Physical Review Letters
Certifying Quantum Temporal Correlation via Randomized Measurements: Theory and Experiment
Research article | Quantum correlations in quantum information | 2025-01-28 05:00 EST
Hongfeng Liu, Zhenhuan Liu, Shu Chen, Xinfang Nie, Xiangjing Liu, and Dawei Lu
We consider the certification of temporal quantum correlations using the pseudo-density operator (PDO), an extension of the density matrix to the time domain, where negative eigenvalues are key indicators of temporal correlations. Conventional methods for detecting these correlations rely on PDO tomography, which often involves excessive redundant information and requires exponential resources. In this work, we develop an efficient protocol for temporal correlation detection by virtually preparing the PDO within a single time slice and estimating its second-order moments using randomized measurements. Through sample complexity analysis, we demonstrate that our protocol requires only a constant number of measurement bases, making it particularly advantageous for systems utilizing ensemble average measurements, as it maintains constant runtime complexity regardless of the number of qubits. We experimentally validate our protocol on a nuclear magnetic resonance platform, a typical thermodynamic quantum system, where the experimental results closely align with theoretical predictions, confirming the effectiveness of our protocol.
Phys. Rev. Lett. 134, 040201 (2025)
Quantum correlations in quantum information, Quantum correlations, foundations & formalism, Quantum simulation
Ultraviolet-Complete Local Field Theory of Persistent Symmetry Breaking in \(2+1\) Dimensions
Research article | Finite temperature field theory | 2025-01-28 05:00 EST
Bilal Hawashin, Junchen Rong, and Michael M. Scherer
A local quantum field theory is found to spontaneously break a global symmetry at all temperatures, defying the normal expectation that symmetries get restored at high temperatures.
Phys. Rev. Lett. 134, 041602 (2025)
Finite temperature field theory, Nonperturbative effects in field theory, Quantum field theory, Renormalization group, Spontaneous symmetry breaking
Importance of Density for Phase-Change Materials Demonstrated by Ab Initio Simulations of Amorphous Antimony
Research article | Density of states | 2025-01-28 05:00 EST
Nils Holle, Sebastian Walfort, Jakob Ballmaier, Riccardo Mazzarello, and Martin Salinga
Phase change materials (PCMs) serve as useful components in electronics and photonics. Here we demonstrate that various kinds of material properties of a PCM are significantly influenced by the realized mass density. Using ab initio simulations, we investigate supercooled-liquid antimony and the subsequent transition to a glassy phase. We observe a transition in the supercooled-liquid phase from an undistorted high-temperature to an increasingly Peierls-like distorted low-temperature phase. This transition also manifests in both the electronic density of states and optical properties. The strong dependence of these properties on mass density leads the way to explorations of property design for nanoconfined devices beyond the usual compositional modifications.
Phys. Rev. Lett. 134, 046101 (2025)
Density of states, Glass transition, Liquid-liquid phase transition, Optical & microwave phenomena, Peierls transition, Phase-change materials, Electronic structure, Elemental materials, Glasses, Memristors, Semimetals, Density functional theory, Molecular dynamics
Constant-Potential Modeling of Electrical Double Layers Accounting for Electron Spillover
Research article | Batteries | 2025-01-28 05:00 EST
Zhenxiang Wang, Ming Chen, Jiedu Wu, Xiangyu Ji, Liang Zeng, Jiaxing Peng, Jiawei Yan, Alexei A. Kornyshev, Bingwei Mao, and Guang Feng
Constant-potential molecular dynamics (MD) simulations are indispensable for understanding the structure, capacitance, and dynamics of electrical double layers (EDLs) at the atomistic level. However, the classical constant-potential method, relying on the so-called ''fluctuating charges'' to keep electrode equipotential, overlooks quantum effects on the electrode and always underestimates EDL capacitance for typical metal electrode and aqueous electrolyte interfaces. Here, we propose a constant potential method accounting for electron spillover on the outermost nuclei of the electrode. For EDLs at Au(111) electrodes, our MD simulation reveals bell-shaped capacitance curves in magnitude and shape both quantitatively consistent with experiments. It unveils the electrode-polarization-dependent local electric fields, agreeing with experimental observations of redshift vibration of interfacial water under negative polarization and predicting a blueshift under positive polarization, and further identifies geometry dependence of two timescales during charging.
Phys. Rev. Lett. 134, 046201 (2025)
Batteries, Capacitance, Charge, Electric polarization, Electronic structure, Supercapacitors, Liquid-solid interfaces, Molecular dynamics, Multiscale modeling
arXiv
Study on the SDW and Superconductivity in La\(_3\)Ni\(_2\)O\(_{7}\) at ambient pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Yu-Bo Liu, Hongyi Sun, Ming Zhang, Qihang Liu, Wei-Qiang Chen, Fan Yang
The discovery of high-temperature superconductivity (SC) with \(T_c\approx 80\) K in the pressurized La\(_3\)Ni\(_2\)O\(_{7}\) has aroused great interests. Currently, due to technical difficulties, most experiments on La\(_3\)Ni\(_2\)O\(_{7}\) can only be performed at ambient pressure (AP). Particularly, various experiments have revealed the presence of spin-density wave (SDW) in the unidirectional diagonal double-stripe pattern with wave vector near \((\pi/2,\pi/2)\) in La\(_3\)Ni\(_2\)O\(_{7}\) at AP. In this work, we employ first-principle calculations followed by the random phase approximation (RPA)-based study to clarify the origin of this special SDW pattern and potential SC in La\(_3\)Ni\(_2\)O\(_{7}\) at AP. Starting from our density-functional-theory (DFT) band structure, we construct an eight-band bilayer tight-binding model using the Ni-\(3d_{z^2}\) and \(3d_{x^2-y^2}\) orbitals, which is equipped with the standard multi-orbital Hubbard interaction. Our RPA calculation reveals an SDW order driven by Fermi-surface nesting with wave vector \(Q\approx(0,0.84\pi)\) in the folded Brillouin zone (BZ). From view in the unfolded BZ, the wave vector turns to \(Q_0\approx(0.42\pi,0.42\pi)\), which is near the one detected by various experiments. Further more, this SDW exhibits an interlayer antiferromagnetic order with a unidirectional diagonal double-stripe pattern, consistent with recent soft X-ray scattering experiment. This result suggests that the origin of the SDW order in La\(_3\)Ni\(_2\)O\(_{7}\) at AP can be well understood in the itinerant picture as driven by FS-nesting. In the aspect of SC, our RPA study yields an approximate \(s^\pm\)-wave spin-singlet pairing with \(T_c\) considerably lower than that under high pressure, which is consistent with experiments. Furthermore, the \(T_c\) can be strongly enhanced through hole doping, leading to possible high-temperature SC in the material.
Superconductivity (cond-mat.supr-con)
12 pages, 5 figures
Atypical vortex lattice and the magnetic penetration depth in superconducting Sr\(_2\)RuO\(_4\) deduced by \(\mu\)SR
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
M. Yakovlev, Z. Kartsonas, J. E. Sonier
The muon spin rotation (\(\mu\)SR) technique has been applied to determine the behavior of the in-plane magnetic penetration depth (\(\lambda_{ab}\)) in the vortex state of the unconventional superconductor Sr\(_2\)RuO\(_4\) as a means of gaining insight into its still unknown superconducting order parameter. A recent \(\mu\)SR study of Sr\(_2\)RuO\(_4\) reported a \(T\)-linear temperature dependence for \(\lambda_{ab}\) at low temperatures that was not identified in an earlier \(\mu\)SR study. Here we show that there is no significant difference between the data in the early and recent \(\mu\)SR studies and both are compatible with the limiting low-temperature \(\lambda_{ab} \sim T^2\) dependence expected from measurements of the change in \(\lambda_{ab}(T)\) in the Meissner state by other techniques. However, we argue that at this time there is no valid theoretical model for reliably determining the absolute value of \(\lambda_{ab}\) in Sr\(_2\)RuO\(_4\) from \(\mu\)SR measurements. Instead, we identify the formation of an unusual square vortex lattice that introduces a new constraint on candidate superconducting order parameters for Sr\(_2\)RuO\(_4\).
Superconductivity (cond-mat.supr-con)
6 pages, 3 figures
Two-body contact of a Bose gas near the superfluid--Mott-insulator transition
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Moksh Bhateja, Nicolas Dupuis, Adam Rançon
The two-body contact is a fundamental quantity of a dilute Bose gas
which relates the thermodynamics to the short-distance two-body
correlations. For a Bose gas in an optical lattice, near the
superfluid--Mott-insulator transition, a
universal'' contact $C_{\rm univ}$ can be defined from the singular part $P-P_{\rm MI}$ of the pressure ($P_{\rm MI}$ is the pressure of the Mott insulator). Its expression $C_{\rm univ}=C_{\rm DBG}(|n-n_{\rm MI}|,a^\ast)$ coincides with that of a dilute Bose gas provided we consider the effectivescattering
length'' \(a^\ast\) of the
quasi-particles at the quantum critical point (QCP) rather than the
scattering length in vacuum, and the excess density \(|n-n_{\rm MI}|\) of particles (or holes)
with respect to the Mott insulator. Sufficiently close to the
transition, there is a broad momentum range in the Brillouin zone where
the singular part \(n^{\rm sing}_{\bf
k}=n_{\bf k}-n^{\rm MI}_{\bf k}\) of the momentum distribution
exhibits the high-momentum tail \(Z_{\rm QP}
C_{\rm univ}/|{\bf k}|^4\), where \(Z_{\rm QP}\) the quasi-particle weight of
the elementary excitations at the QCP. We argue that the contact \(C_{\rm univ}\) can be measured in
state-of-the-art experiments on Bose gases in optical lattices, and in
magnetic insulators.
Quantum Gases (cond-mat.quant-gas)
6 pages, 4 figures; see also the companion paper submitted to arXiv on the same day
Strong-coupling RPA theory of a Bose gas near the superfluid--Mott-insulator transition: universal thermodynamics and two-body contact
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Nicolas Dupuis, Nicolas Dupuis, Adam Rançon
We present a strong-coupling expansion of the Bose-Hubbard model
based on a mean-field treatment of the hopping term, while onsite
fluctuations are taken into account exactly. This random phase
approximation (RPA) describes the universal features of the generic
Mott-insulator--superfluid transition (induced by a density change) and
the superfluid phase near the phase transition. The critical
quasi-particles at the quantum critical point have a quadratic
dispersion with an effective mass \(m^\ast\) and their mutual interaction is
described by an effective \(s\)-wave
scattering length \(a^\ast\). The
singular part of the pressure takes the same form as in a dilute Bose
gas, provided we replace the boson mass \(m\) and the scattering length in vacuum
\(a\) by \(m^\ast\) and \(a^\ast\), and the density \(n\) by the excess density \(|n-n_{\rm MI}|\) of particles (or holes)
with respect to the Mott insulator. We define a
universal'' two-body contact $C_{\rm univ}$ that controls the high-momentum tail $\sim 1/|{\bf k}|^4$ of the singular part $n^{\rm sing}_{\bf k}$ of the momentum distribution. We also apply the strong-coupling RPA to a lattice model of hard-core bosons and find that the high-momentum distribution is controlled by a universal contact, in complete agreement with the Bose-Hubbard model. Finally, we discuss a continuum model of bosons in an optical lattice and define two additional two-body contacts: a short-distanceuniversal''
contact \(C_{\rm univ}^{\rm sd}\) which
controls the high-momentum tail of \(n^{\rm
sing}_{\bf k}\) at scales larger than the inverse lattice
spacing, and a ``full'' contact \(C\)
which controls the high-momentum tail of the full momentum distribution
\(n_{\bf k}\).
Quantum Gases (cond-mat.quant-gas)
20 pages, 6 figures; see also the companion paper submitted to arXiv on the same day
Partition Function Zeros of Paths and Normalization Zeros of ASEPS
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Zdzislaw Burda, Desmond A. Johnston
We exploit the equivalence between the partition function of an adsorbing Dyck walk model and the Asymmetric Simple Exclusion Process (ASEP) normalization to obtain the thermodynamic limit of the locus of the ASEP normalization zeros from a conformal map. We discuss the equivalence between this approach and using an electrostatic analogy to determine the locus, both in the case of the ASEP and the random allocation model.
Statistical Mechanics (cond-mat.stat-mech), Mathematical Physics (math-ph)
Crystalline superconductor-semiconductor Josephson junctions for compact superconducting qubits
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Jesse Balgley, Jinho Park, Xuanjing Chu, Ethan G. Arnault, Martin V. Gustafsson, Leonardo Ranzani, Madisen Holbrook, Kenji Watanabe, Takashi Taniguchi, Vasili Perebeinos, James Hone, Kin Chung Fong
The narrow bandgap of semiconductors allows for thick, uniform Josephson junction barriers, potentially enabling reproducible, stable, and compact superconducting qubits. We study vertically stacked van der Waals Josephson junctions with semiconducting weak links, whose crystalline structures and clean interfaces offer a promising platform for quantum devices. We observe robust Josephson coupling across 2--12 nm (3--18 atomic layers) of semiconducting WSe\(_2\) and, notably, a crossover from proximity- to tunneling-type behavior with increasing weak link thickness. Building on these results, we fabricate a prototype all-crystalline merged-element transmon qubit with transmon frequency and anharmonicity closely matching design parameters. We demonstrate dispersive coupling between this transmon and a microwave resonator, highlighting the potential of crystalline superconductor-semiconductor structures for compact, tailored superconducting quantum devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
A Micromechanical Model for Light-interactive Molecular Crystals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Devesh Tiwari, Ananya Renuka Balakrishna
Molecular crystals respond to a light stimulus by bending, twisting, rolling, jumping, or other kinematic behaviors. These behaviors are known to be affected by, among others, the intensity of the incident light, the aspect ratios of crystal geometries, and the volume changes accompanying phase transformation. While these factors, individually, explain the increase in internal energy of the system and its subsequent minimization through macroscopic deformation, they do not fully explain the diversity of deformations observed in molecular crystals. Here, we propose a micromechanical model based on the Cauchy-Born rule and photoreaction theory to predict the macroscopic response in molecular crystals. By accounting for lattice geometry changes and microstructural patterns that emerge during phase transformation, we predict a range of deformations in a representative molecular crystal (salicylideneamine). Doing so, we find that the interplay between photoexcited states and the energy minimization pathways, across a multi-well energy landscape, is crucial to the bending and twisting deformations. We use our model to analyze the role of particle geometries and the intensity of incident light on macroscopic deformation, and identify geometric regimes for shearing and twisting deformations in salicylideneamine crystals. Our micromechanical model is general and can be adapted to predict photomechanical deformation in other molecular crystals undergoing a solid-to-solid phase change and has potential as a computational design tool to engineer reversible and controllable actuation in molecular crystals.
Materials Science (cond-mat.mtrl-sci)
Towards perfect quantum insulation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Rafael Hipolito, Paul M. Goldbart
Electric fields, applied to insulators, cause transitions between valence and conduction bands, giving rise to current. Adjustments of the Hamiltonian can perfect the quality of the insulator, shutting down transitions whilst fully preserving the many-particle state, but they are challenging to implement. Instead, adjusted Hamiltonians having desirable features are addressed variationally, via the analysis of a suitable figure of merit. They suppress current-enabling transitions whilst tending to preserve the many-particle state, and hence they yield optimal insulation. Emerging naturally from this approach are two established concepts: transitionless quantum driving [M. V. Berry, J. Phys. A: Math. Theor. 42, 365303 (2009)] and (a modified) localization tensor [R. Resta and S. Sorella, Phys. Rev. Lett. 82, 370-373 (1999)]. The variational approach is illustrated via application to a tight-binding model. In this setting, the optimally adjusted Hamiltonian has a powerful impact on transition suppression and localization-tensor reduction, suggesting strong enhancement of insulation. These features are expected to be more general than the model that displays them.
Materials Science (cond-mat.mtrl-sci), Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
5 pages
A structural instability drives the VO2 metal-insulator transition
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Javier del Valle, Carl Willem Rischau, Artem Korshunov, David Ambrosi, Aitana Tarazaga Martin-Luengo, Ibraheem Yousef, Sara A. Lopez-Paz, Shany Neyshtadt-Ronel, Stefano Gariglio, Alexei Bosak, Sonia Francoual, Yoav Kalcheim
VO2 features concomitant structural and metal-insulator transitions. This poses a challenge for understanding the underlying mechanism: is the transition triggered by a structural or by an electronic instability? Here, we address this question by studying pre-transitional fluctuations in the metallic state. By measuring resonant diffuse X-ray scattering we find no evidence that spatial fluctuations of d-electrons are any different from those of vanadium ion cores. That is, charge and lattice remain coupled as they fluctuate jointly towards the insulating phase, strongly supporting the case that the VO2 metal-insulator transition is triggered by a structural instability. Our work offers a novel approach to solve similar problems in other strongly correlated systems.
Strongly Correlated Electrons (cond-mat.str-el)
Atomic collapse in gapped graphene: lattice and valley effects
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Jing Wang, Xiaotai Wu, Wen-Sheng Zhao, Yuhua Cheng, Yue Hu, Francois M. Peeters
We study the atomic collapse phenomenon in \(K\) and \(K'\) valley of gapped graphene. Bound states induced by Coulomb impurity in the gap turn into atomic collapse resonances as the charge increases beyond the supercritical charge \(Z_c\). \(Z_c\) increases sublinear with the band gap \(\Delta\). The atomic collapse resonances result in peaks in the LDOS at the same energies in \(K\) and \(K'\) valley, but the strong (weak) LDOS peaks in \(K\) valley are weak (strong) LDOS peaks in \(K'\) valley reminiscent of pseudospin polarization phenomenon. From a spatial LDOS analysis of the atomic collapse resonance states, we assign specific atomic orbitals to the atomic collapse resonances. Remarkably, the two \(p\) atomic orbital atomic collapse states are no longer degenerate and splits into two having lobes in different directions in the graphene plane.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Selective Hydrogen Molecule Dissociation on Ca2N Monolayer
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Gwan Woo Kim, Soonmin Jang, Gunn Kim
Developing efficient hydrogen storage and conversion technologies is essential for sustainable energy. This study investigates the catalytic potential of a dicalcium nitride (Ca2N) monolayer for hydrogen dissociation using density functional theory (DFT) and ab initio molecular dynamics (AIMD) simulations. We find that atomic hydrogen preferentially adsorbs at Ca-centered hollow sites (labeled A sites), while molecular hydrogen adsorption is limited to bridge sites (labeled B sites). AIMD simulations reveal that H2 dissociation at B sites inhibits further adsorption, suggesting a mechanism of controlled H2 dissociation. The current findings emphasize the potential of pristine Ca2N as a catalyst for H2 dissociation-related processes and motivate future investigations of its activity in hydrogen evolution reactions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
5 figures
Dynamic Modulation of Electronic and Optical Properties in GaN Bilayers by Interlayer Sliding
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
In this study, we present a first-principles investigation of the electronic and optical properties of gallium nitride (GaN) bilayers, focusing on the influence of interlayer sliding and spacing. In contrast to the earlier studies on discrete stacking configurations, we explore the dynamic evolution of the properties during transitions between stable stacking arrangements. Using density functional theory calculations, we systematically analyze the impact of these structural variations on the electronic band structure and optical absorption spectra of GaN bilayers. The analysis includes both high-symmetry stacking configurations (AA', AB', and AC') and intermediate states generated by controlled in-plane atomic displacements, thereby providing a comprehensive understanding of the property changes associated with interlayer sliding. The findings of this study provide valuable insights into the potential for tuning the electronic and optical response of two-dimensional GaN for applications in nanoscale photonic and electronic devices, where precise control over interlayer interactions and stacking is crucial.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
6 figures
Tuning Catalytic Efficiency: Thermodynamic Optimization of Zr-Doped and MXenes for HER Catalysis
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Shrestha Dutta, Rudra Banerjee
Hydrogen production via the Hydrogen Evolution Reaction (HER) is critical for sustainable energy solutions, yet the reliance on expensive platinum (Pt) catalysts limits scalability. Zirconium-doped (-doped) MXenes, such as and , emerge as transformative alternatives, combining abundance, tunable electronic properties, and high catalytic potential. Using first-principles density functional theory (DFT), we show that doping at 3% and 7% significantly enhances HER activity by reducing the work function to the optimal range of 3.5-4.5~eV and achieving near-zero Gibbs free energy () values of 0.18-0.16~eV, conditions ideal for efficient hydrogen adsorption and desorption. Bader charge analysis reveals substantial charge redistribution with enhanced electron accumulation at and sites, further driving catalytic performance. This synergy between optimized electronic structure and catalytic properties establishes -doped MXenes as cost-effective, high-performance alternatives to noble metals for HER. By combining exceptional catalytic efficiency with scalability, our work positions -doped MXenes as a breakthrough for green hydrogen production, offering a robust pathway toward renewable energy technologies and advancing the design of next-generation non-precious metal catalysts.
Materials Science (cond-mat.mtrl-sci)
Temperature-Distance Relations in Casimir Physics
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Mathias Bostrom, A. Gholamhosseinian, J. J. Marchetta, R. W. Corkery, I. Brevik
The Casimir-Lifshitz force arises from thermal and quantum mechanical fluctuations between classical bodies and becomes significant below the micron scale. We explore temperature-distance relations based on the concepts of Wick and Bohr arising from energy-time uncertainty relations. We show that temperature-distance relations similar to those arising from the uncertainty principle are found in various Casimir interactions, with an exact relation occurring in the low-temperature regime when the zero point energy contribution cancels the thermal radiation pressure contribution between two plates.
Materials Science (cond-mat.mtrl-sci)
10 pages, 1 figure
Charge density wave modulated third-order nonlinear Hall effect in 1\(T\)-VSe\(_2\) nanosheets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Zhao-Hui Chen, Xin Liao, Jing-Wei Dong, Xing-Yu Liu, Tong-Yang Zhao, Dong Li, An-Qi Wang, Zhi-Min Liao
We report the observation of a pronounced third-order nonlinear Hall effect (NLHE) in 1\(T\)-phase VSe\(_2\) nanosheets, synthesized using chemical vapor deposition (CVD). The nanosheets exhibit a charge density wave (CDW) transition at $$77 K. Detailed angle-resolved and temperature-dependent measurements reveal a strong cubic relationship between the third-harmonic Hall voltage \(V_{3\omega}^\perp\) and the bias current \(I_\omega\), persisting up to room temperature. Notably, the third-order NLHE demonstrates a twofold angular dependence and significant enhancement below the CDW transition temperature, indicative of threefold symmetry breaking in the CDW phase. Scaling analysis suggests that the intrinsic contribution from the Berry connection polarizability tensor is substantially increased in the CDW phase, while extrinsic effects dominate at higher temperatures. Our findings highlight the critical role of CDW-induced symmetry breaking in modulating quantum geometric properties and nonlinear transport phenomena in VSe\(_2\), paving the way for future explorations in low-dimensional quantum materials.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Phys. Rev. B 110, 235135 (2024)
Accurate THz Measurements of Permittivity and Permeability of BiFeO3 Thin Films
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Gian Paolo Papari, Zahra Mazaheri, Francesca Lo Presti, Graziella Malandrino, Antonello Andreone
The electrodynamic properties of BiFeO3 films in the THz region are investigated via time domain spectroscopy. Combining the use of transmission (\(\tilde{T}\)) and reflection (\(\tilde{R}\)) measurements under normal incidence, the refractive index and impedance of the samples under test are evaluated using a retrieval method. From \(\tilde{T}\)((\(\tilde{R}\))) data two complex functions describing the refractive index \(\tilde{n}_T\) (\(\tilde{n}_R\)) and impedance \(\tilde{z}_T\) (\(\tilde{z}_R\)) are extracted from the independent minimization of the error functions given by the difference between the theoretical model and measurements. Knowledge of the pairs (\(\tilde{n}_T, \tilde{n}_R\)) and (\(\tilde{z}_T, \tilde{z}_R\)) enables to calculate with a high accuracy both complex permittivity \(\tilde{\varepsilon}\) and permeability \(\tilde{\mu}\) of the sample. Signatures of magnetoelectric effects and phononic resonances are observed in the permittivity and permeability functions and discussed in detail.
Materials Science (cond-mat.mtrl-sci), Optics (physics.optics)
24 pages, 12 figures
Unravelling The potential of Hybrid Borocarbonitride Biphenylene 2D Network for Thermoelectric Applications: A First Principles Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Ajay Kumar Parbati Senapati, Prakash Parida
In this study, we investigate a novel hybrid borocarbonitrides (bpn-BCN) 2D material inspired by recent advances in carbon biphenylene synthesis, using first-principles calculations and semi-classical Boltzmann transport theory. Our analysis confirms the structural stability of bpn-BCN through formation energy, elastic coefficients, phonon dispersion, and molecular dynamics simulations at 300 K and 800 K. The material exhibits an indirect band gap of 0.19 eV (PBE) between the X and Y points and a direct band gap of 0.58 eV (HSE) at the X point. Thermoelectric properties reveal a high Seebeck coefficient, peaking at for n-type carriers at 200K along the x-axis, while n-type has a maximum of The electrical conductivity is for hole carriers, surpassing that of conventional 2D materials. The consequences of the high Seebeck coefficient and conductivity reflect a high-power factor with a peak value of at 1000K for p-type carriers along the y-axis whereas, for n-type. Moreover, the highest observed values were 0.78 (0.72) along the x (y) direction at 750 K for p-type and 0.57 (0.53) at 750 K along the x (y) axis for n-type. Our findings suggest that the bpn-BCN 2D network holds significant potential for thermoelectric applications due to its exceptional performance.
Materials Science (cond-mat.mtrl-sci)
Iron-Arsenide monolayer as an anode materials for Lithium-ion batteries: A first-principles study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
This theoretical investigation delves into the structural, electronic, and electrochemical properties of two hexagonal iron-arsenide monolayers, 1T-FeAs and 1H-FeAs, focusing on their potential as anode materials for Lithium-ion batteries. Previous studies have highlighted the ferromagnetic nature of 1T-FeAs at room this http URL calculations reveal that both phases exhibit metallic behaviour with spin-polarized electronic band structures. Electrochemical studies show that the 1T-FeAs monolayer has better ionic conductivity for Li ions than the 1H-FeAs phase, attributed to a lower activation barrier of 0.38 eV. This characteristic suggests a faster charge/discharge rate. Both FeAs phases exhibit comparable theoretical capacities 374 mAh/g, outperforming commercial graphite anodes. The average open-circuit voltage for maximum Li atom adsorption is 0.61 V for 1H-FeAs and 0.44 V for 1T-FeAs. The volume expansion over the maximum adsorption of Li atoms on both phases is also remarkably less than the commercially used anode material such as graphite. Further, the adsorption of Li atoms onto 1H-FeAs induces a remarkable transition from ferromagnetism to anti-ferromagnetism, with minimal impact on the electronic band structure. In contrast, the original state of 1T-FeAs remains unaffected by Li adsorption. To summarize, the potential of both 1T-FeAs and 1H-FeAs monolayers as promising anode materials for Lithium-ion batteries, offering valuable insights into their electrochemical performance and phase transition behaviour upon Li adsorption.
Materials Science (cond-mat.mtrl-sci)
Theoretical study of {}-5 boron monolayer as an anode material for Li and non-Li ion batteries
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
We have studied the electrochemical performance of the delta-5 boron monolayer as an anode material for alkali metal (AM) and alkali earth metal (AEM) ion batteries using density functional theory simulations. The electronic properties, adsorption, diffusion rate, and storage behavior of various metal atoms (M) in the {}-5 boron monolayer are explored. Our study shows that the delta-5 boron monolayer possesses high electrical conductivity and a low activation barrier for electron and metal ion transit (0.46-1.72 eV), indicating a fast charge/discharge rate. Furthermore, the theoretical capacities of the {}-5 boron monolayer for Li, Na, and K are found to be greater than those of commercial graphite. The average open-circuit voltage for AM and AEM is reasonably low and in the range of 0.14-0.88 V. Our results show that {}-5 boron monolayer could be a promising anode material in lithium-ion and non-lithium ion rechargeable batteries.
Materials Science (cond-mat.mtrl-sci)
Spin nematic order and superconductivity in \(J_1\)-\(J_2\) Kondo lattice model on square lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
We investigate competition and cooperation of magnetic frustration and the Kondo effect in the \(J_1\)-\(J_2\) Kondo lattice model on the square lattice at zero temperature. In this model, the frustrated interactions \(J_1,J_2\) between the localized spins stabilize spin nematic orders, while the Kondo coupling favors local spin singlets. Using the slave boson mean field approximation, we find that the spin nematic order remains stable against small Kondo coupling, and the localized spins and the conduction electrons are effectively decoupled. On the other hand, a standard Fermi liquid state is formed for sufficiently strong Kondo interactions. Furthermore, in an intermediate region with moderate Kondo coupling, the spin nematic order and the Kondo effect coexist, and superconducting pairing of the conduction electrons is induced by the spinon pairing. We discuss the ground state phase diagram and nature of the quantum phase transitions between the different superconducting states.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
12 pages
Tailoring magnetic properties of CoFeB films via tungsten buffer and capping layers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
L. Saravanan, Nanhe Kumar Gupta, Carlos Garcia, Sujeet Chaudhary
Controlling the interface between W and CoFeB-based buffer or capping layers at an appropriate temperature is essential for modifying the strength of magnetic anisotropy. In this work, we systematically explore the impact of W buffer and capping layers on the structural, topological, and magnetic anisotropy properties of W (5 nm)/CoFeB(10 nm) and CoFeB(10 nm)/W(3 nm) bilayers sputtered at room temperature (RT) and annealed at an optimal annealing temperature (TA) of 400 C. Our findings demonstrate that the bilayer films uniaxial magnetic anisotropy (UMA) with out-of-plane coercivity (Hcp) is highly influenced by the W buffer, capping layers, and TA. Specifically, the Hcp of the CoFeB layer with the buffer and capping layers annealed at 400 C samples exceed several times the coercivity of those unannealed. CoFeB buffered with W and annealed at 400 C shows larger Hcp, two-fold UMA, and higher in-plane UMA energy density (Keff) than the CoFeB/W bilayers, which can be attributed to the W buffer layer inducing the crystallization of CoFeB during annealing. The W buffer, capping layers, and the TA for W and CoFeB-based bilayer samples significantly alter the surface morphology, grain sizes, and surface roughness. The XRD analysis reveals nano-crystallites embedded in the larger grains of the 400 C annealed samples. Hence, this work offers a promising approach to achieving high thermal stability of UMA in W and CoFeB-based spintronic applications.
Materials Science (cond-mat.mtrl-sci)
Nanoscale resolved mapping of the dipole emission of hBN color centers with a scattering-type scanning near-field optical microscope
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Iris Niehues, Daniel Wigger, Korbinian Kaltenecker, Annika Klein-Hitpass, Philippe Roelli, Aleksandra K. Dąbrowska, Katarzyna Ludwiczak, Piotr Tatarczak, Janne O. Becker, Robert Schmidt, Martin Schnell, Johannes Binder, Andrzej Wysmołek, Rainer Hillenbrand
Color centers in hexagonal boron nitride (hBN) are promising candidates as quantum light sources for future technologies. In this work, we utilize a scattering-type near-field optical microscope (s-SNOM) to study the photoluminescence (PL) emission characteristics of such quantum emitters in metalorganic vapor phase epitaxy grown hBN. On the one hand, we demonstrate direct near-field optical excitation and emission through interaction with the nanofocus of the tip resulting in a sub-diffraction limited tip-enhanced PL hotspot. On the other hand, we show that indirect excitation and emission via scattering from the tip significantly increases the recorded PL intensity. This demonstrates that the tip-assisted PL (TAPL) process efficiently guides the generated light to the detector. We apply the TAPL method to map the in-plane dipole orientations of the hBN color centers on the nanoscale. This work promotes the widely available s-SNOM approach to applications in the quantum domain including characterization and optical control.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Optics (physics.optics)
A Monte Carlo examination for the numerical values of universal quantities in spatial dimension two
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
By simulating a two-dimensional (2D) dimerized spin-1/2 antiferromagnet with the quantum Monte Carlo method, the numerical values of two universal quantities associated with the quantum critical regime (QCR), namely \(S(\pi,\pi)/\left(\chi_s T\right)\) and \(c/\left(T\xi\right)\), are determined. Here \(S(\pi,\pi)\), \(\chi_s\), \(c\), \(\xi,\) and \(T\) are the staggered structure factor, the staggered susceptibility, the spin-wave velocity, the correlation length, and the temperature, respectively. For other QCR universal quantities, such as the Wilson ratio \(W\) and \(\chi_u c^2/T\) (\(\chi_u\) is the uniform susceptibility), it is shown that the addition of higher order theoretical contribution makes the agreement between the numerical and the analytic results worse. We find that the same scenario applies to \(S(\pi,\pi)/\left(\chi_s T\right)\) and \(c/\left(T\xi\right)\) as well. Specifically, our calculations lead to \(S(\pi,\pi)/\left(\chi_s T\right)\sim 1.073\) and \(c/\left(T\xi\right)\sim 0.963\) which are in better consistence with the leading theoretical predictions than those with the next-to-leading order terms. The presented outcome here as well as those in some relevant literature suggest that it is desirable to conduct a refinement of the analytic calculation to resolve the puzzle of why the inclusion of higher order terms leads to less accurate predictions for these universal quantities.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Lattice (hep-lat)
7 pages, 9 figures
Resolving Contradictory Estimates of Band Gaps of Bulk PdSe\(_2\): A Wannier-Localized Optimally-Tuned Screened Range-Separated Hybrid Density Functional Theory Study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Fred Florio, María Camarasa-Gómez, Guy Ohad, Doron Naveh, Leeor Kronik, Ashwin Ramasubramaniam
Palladium diselenide (PdSe\(_2\)) -- a layered van der Waals material -- is attracting significant attention for optoelectronics due to the wide tunability of its band gap from the infrared through the visible range as a function of the number of layers. However, there continues to be disagreement over the precise nature and value of the optical band gap of bulk PdSe\(_2\), owing to the rather small value of this gap that complicates experimental measurements and their interpretation. Here, we design and employ a Wannier-localized optimally-tuned screened range-separated hybrid (WOT-SRSH) functional to investigate the electronic bandstructures and optical absorption spectra of bulk and monolayer PdSe\(_2\). In particular, we account carefully for the finite exciton center-of-mass momentum within a time-dependent WOT-SRSH framework to calculate the optical gap and absorption onset accurately. Our results agree well with the best available photoconductivity measurements, as well as with state-of-the-art many-body perturbation theory calculations, confirming that bulk PdSe\(_2\) has an optical gap in the mid-infrared (upper-bound of 0.44 eV). More generally, this work further bolsters the utility of the WOT-SRSH approach for predictive modeling of layered semiconductors.
Materials Science (cond-mat.mtrl-sci)
Pyrochlore NaYbO2: A potential Quantum Spin Liquid Candidate
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Chuanyan Fan, Tieyan Chang, Longlong Fan, Simon J. Teat, Feiyu Li, Xiaoran Feng, Chao Liu, Shi-lei Wang, Huifen Ren, Jiazheng Hao, Zhaohui Dong, Lunhua He, Shanpeng Wang, Chengwang Niu, Yu-Sheng Chen, Xutang Tao, Junjie Zhang
The search for quantum spin liquids (QSL) and chemical doping in such materials to explore superconductivity have continuously attracted intense interest. Here, we report the discovery of a potential QSL candidate, pyrochlore-lattice beta-NaYbO2. Colorless and transparent NaYbO2 single crystals, layered alpha-NaYbO2 (~250 um on edge) and octahedral beta-NaYbO2 (~50 um on edge), were grown for the first time. Synchrotron X-ray single crystal diffraction unambiguously determined that the newfound beta-NaYbO2 belongs to the three-dimensional pyrochlore structure characterized by the R-3m space group, corroborated by synchrotron X-ray and neutron powder diffraction and pair distribution function. Magnetic measurements revealed no long-range magnetic order or spin glass behavior down to 0.4 K with a low boundary spin frustration factor of 17.5, suggesting a potential QSL ground state. Under high magnetic fields, the potential QSL state was broken and spins order. Our findings reveal that NaYbO2 is a fertile playground for studying novel quantum states.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Journal of the American Chemical Society, copyright American Chemical Society after peer review. To access the final edited and published work, a link will be provided soon
Quantum correlations and spatial localization in trapped one-dimensional ultra-cold Bose-Bose-Bose mixtures
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Tran Duong Anh-Tai, Miguel A. García-March, Thomas Busch, Thomás Fogarty
We systematically investigate and illustrate the complete ground-state phase diagram for a one-dimensional, three-species mixture of a few repulsively interacting bosons trapped harmonically. To numerically obtain the solutions to the many-body Schrödinger equation, we employ the improved Exact Diagonalization method [T. D. Anh-Tai {}, SciPost Physics 15, 048 (2023)], which is capable of treating strongly-correlated few-body systems from first principles in an efficiently truncated Hilbert space. We present our comprehensive results for all possible combinations of intra- and interspecies interactions in the extreme limits that are either the ideal limit (\(g=0\)) or close to the hard-core limit (\(g\to\infty\)). These results show the emergence of unique ground-state properties related to correlations, coherence and spatial localization stemming from strongly repulsive interactions.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
22 pages, 12 figures. Comments are welcome
A Panoramic View of MXenes via a New Design Strategy
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Noah Oyeniran, Oyshee Chowdhury, Chongze Hu, Traian Dumitrica, Panchapakesan Ganesh, Jacek Jakowski, Zhongfang Chen, Raymond R. Unocic, Michael Naguib, Vincent Meunier, Yury Gogotsi, Paul R. C. Kent, Bobby G. Sumpter, Jingsong Huang
Two-dimensional (2D) transition metal carbides and nitrides, known as MXenes, possess unique physical and chemical properties, enabling diverse applications in fields ranging from energy storage to communication, catalysis, sensing, healthcare, and beyond. The transition metal and nonmetallic atoms in MXenes can exhibit distinct coordination environments, potentially leading to a wide variety of 2D phases. Despite extensive research and significant advancements, a fundamental understanding of MXenes' phase diversity and its relationship with their hierarchical precursors, including intermediate MAX phases and parent bulk phases, remains limited. Using high-throughput modeling based on first-principles density functional theory, we unveil a wide range of MXenes and comprehensively evaluate their relative stabilities across a large chemical space. The key lies in considering both octahedral and trigonal prismatic coordination environments characteristic of various bulk phases. Through this comprehensive structural library of MXenes, we uncover a close alignment between the phase stability of MXenes and that of their hierarchical 3D counterparts. Building on this, we demonstrate a new design strategy where the atomic coordination environments in parent bulk phases can serve as reliable predictors for the design of MXenes, reducing reliance on intermediate MAX phases. Our study significantly expands the landscape of MXenes, at least doubling the number of possible structures.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
17 pages, 5 illustrations (3 figures and 2 tables)
Giant Anomalous Hall Effect in Kagome Nodal Surface Semimetal Fe\(_3\)Ge
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Shu-Xiang Li, Wencheng Wang, Sheng Xu, Tianhao Li, Zheng Li, Jinjin Wang, Jun-Jian Mi, Qian Tao, Feng Tang, Xiangang Wan, Zhu-An Xu
It is well known that the intrinsic anomalous Hall effect (AHE) arises from the integration of the non-zero Berry curvature (BC), conventionally observed in the Dirac/Weyl and nodal-line semimetals. Moreover, nodal surface semimetals are expected to exhibit more significant BC under the prevalence of degenerate points near the Fermi level. In this work, we report the detection of a giant AHE in the Kagome magnet Fe\(_3\)Ge with a two-dimensional (2D) nodal surface (NS) at \(k_{z}=\pi\) plane, exhibiting an anomalous Hall conductivity (AHC) of 1500 \(\Omega^{-1}\)cm\(^{-1}\) at 160 K, the highest among all reported Kagome topological materials. This finding suggests a new platform for searching large AHC materials and facilitates potential room-temperature applications in spintronic devices and quantum computing.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Optimizing the Critical Temperature and Superfluid Density of a Metal-Superconductor Bilayer
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Yutan Zhang, Philip M. Dee, Benjamin Cohen-Stead, Thomas A. Maier, Steven Johnston, Richard Scalettar
A promising path to realizing higher superconducting transition temperatures \(T_c\) is the strategic engineering of artificial heterostructures. For example, quantum materials exhibiting some but not all of the characteristics necessary for a robust superconducting state could, in principle, be coupled with other materials in a way that alleviates their intrinsic shortcomings. In this work, we add numerical support to the hypothesis that a strongly interacting superconductor weakened by phase fluctuations can boost its \(T_c\) by hybridizing the system with a metal. Using determinant quantum Monte Carlo (DQMC), we simulate a two-dimensional bilayer composed of an attractive Hubbard model and a metallic layer in two regimes of the interaction strength \(-|U|\). In the strongly interacting regime, we find that increasing the interlayer hybridization \(t_\perp\) results in a nonmonotonic enhancement of \(T_c\), with an optimal value comparable to the maximum \(T_c\) observed in the single-layer attractive Hubbard model, confirming trends inferred from other approaches. In the intermediate coupling regime, when \(-|U|\) is close to the value associated with the maximum \(T_c\) of the single-layer model, increasing \(t_\perp\) tends to decrease \(T_c\), implying that the correlated layer was already optimally tuned. Importantly, we demonstrate that the mechanism behind these trends is related to enhancement in the superfluid stiffness, as was initially proposed by Kivelson [Physica B: Condensed Matter 318, 61 (2002)].
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
The Connection between Spin Wave Polarization and Dissipation
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Yutian Wang, Jiongjie Wang, Ruoban Ma, Jiang Xiao
This study establishes a fundamental connection between the dissipation and polarization of spin waves, which are often treated as independent phenomena. Through theoretical analysis and numerical validation, we demonstrate that within the linearized spin wave regime, a spin wave mode's dissipation rate, defined as the ratio of linewidth to the resonance frequency, exceeds Gilbert damping by a factor given by its spatially averaged polarization. This average is governed by a non-positive definite weight, whose magnitude depends on the magnon density of the local excitation, while its sign is dictated by the local polarization handedness. Remarkably, this universal connection applies across diverse magnetic interactions and textures, offering crucial insights into spin wave dynamics and dissipation.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 2 figures
Spin-imbalance induced buried topological edge currents in Mott & topological insulator heterostructures
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Rahul Ghosh, Subhajyoti Pal, Kush Saha, Anamitra Mukherjee
We theoretically investigate the heterostructure between a ferrimagnetic Mott insulator and a time-reversal invariant topological band insulator on the two-dimensional Lieb lattice with periodic boundary conditions. Our Hartree-Fock and slave-rotor mean-field results incorporate long-range Coulomb interactions. We present charge and magnetic reconstructions at the two edges of the heterostructure and reveal how topological edge modes adapt to these heterostructure edge reconstructions. In particular, we demonstrate that the interface magnetic field induces a spin imbalance in the edge modes while preserving their topological character and metallic nature. We show that this imbalance leads to topologically protected buried spin and charge currents. The inherent spin-momentum locking ensures that left and right movers contribute to the current at the two buried interfaces in opposite directions. We show that the magnitude of the spin-imbalance induced charge and spin current can be tuned by adjusting the spin-orbit coupling of the bulk topological insulator relative to the correlation strength of the bulk Mott insulator. Thus, our results demonstrate a controlled conversion of a spin Hall effect into an analog of a charge Hall effect driven by band topology and interaction effects. These topologically protected charge and spin currents pave the way for advances in low-energy electronics and spintronic devices.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Synthetic Gauge Field for Ultracold Atoms Induced by Vector Beams
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Huan Wang, Shangguo Zhu, Yun Long, Mingbo Pu, Xiangang Luo
Vector beams (VBs) with spatially varying polarization have broad applications across various fields of optics. We introduce a novel use of VBs to generate synthetic gauge fields for ultracold atoms. By leveraging VBs' rich tunability, this scheme enables the emergence of angular stripe phases over a significantly expanded parameter range, achieving a three-orders-of-magnitude enhancement in the phase diagram and thereby making experimental observation feasible. It also allows for the creation of topologically nontrivial giant skyrmions in spin space, with tunable topology controlled by VB parameters and without requiring rotation. Our work opens new avenues for utilizing VBs in quantum control of ultracold atoms and the exploration of exotic quantum states and phases.
Quantum Gases (cond-mat.quant-gas), Atomic Physics (physics.atom-ph), Optics (physics.optics), Quantum Physics (quant-ph)
7 pages, 3 figures + Supplementary Material (8 pages, 3 figures)
Transverse Field Dependence of the Ground State in the Z2 Bose-Hubbard Model
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Yuma Watanabe, Shohei Watabe, Tetsuro Nikuni
The study of interaction between the particle and lattice degrees of freedom is one of the central interests in the quantum many-body systems. The Z2 Bose-Hubbard model has been proposed to describe ultracold bosons in a dynamical optical lattice. This model introduces the lattice degrees of freedom by placing half-spins on the bonds between neighboring lattice sites. In this study, we investigate the effect of spin fluctuations on the ground state by using the density-matrix renormalization group method. By calculating the spin structure factor and the compressibility, we show that there is a phase transition between two spatially nonuniform states. We also discuss the ground state in the strong transverse magnetic field.
Quantum Gases (cond-mat.quant-gas)
Bi-Josephson Effect in a Driven-Dissipative Supersolid
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Jieli Qin, Shijie Li, Yijia Tu, Maokun Gu, Lin Guan, Weimin Xu, Lu Zhou
The Josephson effect is a macroscopic quantum tunneling phenomenon in a system with superfluid property, when it is split into two parts by a barrier. Here, we examine the Josephson effect in a driven-dissipative supersolid realized by coupling Bose-Einstein condensates to an optical ring cavity. We show that the spontaneous breaking of spatial translation symmetry in supersolid makes the location of the splitting barrier have a significant influence on the Josephson effect. Remarkably, for the same splitting barrier, depending on its location, two different types of DC Josephson currents are found in the supersolid phase (compared to only one type found in the superfluid phase). Thus, we term it a bi-Josephson effect. We examine the Josephson relationships and critical Josephson currents in detail, revealing that the emergence of supersolid order affects these two types of DC Josephson currents differently -- one is enhanced, while the other is suppressed. The findings of this work unveil unique Josephson physics in the supersolid phase, and show new opportunities to build novel Josephson devices with supersolids.
Quantum Gases (cond-mat.quant-gas)
New J. Phys. 27 013015 (2025)
Complete classification of integrability and non-integrability of S=1/2 spin chains with symmetric next-nearest-neighbor interaction
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
We study S=1/2 quantum spin chains with shift-invariant and inversion-symmetric next-nearest-neighbor interaction, also known as zigzag spin chains. We completely classify the integrability and non-integrability of the above class of spin systems. We prove that in this class there are only two integrable models, a classical model and a model solvable by the Bethe ansatz, and all the remaining systems are non-integrable. Our classification theorem confirms that within this class of spin chains, there is no missing integrable model. This theorem also implies the absence of intermediate models with a finite number of local conserved quantities.
Statistical Mechanics (cond-mat.stat-mech), Strongly Correlated Electrons (cond-mat.str-el), Mathematical Physics (math-ph), Quantum Physics (quant-ph)
71 pages, no figure
Determination of the London penetration depth with the tunnel diode oscillator technique
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Using a distribution of the Meissner currents over the surface of an infinitely long superconducting slab with a rectangular cross section, the magnetic moment of the slab is calculated, taking into account corrections associated with a small but finite value of the London penetration depth \(\lambda\). Since these corrections determine the shift of the resonant frequency in the tunnel diode oscillator technique, formulas for determination of \(\lambda\) within this technique are derived for the slab. These formulas are valid for any aspect ratio of its cross section, and they differ from those that are often used in analyzing experimental data. Namely, it is shown that sharp edges of the slab can cause the large frequency shift proportional to the change in the value of \(\lambda^{2/3}\). Although this result complicates the extraction of a temperature dependence of \(\lambda\) from the frequency shift, it also opens up new possibilities in determining the London penetration depth. In particular, under certain conditions, it is possible not only to measure the changes in \(\lambda\) with the temperature, but also to estimate its absolute value.
Superconductivity (cond-mat.supr-con)
12 pages, 6 figures, to be published in Phys. Rev. B
Improving accuracy of tree-tensor network approach by optimization of network structure
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Toshiya Hikihara, Hiroshi Ueda, Kouichi Okunishi, Kenji Harada, Tomotoshi Nishino
Numerical methods based on tensor networks have been extensively explored in the research of quantum many-body systems in recent years. It has been recognized that the ability of tensor networks to describe a quantum many-body state crucially depends on the spatial structure of the network. In the previous work, we proposed an algorithm based on tree tensor networks (TTNs) that automatically optimizes the structure of TTN according to the spatial profile of entanglement in the state of interest. In this paper, we precisely analyze how detailed updating schemes in the structural optimization algorithm affect its computational accuracy for the random XY-exchange model under random magnetic fields and the Richardson model. We then find that for the random XY model, on the one hand, the algorithm achieves improved accuracy, and the stochastic algorithm, which selects the local network structure probabilistically, is notably effective. For the Richardson model, on the other hand, the resulting numerical accuracy subtly depends on the initial TTN and the updating schemes. In particular, the algorithm without the stochastic updating scheme certainly improves the accuracy, while the one with the stochastic updates results in poor accuracy due to the effect of randomizing the network structure at the early stage of the calculation. These results indicate that the algorithm successfully improves the accuracy of the numerical calculations for quantum many-body states, while it is essential to appropriately choose the updating scheme as well as the initial TTN structure, depending on the systems treated.
Statistical Mechanics (cond-mat.stat-mech), High Energy Physics - Lattice (hep-lat), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
19 pages, 15 figures, 2 tables
Simultaneous Superconducting and Topological Properties in Mg-Li Electrides at High Pressures
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
D. Wang, H. Song, Q. Hao, G. Yang, H. Wang, L. Zhang, Y. Chen, X. Chen, Hua Y. Geng
Electrides as a unique class of emerging materials exhibit fascinating properties and hold important significance for understanding the matter under extreme conditions, which is characterized by valence electrons localized into the interstitial space as quasi-atoms (ISQs). In this work, using crystal structure prediction and first-principles calculations, we identified seven stable phases of Mg-Li that are electride with novel electronic properties under high pressure. Among them, MgLi10 is a semiconductor with a band gap of 0.22 eV; and Pm-3m MgLi is superconductor with a superconducting transition temperature of 22.8 K. The important role played by the localization degree of ISQ in the superconducting transition temperature of these electrides is revealed by systematic comparison of Mg-Li with other Li-rich electride superconductors. Furthermore, we proved that Pm-3m MgLi and Pnma MgLi also have distinct topological behavior with metallic surface states and the non-zero \(Z_2\) invariant. The simultaneous coexistence of superconductivity, electronic band topology and electride property in the same structure of Pm-3m MgLi and Pnma MgLi demonstrates the feasibility of realizing multi-quantum phases in a single material, which will stimulate further research in these interdisciplinary fields.
Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph), Quantum Physics (quant-ph)
38 pages, 7 figures, with Supporting Information
J. Phys. Chem. C 129, 689-698 (2025)
Gate Tunable Josephson Diode Effect in Josephson Junctions made from InAs Nanosheets
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Shili Yan, Yi Luo, Haitian Su, Han Gao, Xingjun Wu, Dong Pan, Jianhua Zhao, Ji-Yin Wang, Hongqi Xu
We report the observation of Josephson diode effect (JDE) in hybrid devices made from semiconductor InAs nanosheets and superconductor Al contacts. By applying an in-plane magnetic field (\(B_{\mathrm{xy}}\)), we detect non-reciprocal superconducting switching current as well as non-reciprocal superconducting retrapping current. The strength of the JDE depends on the angle between the in-plane magnetic field and the bias current (\(I_{\mathrm{b}}\)), reaching its maximum when \(B_{\mathrm{xy}} \perp I_{\mathrm{b}}\) and dropping to nearly zero when \(B_{\mathrm{xy}}\parallel I_{\mathrm{b}}\). Additionally, the diode efficiency is tunable via an electrostatic gate with a complete suppression at certain gate voltages. Our findings indicate that the observed JDE in InAs nanosheet-based Josephson junctions most likely arises from the Rashba spin-orbit interaction (SOI) in the nanosheets. Such gate-tunable JDE in Josephson junctions made from semiconductor material with SOI is useful not only for constructing advanced superconducting electronics but also for detecting novel superconducting states.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Pressure induced Structure Change and Anomalies in Thermodynamic Quantities and Transport Properties in Liquid Lithium Hydride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
X. Z. Yan, Y. M. Chen, Hua Y. Geng, Y. F. Wang, Y. Sun, L. L. Zhang, H. Wang, Y. L. Xu
Understand the nature of liquid structure and its evolution under different conditions is a major challenge in condensed physics and materials science. Here, we report a pressure-induced structure change spanning a wide pressure range in liquid-state lithium hydride (LiH) by first-principles molecular dynamic simulations. This behavior can be described as a continuous crossover from low pressure liquid with Li\(^+\)-H\(^-\) duality symmetry to high pressure one with broken of duality symmetry. The thermodynamic quantities such as heat capacity and ionic transport properties such as diffusivity are also saliently impacted. It is important to stress that such behavior is firstly predicted for this category of materials, which is ubiquitous in universe as well as in industry applications. Lastly, a comprehensive high-pressure high-temperature phase diagram of LiH is constructed, which embodies rich physics in this previously-thought-simple ionic compound.
Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Applied Physics (physics.app-ph), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
23 pages, 4 figures, with Supplementary Information
Phys. Rev. B 111, 024102 (2025)
Dispersive measurement of spin shot noise in a Bose--Einstein condensate
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Kosuke Shibata, Naota Sekiguchi, Junnosuke Takai, Takuya Hirano
We report dispersive spin shot noise measurement of a Bose--Einstein condensate (BEC). While dispersive probing has been used for quantum spin noise measurement of thermal and cold gases for decades, confirmative measurement of spin shot noise, i.e., the linear dependence of the spin variance on the number of atoms in a BEC has been lacking. Here, we demonstrate precise spin noise measurement of a BEC of rubidium atoms at the spin shot noise level by polarization rotation using a two-color probe at optimal detunings, with power balance stabilization to suppress probe-induced excess spin noise. This work opens the possibility for the unexplored study of quantum spin fluctuations in multi-component or spinor BECs and offers an approach to improve spin measurement precision, which is relevant to atomic spin-based sensors.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
6 pages, 3 figures
Mixing and Ergodicity in Systems with Long-Range Interactions
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Tarcísio Nunes Teles, Renato Pakter, Yan Levin
We present a theory of collisionless relaxation in systems with long-range interactions. Contrary to Lynden-Bell's theory of violent relaxation, which assumes global ergodicity and mixing, we show that quasi-stationary states (qSS) observed in these systems exhibit broken global ergodicity. We propose that relaxation towards equilibrium occurs through a process of local mixing, where particles spread over energy shells defined by the manifold to which their trajectories are confined. To demonstrate our theory, we study the Hamiltonian Mean Field (HMF) model, a paradigmatic system with long-range interactions. Our theory accurately predicts the particle distribution functions in qSS observed in molecular dynamics simulations without any adjustable parameters. Additionally, it precisely forecasts the phase transitions observed in the HMF model.
Statistical Mechanics (cond-mat.stat-mech)
6 pages, 4 figures;
First-principle based Floquet engineering of solids in the velocity gauge
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
We introduce a practical and accurate strategy to capture light-matter interactions using the Floquet formalism in the velocity gauge in combination with realistic first-principle models of solids. The velocity gauge, defined by the linear coupling to the vector potential, is a standard method to capture the light-matter interaction in solids. However, its use with first-principle models has been limited by the challenging fact that it requires a large number of bands for convergence and its incompatibility with non-local pseudopotential plane wave methods. To improve its convergence properties, we explicitly take into account the truncation of Hilbert space in the construction of the Floquet Hamiltonian in the velocity gauge. To avoid the incompatibility with the pseudopotentials, we base our computations on generalized tight-binding Hamiltonians derived from first-principles through maximally-localized Wannier functions. We exemplify the approach by computing the optical absorption spectra of laser-dressed trans-polyacetylene chain using realistic electronic structure. We show that, by proceeding in this way, Floquet consideration involving the truncated Hilbert spaces reproduces the full basis calculations with only a few bands and with significantly reduced computation time. The strategy has been implemented in FloqticS, a general code for the Floquet engineering of the optical properties of materials. Overall, this work introduces a useful theoretical tool to realize Floquet engineering of realistic solids in the velocity gauge.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph), Optics (physics.optics)
The Impact of Mechanical Strain on Magnetic and Structural Properties of 2D Materials: A Monte Carlo study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
The inherent flexibility of two dimensional materials allows for efficient manipulation of their physical properties through strain application, which is essential for the development of advanced nanoscale devices. This study aimed to understand the impact of mechanical strain on the magnetic properties of two dimensional materials using Monte Carlo simulations. The effects of several strain states on the magnetic properties were investigated using the Lennard Jones potential and bond length-dependent exchange interactions. The key parameters analyzed include the Lindemann coefficient, radial distribution function, and magnetization in relation to temperature and magnetic field. The results indicate that applying biaxial tensile strain generally reduces the critical temperature. In contrast, the biaxial compressive strain increased Tc within the elastic range, but decreased at higher strain levels. Both compressive and tensile strains significantly influence the ferromagnetic properties and structural ordering, as evidenced by magnetization hysteresis. Notably, pure shear strain did not induce disorder, leaving the magnetization unaffected. In addition, our findings suggest the potential of domain-formation mechanisms. This study provides comprehensive insights into the influence of mechanical strain on the magnetic behavior and structural integrity of 2D materials, offering valuable guidance for future research and advanced material design applications.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph), Computational Physics (physics.comp-ph)
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Chem. Phys. 161, 124705 (2024) and may be found at this https URL
This article published in J. Chem. Phys. 161, 124705 (2024)
Sensitive particle shape dependence of growth-induced mesoscale nematic structure
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
Directed growth, anisotropic cell shapes, and confinement drive self-organization in multicellular systems. We investigate the influence of particle shape on the distribution and dynamics of nematic microdomains in a minimal in-silico model of proliferating, sterically interacting particles, akin to colonies of rod-shaped bacteria. By introducing continuously tuneable tip variations around a common rod shape with spherical caps, we find that subtle changes significantly impact the emergent dynamics, leading to distinct patterns of microdomain formation and stability. Our analysis reveals separate effects of particle shape and aspect ratio, as well as a transition from exponential to scale-free size distributions, which we recapitulate using an effective master equation model. This allows us to relate differences in microdomain size distributions to different physical mechanisms of microdomain breakup. Our results thereby contribute to the characterization of the effective dynamics in growing aggregates at large and intermediate length scales and the microscopic properties that control it. This could be relevant both for biological self-organization and design strategies for future artificial systems.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
7 pages, 6 figures
Floquet optical selection rules in black phosphorus
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Benshu Fan, Umberto De Giovannini, Hannes Hübener, Shuyun Zhou, Wenhui Duan, Angel Rubio, Peizhe Tang
The optical selection rules endorsed by symmetry are crucial for understanding the optical properties of quantum materials and the associated ultrafast spectral phenomena. Herein, we introduce momentum-resolved Floquet optical selection rules using the group theory to elucidate the pump-probe photoemission spectral distributions of monolayer black phosphorus (BP), which are governed by the symmetries of both the material and the lasers. Using time-dependent density functional theory (TDDFT), we further investigate the dynamical evolution of Floquet(-Volkov) states in the photoemission spectra of monolayer BP, revealing their spectral weights at specific momenta for each sideband. These observations are comprehensively explained by the proposed Floquet optical selection rules. Our framework not only clarifies experimental photoemission spectra but also uncovers novel characteristics under different pump-probe configurations. Our results are expected to deepen the understanding of light-induced ultrafast spectra in BP and can be further extended to other Floquet systems.
Materials Science (cond-mat.mtrl-sci)
Anomalous temperature-dependent magnetization in the nearly collinear antiferromagnet Y\(_2\)Co\(_3\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Yunshu Shi, Huibo Cao, Hung-Cheng Wu, Li Yin, Neil Harrison, David S. Parker, Tushar Bhowmick, Tessa McNamee, Fatemeh Safari, Sergey L. Budko, James C. Fettinger, Susan M. Kauzlarich, Peter Klavins, Dmitry Popov, Ravhi Kumar, Russell J. Hemley, Shanti Deemyad, Taku J. Sato, Paul. C. Canfield, Valentin Taufour
Y\(_2\)Co\(_3\) is a newly discovered antiferromagnetic (AFM) compound with distorted kagome layers. Previous investigations via bulk magnetization measurements suggested a complex noncollinear magnetic behavior, with magnetic moments primarily anti-aligned along the \(b\) axis and some canting towards the \(ac\) plane. In this study, we report the magnetic structure of Y\(_2\)Co\(_3\) to be an A-type AFM structure with ferromagnetic (FM) interactions within the distorted kagome plane and an interplane antiferromagnetic interaction, as determined by single-crystal neutron diffraction. The magnetic moments align along the \(b\) axis, with minimal canting towards the \(c\) axis, at odds with the previous interpretation of bulk magnetization measurements. The magnetic moments on the two distinct Co sites are [0, -0.68(3), 0] \(\mu_B\) and [0, 1.25(4), 0.07(1)] \(\mu_B\). We attribute the previously reported "noncollinear" behavior to the considerable temperature dependence of itinerant AFM exchange interactions, induced by thermal contraction along the \(b\) axis. Additionally, our examination of lattice constants through pressure studies reveals compensating effects on FM and AFM interactions, resulting in negligible pressure dependence of \(T_\textrm{N}\).
Strongly Correlated Electrons (cond-mat.str-el)
Physical Review B 110,235159 (2024)
The significance of "stripes" in the physics of the cuprates, the Hubbard model, and other highly correlated electronic systems
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Thomas P. Devereaux, Steven A. Kivelson
"Stripes" - meaning unidirectional charge-density-waves, sometimes (but not always) accompanied by spin-density-waves with twice the period - are now known to arise in broad swathes of the cuprate phase diagram, and appear as a strong ordering tendency in numerical studies of Hubbard-like models of highly correlated electron systems. Jan Zaanen's work played a seminal role in predicting their existence, and exploring their possible significance. They are {} related to any weak-coupling physics associated with some form of Fermi-surface nesting. And whether one likes them or not, they are surprisingly difficult to avoid; in the Hubbard model, for example, they often appear as an alternative order that can out-compete the otherwise favored \(d\)-wave superconductivity.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Quasi-aperiodic grain boundary phases in {}5 tilt grain boundaries in refractory metals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
We report new quasi-aperiodic, ground-state structures and phase transitions in \(\Sigma5\) tilt grain boundaries (GBs) in body-centered cubic (BCC) refractory metals Nb, Ta, Mo, and W. \(\Sigma5\) tilt GBs have been extensively investigated over the past several decades, with their ground-state structure -- composed of kite-shaped structural units -- previously thought to be well understood. By performing a rigorous GB structure search that optimizes the number of atoms in the boundary core, we predict new quasi-aperiodic "split kite" phases analogous to those previously found in GBs in face-centered cubic metals. Our results suggest that complex aperiodic phases of GBs appear to be a general phenomenon. Density functional theory calculations yield similar GB energies and structures for kite and split kite phases in all BCC metals studied. Phase-contrast image simulations of split kites show better agreement with experimental observations, offering an alternative explanation for previous microscopy results and motivating future atomically resolved imaging of the GB structure.
Materials Science (cond-mat.mtrl-sci)
The geometric impact of the quantum Hall interface on a cone
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Recently, quantum Hall interface has become a popular subject of research; distinct from that of the quantum Hall edge, which is constrained by external background confinement, the interface has the freedom to move, likely towards a string-like state. In disk geometry, it was known that the interface energy has an extra correction due to its curvature which depends on the size of the disk. In this work, we analytically calculate the energy of the integer quantum Hall interface on a cone surface which has the advantage that its curvature is more easily adjustable. By tuning the length and curvature of the interface by the cone angle parameter \(\beta\), we analyze the dependence of the quantum Hall interface energy on the curvature and verify this geometric correction. Moreover, we find that the tip of the cone geometry has an extra contribution to the energy that reflects on the \(u_2,u_4\) term.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
8 pages, 7 figures
An ab initio dataset of size-dependent effective thermal conductivity for advanced technology transistors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Han Xie, Ru Jia, Yonglin Xia, Lei Li, Yue Hu, Jiaxuan Xu, Yufei Sheng, Yuanyuan Wang, Hua Bao
As the size of transistors shrinks and power density increases, thermal simulation has become an indispensable part of the device design procedure. However, existing works for advanced technology transistors use simplified empirical models to calculate effective thermal conductivity in the simulations. In this work, we present a dataset of size-dependent effective thermal conductivity with electron and phonon properties extracted from ab initio computations. Absolute in-plane and cross-plane thermal conductivity data of eight semiconducting materials (Si, Ge, GaN, AlN, 4H-SiC, GaAs, InAs, BAs) and four metallic materials (Al, W, TiN, Ti) with the characteristic length ranging from 5 to 50 nanometers have been provided. Besides the absolute value, normalized effective thermal conductivity is also given, in case it needs to be used with updated bulk thermal conductivity in the future. The dataset presented in this paper are openly available at this https URL.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Electrically driven resonant magnetization, spin-pumping and charge-to-spin conversion from chiral-spin modes at THz frequencies
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Mojdeh Saleh, Abhishek Kumar, Dmitrii L. Maslov, Saurabh Maiti
Chiral-spin modes are collective excitations of a spin-orbit (SO) coupled system that lead to resonances in many observables. Here we identify resonances in "cross-response", i.e., electric-field induced magnetization and magnetic-field induced electric currents, known also as the Edelstein effect and its inverse, respectively. We show that the chiral-spin modes resonantly enhance the electrically induced magnetization. As specific examples, we consider a single-valley two-dimensional electron gas with Rashba or Dresselhaus SO coupling and a two-valley Dirac system with proximity-induced Rashba and valley-Zeeman SO couplings. We suggest an architecture for a spin-pumping experiment based on THz excitation of chiral-spin modes, which would demonstrate a resonant enhancement of charge-to-spin conversion.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Magnon-mediated perpendicular magnetization switching by topological crystalline insulator SnTe with high spin Hall conductivity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Pengnan Zhao, Guoyi Shi, Wentian Lu, Lihuan Yang, Hui Ru Tan, Kaiwei Guo, Jia-Min Lai, Zhonghai Yu, Anjan Soumyanarayanan, Zhe Yuan, Fei Wang, Xiaohong Xu, Hyunsoo Yang
Magnons possess the ability to transport spin angular momentum in insulating magnetic materials, a characteristic that sets them apart from traditional electronics where power consumption arises from the movement of electrons. However, the practical application of magnon devices demands room temperature operation and low switching power of perpendicular magnetization. Here we demonstrate the low-power manipulation of perpendicular magnetization via magnon torques in SnTe/NiO/CoFeB devices at room temperature. Topological crystalline insulator SnTe exhibits a high spin Hall conductivity of \(\sigma_s \approx 6.1\times 10^4 (\hbar/2e)\cdot (\Omega \cdot m)^{-1}\), which facilitates the generation of magnon currents in an antiferromagnetic insulator NiO. The magnon currents traverse the 20-nm-thick NiO layer and subsequently exert magnon torques on the adjacent ferromagnetic layer, leading to magnetization switching. Notably, we achieve a 22-fold reduction in power consumption in SnTe/NiO/CoFeB heterostructures compared to Bi2Te3/NiO/CoFeB control samples. Our findings establish the low-power perpendicular magnetization manipulation through magnon torques, significantly expanding the range of topological materials with practical applications.
Materials Science (cond-mat.mtrl-sci)
45 pages, 28 figures
On Virial Expansion in Hard Sphere Model
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Virial expansion is a traditional approach in statistical mechanics that expresses thermodynamic quantities, such as pressure \(p\), as power series of density or chemical potential. Its radius of convergence can serve as a potential indicator of phase transition. In this study, we investigate the virial expansion of the hard-sphere model, using the known dimensionless virial coefficients \(\tilde{B}_k^{}~(k=1,2,\cdots)\) up to the \(12\)th order. We find that it is well fitted by \(\tilde{B}_k^{}=1.28\times k^{1.90}\), corresponding to the analytic continuation of the virial expansion of the pressure as \(\sim \mathrm{Li}_{-1.90}^{}(\eta)\), where \(\eta\) is the packing fraction and \(\mathrm{Li}_s^{}(x)\) is the polylogarithm function. This implies the absence of singular behavior in the physical parameter space \(\eta\leq \eta_{\mathrm{max}}^{}\approx 0.74\) and no indication of phase transition in the virial expansion approach. In addition, we calculate the cluster-integral coefficients \(\{b_l^{}\}_{l=1}^\infty\) and observe that their asymptotic behavior resembles the results obtained in the large dimension limit (\(D\rightarrow \infty\)), suggesting that \(D=3\) might be already regarded as large dimension. However, the existence of phase transition in the hard-sphere model has been confirmed by numerous simulations, which clearly indicates that a naive extrapolation of the virial series can lead to unphysical results.
Statistical Mechanics (cond-mat.stat-mech), Materials Science (cond-mat.mtrl-sci)
14 pages, 2 figures
Absence of two-phonon quasi-elastic scattering in the normal state of doped--SrTiO\(_3\) by THz pump-probe spectroscopy
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
K. Santhosh Kumar, David Barbalas, Rishi Bhandia, Dooyong Lee, Shivasheesh Varshney, Bharat Jalan, N. P. Armitage
Multi-pulse nonlinear THz spectroscopies enable a new understanding of interacting metallic systems via their sensitivity to novel correlation functions. Here, we investigated the THz nonlinear properties of the dilute metallic phase of doped-SrTiO\(_3\) thin films using nonlinear terahertz 2D coherent spectroscopy. We observed a large \(\chi^{(3)}\) response in the low temperature region where the dc electrical resistivity follows a T\(^2\)-dependence. This is largely a pump-probe response, which we find is governed by a single energy relaxation rate that is much smaller at all temperatures than the momentum relaxation rates obtained from the optical conductivity. This indicates that the processes that dominate the resistive scattering are not the same as those that remove energy from the electronic system. Moreover the fact that the energy relaxation rate is an increasing function of temperature indicates that the excitations that do carry away energy from the electronic system cannot be considered as quasi-elastic and as such soft two-phonon electron scattering does not play a major role in the physics as proposed. This indicates that these materials' resistive T\(^2\) scattering likely originates in electron-electron interactions despite the very small Fermi wave vectors at the lowest dopings.
Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
Submitted. Supplemental Material
Overdoping YBa2Cu3O7 via a heterostructure with La0.67Sr0.33MnO3
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Ankita Singh, Sawani Datta, Ram Prakash Pandeya, Srinivas C. Kandukuri, Mahesh Gokhale, Kalobaran Maiti
YBa2Cu3Ox, the first superconductor discovered with Tc higher than 77 K, is among the most complex cuprates having both CuO chains and plains in the structure. YBa2Cu3O7 (YBCO) exhibits slightly overdoped behavior and further doping is difficult as all the lattice sites in the CuO chains are occupied. We have grown high quality single crystalline films of YBCO and bilayer La0.67Sr0.33MnO3 (LSMO)/YBCO exhibiting superconductivity in both the cases. Photoemission spectra reveal different surface and bulk electronic structures; the difference reduces in the bilayer. Evidence of charge transfer across the bilayer interface is observed in the valence band and core level spectra indicating an overdoped condition in YBCO. While superconductivity in the presence of magnetic order in the bilayer is puzzling, this pathway to reach overdoped regime in YBCO opens up a new landscape to probe the exotic physics of unconventional superconductivity.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
Reliable Density Functional Theory Predictions of Bandgaps for Materials
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Chenxi Lu, Musen Li, Michael J. Ford, Rika Kobayashi, Roger Amos, Jeffrey R.Reimers
We consider methods for optimizing the bandgap calculation of 3D materials, considering 340 sample materials. Examined are the effects of the choice of the pseudopotential to describe core electrons, the plane-wave basis set cutoff energy, and the Brillouin zone integration. Cost-saving calculations in which the structure is optimized using reduced-quality Brillouin zone integrations and cutoff energies were found to lead to experimentally significant errors exceeding 0.1 eV in 18% of cases using the PBE functional and 21% of cases using PBE0. Such cost-savings approaches are therefore not recommended for general applications. Also, the current practice of using unoptimized grids to perform the Brillouin-zone integrations in bandgap calculations is found to be unreliable for 16% of materials using PBE and for 23% using PBE0. A k-space optimization scheme is introduced that interpolates extensive PBE results to determine a generally useful approach that when used in PBE0 calculations is found to be inadequate for only 1.6% of the materials studied.
Materials Science (cond-mat.mtrl-sci)
Investigation of Sub-configurations Reveals Stable Spin-Orbit Torque Switching Polarity in Polycrystalline Mn3Sn
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Boyu Zhao, Zhengde Xu, Xue Zhang, Zhenhang Kong, Shuyuan Shi, Zhifeng Zhu
Previous studies have demonstrated the switching of octupole moment in Mn3Sn driven by spin-orbit torque (SOT). However, they have not accounted for the polycrystalline nature of the sample when explaining the switching mechanism. In this work, we use samples with various atomic orientations to capture this polycrystalline nature. We thoroughly investigate their SOT-induced spin dynamics and demonstrate that the polycrystalline structure leads to distinct outcomes. Our findings reveal that configuration II, where the Kagome plane is perpendicular to the spin polarization, exhibits robust switching with stable polarity, whereas the signals from various sub-configurations in configuration I cancel each other out. By comparing our findings with experimental results, we pinpoint the primary sources contributing to the measured AHE signals. Additionally, we establish a dynamic balance model that incorporates the unique properties of Mn3Sn to elucidate these observations. Our study highlights the essential role of the polycrystalline nature in understanding SOT switching. By clarifying the underlying physical mechanisms, our work resolves the longstanding puzzle regarding the robust SOT switching observed in Mn3Sn.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Nonlinear valley thermal physics in two dimensional materials
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
This study delves into the intrinsic nonlinear valley thermal effects, driven by the Quantum Metric of the system. Our findings elucidate that valley indices in the nonlinear effect are distinguishable by the thermoelectric correction to the orbital magnetization, which adopts opposite signs across valleys mirroring the role of orbital angular momentum in the linear valley Hall effect. Through a prototypical two-band model on an anisotropic tilted Dirac semimetal, we investigate how intrinsic material parameters modulate this nonlinear valley thermal response. Extending to realistic PT symmetric anisotropic semiconductors, our findings enrich the understanding of valley-based phenomena, with implications for advanced theoretical and experimental pursuits in valleytronics and valley caloritonics.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
CrySPAI: A new Crystal Structure Prediction Software Based on Artificial Intelligence
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Zongguo Wang, Ziyi Chen, Yang Yuan, Yangang Wang
Crystal structure predictions based on the combination of first-principles calculations and machine learning have achieved significant success in materials science. However, most of these approaches are limited to predicting specific systems, which hinders their application to unknown or unexplored domains. In this paper, we present CrySPAI, a crystal structure prediction package developed using artificial intelligence (AI) to predict energetically stable crystal structures of inorganic materials given their chemical compositions. The software consists of three key modules, an evolutionary optimization algorithm (EOA) that searches for all possible crystal structure configurations, density functional theory (DFT) that provides the accurate energy values for these structures, and a deep neural network (DNN) that learns the relationship between crystal structures and their corresponding energies. To optimize the process across these modules, a distributed framework is implemented to parallelize tasks, and an automated workflow has been integrated into CrySPAI for seamless execution. This paper reports the development and implementation of AI AI-based CrySPAI Crystal Prediction Software tool and its unique features.
Materials Science (cond-mat.mtrl-sci), Artificial Intelligence (cs.AI)
Self-Adapted Josephson Oscillation of Dark-Bright Solitons under Constant Forces
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Ling-Zheng Meng, Xi-Wang Luo, Li-Chen Zhao
We study the propagation of dark-bright solitons in two-component Bose-Einstein condensates (BECs) with general nonlinear parameters, and explore how nonlinear interactions enrich the soliton dynamics giving rise to nonsinusoidal oscillations under constant forces. Treating the bright soliton as an effective barrier, we reveal that such oscillations are characterized by the Josephson equations with self-adapted critical current and bias voltage, whose explicit analytic expressions are derived using the Lagrangian variational method. The dynamical phase diagram in nonlinear parameter space is presented, identifying oscillation regions with different skewed sinusoidal dependence, and diffusion regions with irreversible soliton spreading due to instability of the barrier. Furthermore, we obtain periodic dispersion relations of the solitons, indicating a switch between positive and negative inertial masses, consistent with the oscillation behaviors. Our results provide a general and comprehensive theoretical framework for soliton oscillation dynamics and pave the way for investigating various nonlinear transports and their potential applications.
Quantum Gases (cond-mat.quant-gas), Pattern Formation and Solitons (nlin.PS)
9 pages, 5 figures
Mapping Sandpiles to Complex Networks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Abbas Shoja-Daliklidash, Morteza Nattagh-Najafi, Nasser Sepehri-Javan
In this paper, we address a longstanding challenge in self-organized criticality (SOC) systems: establishing a connection between sandpiles and complex networks. Our approach employs a similarity-based transfer function characterized by two parameters, \(\mathcal{R}=(r_1, r_2)\). Here, \(r_1\) quantifies the similarity of local activities, while \(r_2\) governs the filtration process used to convert a weighted network into a binary one. We reveal that the degree centrality distribution of the resulting network follows a generalized Gamma distribution (GGD), which transitions to a power-law distribution under specific conditions. The GGD exponents, estimated numerically, exhibit a dependency on \(\mathcal{R}\). Notably, while both decreasing \(r_1\) and \(r_2\) lead to denser networks, \(r_2\) plays a more significant role in influencing network density. Furthermore, the Shannon entropy is observed to decrease linearly with increasing \(r_2\), whereas its variation with \(r_1\) is more gradual. An analytical expression for the Shannon entropy is proposed. To characterize the network structure, we investigate the clustering coefficient (\(cc\)), eigenvalue centrality (\(e\)), closeness centrality (\(c\)), and betweenness centrality (\(b\)). The distributions of \(cc\), \(e\), and \(c\) exhibit peaked profiles, while \(b\) displays a power-law distribution over a finite interval of \(k\). Additionally, we explore correlations between the exponents and identify a specific parameter regime of \(\mathcal{R}\) and \(k\) where the \(e-k\), \(c-k\), and \(b-k\) correlations become negative.
Statistical Mechanics (cond-mat.stat-mech)
Probing Glass Formation in Perylene Derivatives via Atomic Scale Simulations and Bayesian Regression
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Eric Lindgren, Jan Swensson, Christian Müller, Paul Erhart
While the structural dynamics of chromophores are of interest for a range of applications, it is experimentally very challenging to resolve the underlying microscopic mechanisms. Glassy dynamics are also challenging for atomistic simulations due to the underlying dramatic slowdown over many orders of magnitude. Here, we address this issue by combining atomic scale simulations with autocorrelation function analysis and Bayesian regression, and apply this approach to a set of perylene derivatives as prototypical chromophores. The predicted glass transition temperatures and kinetic fragilities are in semi-quantitative agreement with experimental data. By analyzing the underlying dynamics via the normal vector autocorrelation function, we are able to connect the beta and alpha-relaxation processes in these materials to caged (or librational) dynamics and cooperative rotations of the molecules, respectively. The workflow presented in this work serves as a stepping stone toward understanding glassy dynamics in many-component mixtures of perylene derivatives and is readily extendable to other systems of chromophores.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
8 pages, 5 figures
Thermoelectric properties of magic angle twisted bilayer graphene-superconductor hetero-junction: effect of valley polarization and trigonal warping
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Kamalesh Bera, Pritam Chatterjee, Priyanka Mohan, Arijit Saha
We theoretically investigate the thermoelectric properties (electronic contribution) of a normal-superconductor (NS) hybrid junction, where the normal region consists of magic-angle twisted bilayer graphene (MATBG). The superconducting region is characterized by a common \(s\)-wave superconductor closely proximitized to the MATBG. We compute various thermoelectric coefficients, including thermal conductance, thermopower, and the figure of merit (\(zT\)), using the scattering matrix formalism. These results are further supported by calculations based on a lattice-regularized version of the effective Hamiltonian. Additionally, we explore the impact of trigonal warping and valley polarization on the thermoelectric coefficients. Notably, we find a significant variation in \(zT\) as a function of these parameters, reaching values as high as 2.5. Interestingly, we observe a violation of the Wiedemann-Franz law near the charge neutrality point with the superconducting correlation, indicating that MATBG electrons behave as slow Dirac fermions in this regime. This observation is further confirmed by the damped oscillatory behavior of the thermal conductance as a function of the barrier strength when an insulating barrier is modelled at the interface of the NS junction. Beyond theoretical insights, our findings suggest new possibilities for thermoelectric applications using MATBG based NS junctions.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
12 Pages, 7 PDF Figures, Comments are welcome
Eigenstate solutions of the Fermi-Hubbard model via symmetry-enhanced variational quantum eigensolver
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
The Variational Quantum Eigensolver (VQE), as a hybrid quantum-classical algorithm, is an important tool for effective quantum computing in the current noisy intermediate-scale quantum (NISQ) era. However, the traditional hardware-efficient ansatz without taking into account symmetries requires more computational resources to explore the unnecessary regions in the Hilbert space. The conventional Subspace-Search VQE (SSVQE) algorithm, which can calculate excited states, is also unable to effectively handle degenerate states since the loss function only contains the expectation value of the Hamiltonian. In this study, the energy eigenstates of the one-dimensional Fermi-Hubbard model with two lattice sites and the two-dimensional Hubbard model with four lattice sites are calculated. By incorporating symmetries into the quantum circuits and loss function, we find that both the ground state and excited state calculations are improved greatly compared to the case without symmetries. The enhancement in excited state calculations is particularly significant. This is because quantum circuits that conserve the particle number are used, and appropriate penalty terms are added to the loss function, enabling the optimization process to correctly identify degenerate states. The results are verified through repeated simulations.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
16 pages, 5 figures, 10 tables
A flux-controlled two-site Kitaev chain
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Ivan Kulesh, Sebastiaan L. D. ten Haaf, Qingzhen Wang, Vincent P. M. Sietses, Yining Zhang, Sebastiaan R. Roelofs, Christian G. Prosko, Di Xiao, Candice Thomas, Michael J. Manfra, Srijit Goswami
In semiconducting-superconducting hybrid devices, Andreev bound states (ABSs) can mediate the coupling between quantum dots (QDs), allowing for the realisation of artificial Kitaev chains. In order to engineer Majorana bound states (MBSs) in these systems, one must control the energy of the ABSs. In this work, we show how extended ABSs in a flux tunable Josephson junction can be used to control the coupling between distant quantum dots separated by \(\approx\) 1 \(\mathrm{\mu}\)m. In particular, we demonstrate that the combination of electrostatic control and phase control over the ABSs significantly increases the parameter space in which MBSs are observed. Finally, by employing an additional spectroscopic probe in the hybrid region between the QDs, we gain information about the spatial distribution of the Majorana wave function in a two-site Kitaev chain.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Superconductivity (cond-mat.supr-con)
13 pages - 4 main figures, 10 supplementary figures
Low volume fraction of high-Tc superconductivity in La3Ni2O7 at 80 K and ambient pressure
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Mengwu Huo, Peiyue Ma, Chaoxin Huang, Xing Huang, Hualei Sun, Meng Wang
The discovery of superconductivity in pressurized La3Ni2O7 with a transition temperature of approximately 80 K above the boiling point of liquid nitrogen has sparked significant attention. It is essential to search for high-temperature superconductivity in bulk samples and at ambient pressure in nickelates. In this study, we report influential factors that affect the appearance of superconductivity in La3Ni2O7 at ambient pressure. From direct-current magnetic measurements, we observe a clear diamagnetic response at 80 K in post-annealed single crystals of La3Ni2O7 in oxygen. The superconducting volume fraction is estimated to be within 0.2%, resulting in a decrease in resistivity. This work presents a practical approach for further investigating high-temperature superconductivity in nickelates at ambient pressure.
Superconductivity (cond-mat.supr-con)
4 figures, 11 pages
Spin fluctuations steer electronic behavior and altermagnetism in the FeSb\(_{3}\) skutterudite
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Enrico Di Lucente, Flaviano José dos Santos, Nicola Marzari
Skutterudites are promising materials for thermoelectric and spintronics applications. Here we explore spin fluctuations in the FeSb\(_{3}\) skutterudite and their effect on its electronic structure using Hubbard-corrected density-functional theory calculations. We identify multiple magnetic and charge-disproportionated configurations, with an antiferromagnetic metallic ground state. Paramagnetic fluctuations modeled through a special quasirandom spin structure open a 61 meV gap, consistent with experiments. This state features non-degenerate spin channels and band-avoided crossings, hinting at a potential altermagnetic transition with topological features. Mapping the electronic structure to a Heisenberg Hamiltonian fails to explain the low Néel temperature ($$10 K), highlighting the role of magnetic exchange frustration and the need for more in-depth experimental investigations.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
6 pages, 2 figures
Magnetoelastic coupling in the stretched diamond lattice of TbTaO\(_4\)
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Xiaotian Zhang, Nicola Kelly, Denis Sheptyakov, Cheng Liu, Shiyu Deng, Siddharth Saxena, Siân Dutton
The magnetic structure of diamond-like lattice has been studied extensively in terms of the magnetic frustration. Here we report the distortion of stretched diamond lattice of Tb\(^{3+}\) (4\(f^8\)) in M-TbTaO\(_4\) on application of a magnetic field. We have investigated the structural and magnetic properties of M phase terbium tantalate M-TbTaO\(_4\) as a function of temperature and magnetic field using magnetometry and powder neutron diffraction. Sharp \({\lambda}\)-shape transitions in \(d(\chi T)/dT\), \(dM/dH\) and specific heat data confirm the previously reported three-dimensional (3D) antiferromagnetic ordering at \(T_N \approx 2.25\) K. On application of a magnetic field the Néel temperature is found to decrease and variable field neutron diffraction experiments below \(T_N\) at 1.6 K show an increase in both the bond and angle distortion of the stretched diamond lattice with magnetic field, indicating a potential magneto-elastic coupling effect. By combining our magnetometry, heat capacity and neutron diffraction results we generate a magnetic phase diagram for M-TbTaO\(_4\) as a function of temperature and field.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
9 pages main text plus 12 pages supplemental information
Band gap renormalization, carrier mobility and transport in Mg2Si and Ca2Si: Ab-initio scattering and Boltzmann transport equation study
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Vinod Kumar Solet, Sudhir K. Pandey
We perform first-principles electron-phonon interaction (EPI) calculations based on many-body perturbation theory to study the temperature-dependent band-gap and charge-carrier transport properties for Mg\(_{2}\)Si and Ca\(_{2}\)Si using the Boltzmann transport equation (BTE) under different relaxation-time approximations (RTAs). For a PBE band gap of 0.21 (0.56) eV in Mg\(_{2}\)Si (Ca\(_{2}\)Si), a zero-point renormalization correction of 29-33 (37-51) meV is obtained using various approaches, while the gap at 300 K is 0.15-0.154 (0.46-0.5) eV. The electron mobility (\(\mu_{e}\)), with a detailed convergence study at 300 K, is evaluated using linearized (self-energy and momentum RTA, or SERTA and MRTA) and iterative BTE (IBTE) solutions. At 300 K, the \(\mu_{e}\) values are 351 (100), 573 (197), and 524 (163) cm\(^{2}V^{-1}s^{-1}\) from SERTA, MRTA, and IBTE, respectively, for Mg\(_{2}\)Si (Ca\(_{2}\)Si). SERTA (MRTA) provides results in better agreement with IBTE at higher (lower) temperatures, while SERTA-derived \(\mu_{e}\) closely matches experimental \(\mu_{e}\) values for Mg\(_{2}\)Si. Thermoelectric (TE) transport coefficients significantly influenced by the choice of RTA, with SERTA and MRTA yielding improved agreement with experimental results compared to constant RTA (CRTA) for Mg\(_{2}\)Si over an electron concentration range of \(10^{17}\) to \(10^{20}\) cm\(^{-3}\). The lattice thermal conductivity (\(\kappa_{ph}\)) at 300 K due to phonon-phonon interactions is estimated to be 22.7 (7.2) W m\(^{-1}K^{-1}\) for Mg\(_{2}\)Si (Ca\(_{2}\)Si). The highest calculated figure of merit (zT) under CRTA is 0.35 (0.38), which decreases to 0.08 (0.085) when EPI is included using MRTA. This study clearly identifies the critical role of EPI in accurate transport predictions of TE silicides. Finally, we explore strategies to enhance zT by reducing \(\kappa_{ph}\) through nanostructuring and mass-difference scattering.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Non-reciprocal interactions drive emergent chiral crystallites
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
S. J. Kole, Xichen Chao, Abraham Mauleon-Amieva, Ryo Hanai, C. Patrick Royall, Tanniemola B. Liverpool
We study a new type of 2D active material that exhibits macroscopic phases with two emergent broken symmetries: self-propelled achiral particles that form dense hexatic clusters, which spontaneously rotate. We experimentally realise active colloids that self-organise into both polar and hexatic crystallites, exhibiting exotic emergent phenomena. This is accompanied by a field theory of coupled order parameters formulated on symmetry principles, including non-reciprocity, to capture the non-equilibrium dynamics. We find that the presence of two interacting broken symmetry fields leads to the emergence of novel chiral phases built from (2D) achiral active colloids (here Quincke rollers). These phases are characterised by the presence of both clockwise and counterclockwise rotating clusters. We thus show that spontaneous rotation can emerge in non-equilibrium systems, even when the building blocks are achiral, due to non-reciprocally coupled broken symmetries. This interplay leads to self-organized stirring through counter-rotating vortices in confined colloidal systems, with cluster size controlled by external electric fields.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Single-shot capable surface acoustic wave dispersion measurement of a layered plate
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Georg Watzl, Stefan Eder, Martin Ryzy, Mike Hettich, Edgar Scherleitner, Martin Schagerl, Clemens Grünsteidl
Established techniques for characterizing a layer on a substrate system via surface acoustic wave (SAW) dispersion measurement are often slow due to the need for scanning excitation or detection positions. We present a method for determining discrete points on the SAW mode at equidistant wavenumbers that requires only a single measurement, overcoming these speed limitations. A pulsed laser, shaped into an array of equidistant lines, generates elastic waves on the sample surface. A vibrometer detects the resulting surface displacement next to the line array. The periodic excitation arrangement results in constructive interference of the SAW at wavelengths corresponding to integer fractions of the line spacing. This leads to distinct peaks in the response spectrum, whose higher orders we term spatial harmonics of the SAW. The known line spacing determines the wavelengths, allowing the peak frequencies to be mapped to discrete points on the SAW dispersion curve, effectively sampling the SAW at specific equidistant wavenumbers. By solving an inverse problem, a model can be fit to the experimental data to obtain properties of the layered system. We demonstrate this technique on copper-clad epoxy laminate and roll-cladded aluminum alloy plates and compare our results with dispersion relation scans and micrography. Additionally, we analyze the method's sensitivity to elastic parameters and layer thickness. This approach offers a viable alternative to established SAW scanning methods, particularly in scenarios where the trade-off of lower wavenumber sampling density is acceptable to achieve exceptionally fast measurements while avoiding moving parts.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph), Classical Physics (physics.class-ph), Computational Physics (physics.comp-ph), Optics (physics.optics)
submitted to Applied Physics Letters
Binary random packing fraction of hyperspheres with small or large size difference: a geometric approach
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
The random packing fraction of binary particles in D-dimensional Euclidean space R^D is studied using a geometric approach. First, the binary packing fraction of assemblies with small size difference are studied, using the excluded volume model by Onsager for particles in three-dimensional space (D = 3). According to this model the packing increase by bidispersity is proportional to (1 - f)(u^D - 1)^2, with f as monosized packing fraction, u as size ratio and D as space dimension. The model predictions are compared with computational results for disks in two dimensions (D = 2) and hyperspheres in the large-dimension limit (D to infinity), yielding good agreement. Subsequently, the packing of hyperspheres with large size difference is modeled, employing the classic theory of Furnas. This theory, developed for three dimensions, starts from an infinite size ratio of larger and smaller particles (u to infinity). Here, the pertaining equations are applied to hyperspheres, and successfully compared with computational results for hyperspheres in the large-dimension limit. Furthermore, an asymptotic approximation of the binary packing fraction for large size ratio is derived, which shows that the first order variation of the Furnas packing fraction (u^-1 = 0) is proportional to (2 - f)u^-1. Finally, a scaled D-dimensional binary packing graph is presented, governing a simplified phase diagram that borders the binary random packing fraction of amorphous assemblies. To summarize, basic space-filling and geometric (a-thermal) theories on simple hard spheres appear to be a valuable tool for the study of hyperspheres packing and amorphization.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
11 pages, 6 figures, 6 tables
Superstructure reflexions in tilted perovskites Part 1
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Richard Beanland, Robin Sjokvist
The superstructure spots that appear in diffraction patterns of tilted perovskites are well documented and easily calculated using crystallographic software. Here, by considering a distortion mode as a perturbation of the prototype perovskite structure, we show how the structure factor equation yields Boolean conditions for the presence of first order superstructure reflexions. A subsequent article describes conditions for second order reflexions, which appear only in structures with mixed in-phase and anti-phase oxygen octahedral tilting. This approach may have some advantages for the analysis of electron diffraction patterns of perovskites.
Materials Science (cond-mat.mtrl-sci)
11 pages, 1 figure
Acta Cryst. (2024). A80, 387-390
Superstructure reflexions in tilted perovskites part 2
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Richard Beanland, Robin Sjokvist
In a previous article (Beanland & Sjokvist, 2024), we derived Boolean conditions for the appearance of superstructure reflexions in diffraction patterns from perovskites with tilted oxygen octahedra, using the structure factor equation. Assuming that the deviation from the untilted prototype perovskite structure was infinitesimally small, we expanded the structure factor as a Taylor series, truncated at the first term. This gave an elegant and simple method giving conditions on the presence or absence of superstructure reflexions. However, in real perovskite materials these distortions are sufficiently large for higher order terms to become significant, giving an additional set of superstructure reflexions. Here, we consider the second term in the expansion and show that it gives rise to second order reflexions with indices of the form half-even-even-odd. Boolean conditions for their presence are given.
Materials Science (cond-mat.mtrl-sci)
180pages, 2 figures
Beyond traditional box-covering: Determining the fractal dimension of complex networks using a fixed number of boxes of flexible diameter
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-28 20:00 EST
Michal Lepek, Kordian Makulski, Agata Fronczak, Piotr Fronczak
In this paper, we present a novel box-covering algorithm for analyzing the fractal properties of complex networks. Unlike traditional algorithms that impose a predefined box size, our approach assigns nodes to boxes identified by the nearest local hubs without rigid distance constraints. This flexibility directly relates to the recently proposed scaling theory of fractal complex networks and is clearly consistent with the idea of hidden metric spaces in which network nodes are embedded. It also allows us to determine the box dimension of various real and model-based complex networks more accurately, including those previously unrecognized as fractal, such as the Internet at the level of autonomous systems. We show that our algorithm not only significantly reduces computational complexity compared to the classical greedy coloring method but also enables more precise determination of various scaling exponents describing the structure of fractal networks.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Computational Physics (physics.comp-ph), Data Analysis, Statistics and Probability (physics.data-an)
11 pages, 5 figure, pseudocode included
Circular dichroism in resonant inelastic x-ray scattering from birefringence in CuO
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Abhishek Nag, Gérard Sylvester Perren, Hiroki Ueda, A. T. Boothroyd, D. Prabhakaran, M. García-Fernández, S. Agrestini, Ke-Jin Zhou, Urs Staub
Resonant inelastic x-ray scattering (RIXS) has become a prominent technique to study quasiparticle excitations. With advances in polarization analysis capabilities at different facilities, RIXS offers exceptional potential for investigating symmetry-broken quasiparticles like chiral phonons and magnons. At optical wavelengths birefringence can severely affect polarization states in low-symmetry systems. Here we show its importance for soft x-ray resonances. Given the growing interest in Circular Dichroism (CD) in RIXS, it is important to evaluate how birefringence may affect the RIXS spectra of anisotropic systems. We investigate CuO, a well-known anisotropic material, using Cu \(L_3\)-edge RIXS and detect significant CD in both magnetic and orbital excitations in the collinear antiferromagnetic phase. We demonstrate that the CD can be modeled by a proper treatment of RIXS scattering amplitudes derived from single-ion calculations with birefringence. Recognizing these effects is crucial for unambiguous identification of subtle dichroic effects induced by symmetry-broken quasiparticles. Furthermore, the combined sensitivity of RIXS and birefringence to local symmetry presents an opportunity to study microscopic changes driven by external perturbations.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
Main Text of 7 Pages including references and 4 figures. Supplementary of 6 pages appended
Strain-time engineering via exciton interactions
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Maurício F. C. Martins Quintela, Miguel Sá, Alejandro J. Uría-Álvarez, Mikhail Malakhov, Giovanni Cistaro, Jorge Quereda, Juan J. Palacios, Antonio Picón
The technology to produce attosecond pulses opens the door to manipulate electrons in matter before their loss of quantum coherence. In two-dimensional materials, where excitonic interactions dominate the optical response, a laser-induced quantum superposition of excitons may induce a migration of charge across the system. Here, instead of tailoring the laser pulse in order to control the exciton superposition, we propose strain as a more feasible and robust scheme to control exciton migration. Uniaxial strain may break the crystal symmetry and lift the degeneracy of 1s exciton states. We show in monolayer hBN a precise control of the exciton oscillation between different valleys via strain. We perform numerical simulations of the laser-driven electron dynamics that demonstrate this effect. This work paves the way of using strain for tailoring exciton oscillations at the attosecond time scale.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
10 pages, 4 figures in main text; 11 pages, 8 figures in supplementary material
Self-propelled particles undergoing cyclic transitions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
Cyclic transitions between active and passive states are central to many natural and synthetic systems, ranging from light-driven active particles to animal migrations. Here, we investigate a minimal model of self-propelled Brownian particles undergoing cyclic transitions across three spatial zones: gain, loss, and neutral regions. Particles become active in the gain region, passive in the loss region, and retain their state in the neutral region. By analyzing the steady-state behavior as a function of particle number and the size of the loss region, we identify a threshold particle number, below and above which distinct structural changes are observed. Interestingly, below this threshold, increasing the particle number reduces the state-switching time (the time required for a particle to transition from active to passive and back to active). In contrast, above the threshold, further increases in particle number result in longer switching times. In the subthreshold regime, our analytical model predicts structural characteristics and switching dynamics that align well with simulations. Above the threshold, we observe an emergent spatial clustering, with particles transitioning from passive to active states in close proximity. These findings provide insights into the collective dynamics of cyclic processes between active and passive states across distinct spatial zones in active matter systems.
Soft Condensed Matter (cond-mat.soft)
13 pages,9 figures
A generative material transformer using Wyckoff representation
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Pierre-Paul De Breuck, Hashim A. Piracha, Miguel A. L. Marques
Materials play a critical role in various technological applications. Identifying and enumerating stable compounds, those near the convex hull, is therefore essential. Despite recent progress, generative models either have a relatively low rate of stable compounds, are computationally expensive, or lack symmetry. In this work we present Matra-Genoa, an autoregressive transformer model built on invertible tokenized representations of symmetrized crystals, including free coordinates. This approach enables sampling from a hybrid action space. The model is trained across the periodic table and space groups and can be conditioned on specific properties. We demonstrate its ability to generate stable, novel, and unique crystal structures by conditioning on the distance to the convex hull. Resulting structures are 8 times more likely to be stable than baselines using PyXtal with charge compensation, while maintaining high computational efficiency. We also release a dataset of 3 million unique crystals generated by our method, including 4,000 compounds verified by density-functional theory to be within 0.001 eV/atom of the convex hull.
Materials Science (cond-mat.mtrl-sci)
14 pages, 10 figures
Braiding Majoranas in a linear quantum dot-superconductor array: Mitigating the errors from Coulomb repulsion and residual tunneling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Sebastian Miles, Francesco Zatelli, A. Mert Bozkurt, Michael Wimmer, Chun-Xiao Liu
Exchanging the positions of two non-Abelian anyons transforms between many-body wavefunctions within a degenerate ground-state manifold. This behavior is fundamentally distinct from fermions, bosons and Abelian anyons. Recently, quantum dot-superconductor arrays have emerged as a promising platform for creating topological Kitaev chains that can host non-Abelian Majorana zero modes. In this work, we propose a minimal braiding setup in a linear array of quantum dots consisting of two minimal Kitaev chains coupled through an ancillary, normal quantum dot. We focus on the physical effects that are peculiar to quantum dot devices, such as interdot Coulomb repulsion and residual single electron tunneling. We find that the errors caused by either of these effects can be efficiently mitigated by optimal control of the ancillary quantum dot that mediates the exchange of the non-Abelian anyons. Moreover, we propose experimentally accessible methods to find this optimal operating regime and predict signatures of a successful Majorana braiding experiment.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Physics (quant-ph)
17 pages, 8 figures
Irreversible thermodynamics and Glansdorff-Prigogine principle derived from stochastic thermodynamics
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Tânia Tomé, Mário J. de Oliveira
We derive the main equations of irreversible thermodynamic including the expression for the Glansdorff-Prigogine extremal principle from stochastic thermodynamics. To this end, we analyze a system that is subject to gradients of temperature and external forces that induce the appearance of fluxes of several sorts and the creation of entropy. We show that the rate of entropy production is a convex function of the fluxes, from which follows that the excess entropy production is nonnegative, which is an expression of the Glansdorff-Prigogine principle. We show that the Lyapunov function associated with the excess entropy production can be identified with a thermodynamic potential in the special case where the gradients of temperature are absent.
Statistical Mechanics (cond-mat.stat-mech)
Overlay-aware Variation Study of Flip FET and Benchmark with CFET
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Wanyue Peng, Haoran Lu, Jingru Jiang, Jiacheng Sun, Ming Li, Runsheng Wang, Heng Wu, Ru Huang
In this work, we carried out an overlay-aware variation study on Flip FET (FFET) considering the impact on RC parasitics induced by the lithography misalignment in backside processes, and benchmarked it with CFET in terms of the power-performance (PP) and variation sources. The iso-leakage frequency degrades up to 2.20% with layout misalignment of 4 nm. It's found that the Drain Merge resistance degrades significantly with misalignment increasing and is identified as the major variation source. Through careful DTCO with design rule optimization, the variation can be greatly suppressed, while the resistance fluctuation of the DM also drops substantially. Monte Carlo random experiments were also conducted, validating the variation reduction. Comparing with the CFET featuring self-aligned gate and much less overlay induced misalignment, fortunately, FFET's PP is still better except when misalignment reaches 8 nm, which is out of spec and nearly impossible. Considering the variabilities induced by the high aspect ratio processes, CFET still faces big challenges compared with FFET.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Accepted by EDTM 2025
Proc. of EDTM 2025
Environment-limited transfer of angular momentum in Bose liquids
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Alberto Cappellaro, Giacomo Bighin, Igor Cherepanov, Mikhail Lemeshko
Impurity motion in a many-body environment has been a central issue in the field of low-temperature physics for decades. In bosonic quantum fluids, the onset of a drag force experienced by point-like objects is due to collective environment excitations, driven by the exchange of linear momentum between the impurity and the many-body bath. In this work we consider a rotating impurity, with the aim of exploring how angular momentum is exchanged with the surrounding bosonic environment. In order to elucidate this issues, we employ a quasiparticle approach based on the angulon theory, which allows us to effectively deal with the non-trivial algebra of quantized angular momentum in presence of a many-body environment. We uncover how impurity dressing by environmental excitations can establish an exchange channel, whose effectiveness crucially depends on the initial state of the impurity. Remarkably, we find that there is a critical value of initial angular momentum, above which this channel effectively freezes.
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Chemical Physics (physics.chem-ph)
15 pages, 4 figures, accepted for publication in The Journal of Chemical Physics
Density-Functional Perturbation Theory with Numeric Atom-Centered Orbitals
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Connor L. Box, Reinhard J. Maurer, Honghui Shang, Matthias Scheffler, Volker Blum, Christian Carbogno, Mariana Rossi
This paper represents one contribution to a larger Roadmap article reviewing the current status of the FHI-aims code. In this contribution, the implementation of density-functional perturbation theory in a numerical atom-centered framework is summarized. Guidelines on usage and links to tutorials are provided.
Materials Science (cond-mat.mtrl-sci)
The hidden architecture of equilibrium self-assembly
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
Maximilian C. Hübl, Thomas E. Videbæk, Daichi Hayakawa, W. Benjamin Rogers, Carl P. Goodrich
Experiments have reached a monumental capacity for designing and synthesizing microscopic particles for self-assembly, making it possible to precisely control particle concentrations, shapes, and interactions. However, we lack a comprehensive inverse-design framework for tuning these particle-level attributes to obtain desired system-level assembly outcomes, like the yield of a user-specified target structure. This severely limits our ability to take full advantage of this vast design space to assemble nanomaterials with complex structure and function. Here we show that a hidden mathematical architecture controls equilibrium assembly outcomes and provides a single comprehensive view of the entire design space. This architecture predicts which structures can be assembled at high yield and reveals constraints that govern the coexistence of structures, which we verify through detailed, quantitative assembly experiments of nanoscale particles synthesized using DNA origami. Strong experimental agreement confirms the importance of this underlying architecture and motivates its use as a predictive tool for the rational design of self-assembly. These results uncover a universal core logic underpinning all equilibrium self-assembly that forms the basis for a robust inverse-design framework, applicable to a wide array of systems from biological protein complexes to synthetic nanomachines.
Soft Condensed Matter (cond-mat.soft)
Superlubric sliding ferroelectricity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Sliding ferroelectricity may emerge in many van der Waals bilayers/multilayers and the low switching barriers render ultrafast data writing with low energy cost. We note that such barriers are still much higher compared with structural superlubricity, and in this paper we propose a type of superlubric sliding ferroelectricity in homobilayers separated by a different layer that leads to unprecedented low switching barriers due to incommensurate interfaces. For example, the switching barrier of 3R bilayer MoS2 will be respectively reduced by around 2 or 1 order of magnitudes if they are separated by a graphene or BN monolayer, and the required voltage for switching can be about 1 order of magnitude lower. Such superlubric sliding ferroelectricity widely exists in various similar sandwich trilayer systems where the polarizations stem from symmetry breaking in across-layer stacking configurations, and with ultralow barriers of superlubric sliding, their performances for various applications are greatly enhanced compared with homobilayer sliding ferroelectrics.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Effect of Anisotropic Peierls Barrier on the Evolution of Discrete Dislocation Networks in Ni
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
John D. Shimanek, Darshan Bamney, Laurent Capolungo, Zi-Kui Liu, Allison M. Beese
Over low and intermediate strain rates, plasticity in face centered cubic (FCC) metals is governed by the glide of dislocations, which manifest as complex networks that evolve with strain. Considering the elastic anisotropy of FCC metals, the characteristics of dislocation motion are also anisotropic (i.e., dislocation character angle-dependent), which is expected to notably influence the overall evolution of the dislocation network, and consequently, the plastic response of these materials. The aggregate influence of the anisotropy in the Peierls stress on the mechanical response of single crystal Ni was investigated in the present work using discrete dislocation dynamics simulations. Twenty initial dislocation networks, differing in their configuration and dislocation density, were deformed under uniaxial tension up to at least 0.9% strain, and the analysis of character-dependent dynamics showed a suppression of plasticity only for segments of nearly screw character. While the increased screw component of the Peierls stress raised the initial strain hardening rate, it also resulted in longer dislocation segments overall, contrary to the reasoning that longer pinned segments exhibit a lower resistance to motion and might give a weaker response. A non-linear superposition principle is demonstrated to predict the hardening reasonably well, considering the cumulative effects of forest and Peierls stress-related strengthening. Further analysis of the network topology revealed a tendency to maintain connectivity over the course of deformation for those networks simulated using an unequal Peierls stress. The general increases in hardening rate and network connectivity contrast with the localized reduction of dislocation motion, which occurred mainly for segments of nearly screw-type character.
Materials Science (cond-mat.mtrl-sci)
Additional analysis of stress-drop statistics during the observed intermittent plasticity is reported in the accepted manuscript (doi:https://doi.org/10.1088/1361-651X/adad8f). Data hosted on Zenodo (doi:https://doi.org/10.5281/zenodo.14712409)
Exactly Solvable Models of Interacting Chiral Bosons and Fermions on a Lattice
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
We consider one-dimensional theories of chiral fermions and bosons on a lattice, which arise as edge states of two-dimensional topological matter breaking time-reversal invariance. We show that hard core bosons or their spin chain equivalent exhibit properties that are similar to free fermions, solving the many-body problem exactly. For fermions, we study the effect of a static impurity exactly and show the orthogonality catastrophe in the continuum limit via bosonization. The interacting many-fermion problem in the continuum limit is solved exactly using simple momentum conservation arguments.
Quantum Gases (cond-mat.quant-gas)
14 pages, 2 figures
Quantum Transport with Spin Orbit Coupling: New Developments in TranSIESTA
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Nils Wittemeier, Nick Papior, Mads Brandbyge, Zeila Zanolli, Pablo Ordejón
We present the implementation of spinor quantum transport within the non-equilibrium Green's function (NEGF) code TranSIESTA based on Density Functional Theory (DFT). First-principles methods play an essential role in molecular and material modelling, and the DFT+NEGF approach has become a widely-used tool for quantum transport simulation. Exisiting (open source) DFT-based quantum transport codes either model non-equilibrium/finite-bias cases in an approximate way or rely on the collinear spin approximation. Our new implementation closes this gap and enables the TranSIESTA code to use full spinor-wave functions. Thereby it provides a method for transport simulation of topological materials and devices based on spin-orbit coupling (SOC) or non-collinear spins. These materials hold enormous potential for the development of ultra-low energy electronics urgently needed for the design of sustainable technology. The new feature is tested for relevant systems determining magnetoresistance in iron nanostructures and transport properties of a lateral transition metal dichalcogenide heterojunction.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Melting through Barrier-Crossing: The Role of Equilibrium Thermally Activated Particles
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Melting is often understood in purely equilibrium terms, where crystalline order disappears once the free energy of the solid equals that of the liquid. Yet at the microscopic level, the initiating events for melting can often be traced to the formation of defects or local ``jumps'' over interatomic barriers. In this work, we offer a unified interpretation of melting by focusing on the equilibrium fraction of particles whose energy exceeds a characteristic barrier (E_a). We show that when this fraction surpasses a small but critical threshold (on the order of (10{-4})-(10{-3})), the crystal loses its rigidity, thus reconciling Born's mechanical-instability picture with the older Lindemann notion of large atomic displacements. We derive this threshold condition from standard Boltzmann (and Bose/Fermi) statistics, ensuring consistency with standard thermodynamics. Our approach naturally extends to vortex lattices in superconductors (where vortex activation energies play the role of (E_a)) and to quantum-lattice systems (Hubbard-type models). Crucially, while the interpretation emphasizes barrier crossing, the criterion itself is built on equilibrium statistical mechanics, offering a transparent link between defect formation rates and the macroscopic transition.
Superconductivity (cond-mat.supr-con), Statistical Mechanics (cond-mat.stat-mech)
3 figures
Revisiting the phonon theory of liquid heat capacity: low-frequency shear modes and intramolecular vibrations
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
Modeling the heat capacity of liquids present fundamental difficulties due to the strong intermolecular particle interactions and large diffusive-like displacements. Based on the experimental evidence that the microscopic dynamics of liquids closely resemble those of solids, a phonon theory of liquid thermodynamics has been developed. Despite its success, the phonon theory of liquids relies on the questionable assumption that low-frequency shear excitations are propagating in nature and follow a Debye density of states. Furthermore, the same framework does not capture the contribution of intramolecular vibrations, which play a significant role in molecular liquids. In this work, we revisit the phonon theory of liquid heat capacity, introducing alternative approaches to model low-frequency shear modes. In particular, we consider the recently proposed idea of treating such modes as pure kinetic and we propose a novel approach based on identifying those low-frequency excitations as overdamped liquid-like modes with linear in frequency density of states. Moreover, we complete the theory by incorporating the effects of intramolecular vibrations. By comparing the theoretical predictions from these different approaches with the available data for the heat capacity of several liquids, we present a comprehensive evaluation of the original model and the newly proposed extensions. Despite all approaches perform well at low-temperatures, our results indicate that modeling low-frequency modes as overdamped liquid-like excitations yields the most accurate agreement with the data in the whole temperature range. Conversely, we demonstrate that treating these excitations as purely gas-like leads to significant inaccuracies, particularly at high temperatures.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech)
v1: comments welcome
Critical Current Density and AC Magnetic Susceptibility of High-quality FeTe\(_{0.5}\)Se\(_{0.5}\) Superconducting Tapes
New Submission | Superconductivity (cond-mat.supr-con) | 2025-01-28 20:00 EST
Xin Zhou, Wenjie Li, Qiang Hou, Wei Wei, Wenhui Liu, Ke Wang, Xiangzhuo Xing, Linfei Liu, Jun-Yi Ge, Yanpeng Qi, Huajun Liu, Li Ren, Tsuyoshi Tamegai, Yue Sun, Zhixiang Shi
Iron telluride-selenium superconducting materials, known for their non-toxicity, ease of preparation, simple structure, and high upper critical fields, have attracted much research interest in practical application. In this work, we conducted electrical transport measurements, magneto-optical imaging, and AC magnetic susceptibility measurements on FeTe\(_{0.5}\)Se\(_{0.5}\) superconducting long tapes fabricated via reel-to-reel pulsed laser deposition. Our transport measurements revealed a high critical current density that remains relatively stable even with increasing external magnetic fields, reaching over \(1\times 10^5\) A/cm\(^2\) at 8 K and 9 T. The calculated pinning force density indicates that normal point pinning is the primary mechanism in these tapes. The magneto-optical images demonstrated that the tapes show homogeneous superconductivity and uniform distribution of critical current density. The AC magnetic susceptibility measurements also confirmed their strong flux pinning nature of withstanding high magnetic field. Based on these characteristics, FeTe\(_{0.5}\)Se\(_{0.5}\) superconducting tapes show promising prospects for applications under high magnetic fields.
Superconductivity (cond-mat.supr-con), Strongly Correlated Electrons (cond-mat.str-el)
20 pages, 14 figures
Superconductivity 12 (2024) 100127
Probing non-Gaussian correlations through entanglement generation in a many-body quantum system
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
J. van de Kraats, D.J.M. Ahmed-Braun, V.E. Colussi, S.J.J.M.F. Kokkelmans
In understanding strongly correlated quantum systems, quantifying the non-Gaussian nature of interparticle correlations is invaluable. We show that, for a uniform quantum gas, there exists a natural connection between non-Gaussian correlations and the generation of momentum-space entanglement. Furthermore, this entanglement can be directly measured in an experiment using time-of-flight techniques. To prototype our method, we numerically study entanglement generation in a degenerate Bose gas following a quench to the unitary regime, where Gaussian and non-Gaussian correlations are generated sequentially in time.
Quantum Gases (cond-mat.quant-gas), Quantum Physics (quant-ph)
21 pages, 3+1 figures
Non-Gaussian density fluctuations in the Dean-Kawasaki equation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-01-28 20:00 EST
Computing analytically the \(n\)-point density correlations in systems of interacting particles is a long-standing problem of statistical physics, with a broad range of applications, from the interpretation of scattering experiments in simple liquids, to the quantitative description of the slow and cooperative dynamics in glass formers. For Brownian particles, i.e. with overdamped Langevin dynamics, the microscopic density obeys a stochastic evolution equation, known as the Dean-Kawasaki equation. In spite of the importance of this equation, its complexity makes it very difficult to analyze the statistics of the microscopic density beyond simple Gaussian approximations. In this work, resorting to a path-integral description of the stochastic dynamics and relying on the formalism of macroscopic fluctuation theory, we go beyond the usual linearization of the Dean-Kawasaki equation, and we compute perturbatively the three-point density correlation functions, in the limit of high-density and weak interactions between the particles. This exact result opens the way to using the Dean-Kawasaki beyond the simple Gaussian treatments, and could find applications to understand many fluctuation-related effects in soft and active matter systems.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
Quantum oscillations of holes in GaN
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Chuan F.C. Chang, Joseph E. Dill, Zexuan Zhang, Jie-Cheng Chen, Naomi Pieczulewski, Samuel J. Bader, Oscar Ayala Valenzuela, Scott A. Crooker, Fedor F. Balakirev, Ross D. McDonald, Jimy Encomendero, David A. Muller, Feliciano Giustino, Debdeep Jena, Huili Grace Xing
GaN has emerged to be a major semiconductor akin to silicon due to its revolutionary impacts in solid state lighting, critically enabled by p-type doping, and high-performance radio-frequency and power electronics. Suffering from inefficient hole doping and low hole mobility, quantum oscillations in p-type GaN have not been observed, hindering fundamental studies of valence bands and hole transport in GaN. Here, we present the first observation of quantum oscillations of holes in GaN. Shubnikov-de Haas (SdH) oscillations in hole resistivity are observed in a quantum-confined two-dimensional hole gas at a GaN/AlN interface, where polarization-induced doping overcomes thermal freeze-out, and a sharp and clean interface boosts the hole mobility enough to unmask the quantum oscillations. These holes degenerately occupy the light and heavy hole bands of GaN and have record-high mobilities of ~1900 cm2/Vs and ~400 cm2/Vs at 3K, respectively. We use magnetic fields up to 72 T to resolve SdH oscillations of holes from both valence bands to extract their respective sheet densities, quantum scattering times, and the effective masses of light holes (0.5-0.7 m0) and heavy holes (1.9 m0). SdH oscillations of heavy and light holes in GaN constitute a direct metrology of valence bands and open new venues for quantum engineering in this technologically important semiconductor. Like strained silicon transistors, strain-engineering of the valence bands of GaN is predicted to dramatically improve hole mobilities by reducing the hole effective mass, a proposal that can now be explored experimentally, particularly in a fully fabricated transistor, using quantum oscillations. Furthermore, the findings of this work suggest a blueprint to create 2D hole gases and observe quantum oscillations of holes in related wide bandgap semiconductors such as SiC and ZnO in which such techniques are not yet possible.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
Transition Metal-Driven Variations in Structure, Magnetism, and Photocatalysis of Monoclinic M3Se4 (M = Fe, Co, Ni) Nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Monika Ghalawat, Inderjeet Chauhan, Dinesh Singh, Chinnakonda S. Gopinath, Pankaj Poddar (CSIR-National Chemical Laboratory, Academy of Scientific and Innovative Research)
The transition metal selenides (MxSey) have gained attention for their unique physical and chemical properties, especially those associated with the transition metal (M). Despite advancements in synthesis, fabricating these selenides is challenging due to their complex stoichiometry and high asymmetry. One such system is monoclinic iron selenide (Fe3Se4), which can be used in permanent-magnet technologies and serve as a model system for understanding magnetism. This study focuses on fabricating monoclinic M3Se4 (M = Fe, Co, or Ni) compounds via thermal decomposition, examining how solution chemistry influences their morphology and properties. With a Curie temperature of about 322 K, Fe3Se4 is ferrimagnetic, whereas Co3Se4 and Ni3Se4 are paramagnetic between 5 and 300 K. The latter two compounds also show higher catalytic activity for hydrogen evolution in water splitting, with maximum H2-evolution rates of 1.01, 5.16, and 6.83 mmol h-1g-1 for Fe3Se4, Co3Se4, and Ni3Se4, respectively.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
52 Pages, 20 Figures, 4 Tables including supporting information
Synthesis, crystal structure, site occupancy and magnetic properties of aluminum substituted M-type Sr hexaferrite SrFe12-xAlxO19 nanoparticles
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-01-28 20:00 EST
Matilde Saura-Múzquiz, Anna Zink Eikeland, Marian Stingaciu, Henrik Lyder Andersen, Maxim Avdeev, Mogens Christensen
The synthesis of aluminum substituted strontium hexaferrite nanoparticles (SrFe12-xAlxO19 with x = 0-3), via three different preparation methods, is investigated. The synthesis methods are hydrothermal autoclave (AC) synthesis, a citrate sol-gel (SG) synthesis and a solid-salt matrix (SSM) sol-gel synthesis. Evaluation of macroscopic magnetic properties and of lattice parameters obtained by Rietveld analysis of powder X-ray diffraction (PXRD) data indicate that successful substitution of Al into the crystal structure is only achieved for the SG method. For the SG sample with x = 3, the coercivity was found to increase by 73% to 830 kA/m, while the saturation magnetization was reduced by 68% to 22.6 Am2/kg compared to the non-substituted x = 0 SG sample. The SSM and AC samples did not show any significant changes in their magnetic properties. To examine the nature of the Al insertion in detail, neutron powder diffraction (NPD) data were collected on the SSM and SG samples. Combined Rietveld refinements of the PXRD and NPD data confirm that effective substitution of the Al ions is only achieved for the SG sample and reveal that Al occupies mainly the (2a)Oh and (12k)Oh sites and to a lesser extent the (4e)BP, (4f)Oh and (4f)Td sites. Moreover, the relative degree of site occupation varies with increasing Al substitution. The intrinsic magnetization according to the refined atomic magnetic moments and Al site occupation fractions was extracted from the NPD data and compared with the measured macroscopic magnetization. A remarkable agreement exists between the two, confirming the robustness and accuracy of the Rietveld analysis.
Materials Science (cond-mat.mtrl-sci)
Protecting Intercavity Polaritons in Strongly Coupled Cavities
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-01-28 20:00 EST
Rodrigo Sánchez-Martínez, Yesenia A. García-Jomaso, David Ley-Domínguez, Hugo A. Lara-García, Giuseppe Pirruccio, Arturo Camacho-Guardian
We theoretically designed and experimentally demonstrated a mechanism to protect a spatially segregated mixed light-matter state, known as intercavity exciton-polariton in strongly coupled optical cavities. This excitation, shared across the coupled cavity array, exhibits remarkable robustness over a wide momentum range, without compromising photon-exciton mixing or the spatial separation of its photonic and excitonic components, which also enables a tunable heavy mass. Additionally, we unveil a direct connection between the transparency window, characteristic of slow-light experiments, and the protection of the intercavity polariton nature. Both phenomena originate from the strategic design of an energy-level landscape featuring a \(\Lambda\)-scheme, opening new avenues for exploring and utilizing these unique optical excitations in advanced photonic applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Quantum Gases (cond-mat.quant-gas), Chemical Physics (physics.chem-ph), Optics (physics.optics)
5+2 pages, 5 figures. Comments are welcome
Electric transport as a probe to unveil microscopic aspects of oxygen-depleted YBCO
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-01-28 20:00 EST
C. Acha, A. Camjayi, T. Vaimala, H. Huhtinen, P. Paturi
We report on the characterization of Pt-YBa\(_2\)Cu\(_3\)O\(_{7-\delta}\) interfaces, focusing on how oxygen vacancies content (\(\delta\)) affects electrical transport mechanisms. Our study examines four Pt-YBa\(_2\)Cu\(_3\)O\(_{7-\delta}\) samples with varying \(\delta\) (0.12 \(\leq \delta \leq\) 0.56) using voltage-current measurements across a temperature range. We successfully model the electrical behavior using a Poole-Frenkel conduction framework, revealing that oxygen vacancies create potential wells that trap carriers, directly influencing conduction. We observe that the energy of these traps increases as \(\delta\) rises, in agreement with a peak previously detected in optical conductivity measurements. This result supports earlier interpretations, strengthening the proposed connection between oxygen vacancies and the ionization energy associated with impurity bands in YBa\(_2\)Cu\(_3\)O\(_{7-\delta}\).
Disordered Systems and Neural Networks (cond-mat.dis-nn)
24 pages, 15 figures
Strongly correlated states of transition metal spin defects: the case of an iron impurity in aluminum nitride
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Leon Otis, Yu Jin, Victor Wen-zhe Yu, Siyuan Chen, Laura Gagliardi, Giulia Galli
We investigate the electronic properties of an exemplar transition metal impurity in an insulator, with the goal of accurately describing strongly correlated, defect states. We consider iron in aluminum nitride, a material of interest for hybrid quantum technologies, and we carry out calculations with quantum embedding methods -- density matrix embedding theory (DMET) and quantum defect embedding theory (QDET) and with spin-flip time-dependent density functional theory (TDDFT). We show that both DMET and QDET accurately describe the ground state and low-lying excited states of the defect, and that TDDFT yields photoluminescence spectra in agreement with experiments. In addition, we provide a detailed discussion of the convergence of our results as a function of the active space used in the embedding methods, thus defining a protocol to obtain converged data, directly comparable with experiments.
Strongly Correlated Electrons (cond-mat.str-el)
26 pages, 6 figures
The droplet size distribution and its dynamics in chemically active emulsions
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-01-28 20:00 EST
Jonathan Bauermann, Giacomo Bartolucci, Christoph A. Weber, Frank Jülicher
We present a dynamic theory for the droplet size distribution in chemically active emulsions, considering a simple ternary mixture with a conserved density. We show that the collective behavior of many droplets, such as monodispersity, emerges through a coupling of the conserved density in the far field. Using our theory, we determine the stationary state of such emulsions and characterize the relaxation of the droplet size distributions at late times. A key finding is a universal scaling behavior, leading to the collapse of the rescaled size distributions at late times. Our results suggest that the key features of our dynamic theory are generic and apply to the broader class of multi-component systems with conservation laws and active chemical reactions.
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Twisted gauging and topological sectors in (2+1)d abelian lattice gauge theories
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-01-28 20:00 EST
Bram Vancraeynest-De Cuiper, Clement Delcamp
Given a two-dimensional quantum lattice model with an abelian gauge theory interpretation, we investigate a duality operation that amounts to gauging its invertible 1-form symmetry, followed by gauging the resulting 0-form symmetry in a twisted way via a choice of discrete torsion. Using tensor networks, we introduce explicit lattice realisations of the so-called condensation defects, which are obtained by gauging the 1-form symmetry along submanifolds of spacetime, and employ the same calculus to realise the duality operators. By leveraging these tensor network operators, we compute the non-trivial interplay between symmetry-twisted boundary conditions and charge sectors under the duality operation, enabling us to construct isometries relating the dual Hamiltonians. Whenever a lattice gauge theory is left invariant under the duality operation, we explore the possibility of promoting the self-duality to an internal symmetry. We argue that this results in a symmetry structure that encodes the 2-representations of a 2-group.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
Shift of the Bose-Einstein condensation temperature due to dipolar interactions
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-01-28 20:00 EST
Milan Krstajić, Jiří Kučera, Lucas R. Hofer, Gavin Lamb, Péter Juhász, Robert P. Smith
We report the first measurements of the BEC critical temperature shift due to dipolar interactions, employing samples of ultracold erbium atoms which feature significant (magnetic) dipole-dipole interactions in addition to tuneable contact interactions. Using a highly prolate harmonic trapping potential, we observe a clear dependence of the critical temperature on the orientation of the dipoles relative to the trap axis. Our results are in good agreement with mean-field theory for a range of contact interaction strengths. This work opens the door for further investigations into beyond-mean-field effects and the finite-temperature phase diagram in the more strongly dipolar regime where supersolid and droplet states emerge.
Quantum Gases (cond-mat.quant-gas)
5 pages, 4 figures, supplementary material (5 pages, 2 figures)