CMP Journal 2025-03-06
Statistics
Nature: 1
arXiv: 69
Nature
Sensing ceramides by CYSLTR2 and P2RY6 to aggravate atherosclerosis
Original Paper | Cardiovascular diseases | 2025-03-05 19:00 EST
Siting Zhang, Hui Lin, Jiale Wang, Jingyu Rui, Tengwei Wang, Zeyu Cai, Shenming Huang, Yanxiang Gao, Tianfeng Ma, Rui Fan, Rongbo Dai, Zhiqing Li, Yiting Jia, Qiang Chen, HaoMing He, Jiaai Tan, Shirong Zhu, Rui Gu, Zhigang Dong, Meihong Li, Enmin Xie, Yi Fu, Jingang Zheng, Changtao Jiang, Jinpeng Sun, Wei Kong
Recent evidence shows elevated circulating long-chain ceramide levels predict atherosclerotic cardiovascular disease (ASCVD) independently of cholesterol1,2. Although targeting ceramide signaling may provide therapeutic benefits beyond the treatment of hypercholesterolemia, the underlying mechanism by which circulating ceramides aggravate ASCVD remains elusive. We examined whether circulating long-chain ceramides activate membrane G protein-coupled receptors (GPCRs) to exacerbate atherosclerosis. We performed a systematic screen combining G protein signaling quantification, bioinformatic analysis of GPCRs expression, and functional examination of NLRP3 inflammasome activation, and the results suggested CYSLTR2 and P2RY6 are potential endogenous receptors of C16:0 ceramide-evoked inflammasome activation in both endothelial cells and macrophages. We found that inhibiting CYSLTR2/P2RY6 genetically or pharmacologically alleviated ceramide-induced atherosclerosis aggravation. Additionally, increased ceramide levels correlated with the severity of coronary artery disease in patients with varying degrees of renal impairment. Notably, CYSLTR2/P2RY6 deficiency mitigated chronic kidney disease (CKD)-aggravated atherosclerosis in mice, without affecting cholesterol or ceramide levels. Structural analysis of the ceramide-CYSLTR2-Gq complexes revealed that both C16:0 and C20:0 ceramides bind within an inclined channel-like ligand binding pocket on CYSLTR2. We further revealed an unconventional mechanism underlying ceramides-induced CYSLTR2 activation and CYSLTR2-Gq interface. Overall, our study provided structural and molecular mechanisms that long-chain ceramides initiate transmembrane Gq and inflammasome signaling through directly binding to CYSLTR2 and P2RY6 receptors, and blocking these signaling may provide new therapeutic potential to treat atherosclerosis-related diseases.
Cardiovascular diseases, Cryoelectron microscopy
arXiv
Nitrogen and hydrogen intercalation into crystalline fullerite C$_{60}$ and photoluminescent studies in a wide temperature range
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
V. Zoryansky, P. Zinoviev, Yu. Semerenko
Optical properties of fullerite C$_{60}$ single crystals saturated with hydrogen and nitrogen molecules were studied in the temperature range from 20 K to 230 K using the spectral-luminescent method. Saturation was carried out under a pressure of 30 atm at various temperatures from 470 K to 720 K. At saturation temperatures above 520 K for hydrogen and 690 K for nitrogen, chemical interaction of impurity molecules and the fullerene matrix occurs, forming new chemical compounds. The results of a study of the photoluminescent properties of a new substances are presented for the first time.
Materials Science (cond-mat.mtrl-sci), Other Condensed Matter (cond-mat.other), Atomic and Molecular Clusters (physics.atm-clus), Optics (physics.optics)
13 pages, 4 figures
Gauging non-invertible symmetries on the lattice
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Sahand Seifnashri, Shu-Heng Shao, Xinping Yang
We provide a general prescription for gauging finite non-invertible symmetries in 1+1d lattice Hamiltonian systems. Our primary example is the Rep(D$_8$) fusion category generated by the Kennedy-Tasaki transformation, which is the simplest anomaly-free non-invertible symmetry on a spin chain of qubits. We explicitly compute its lattice F-symbols and illustrate our prescription for a particular (non-maximal) gauging of this symmetry. In our gauging procedure, we introduce two qubits around each link, playing the role of “gauge fields” for the non-invertible symmetry, and impose novel Gauss’s laws. Similar to the Kramers-Wannier transformation for gauging an ordinary $\mathbb{Z}_2$, our gauging can be summarized by a gauging map, which is part of a larger, continuous non-invertible cosine symmetry.
Strongly Correlated Electrons (cond-mat.str-el), High Energy Physics - Theory (hep-th), Quantum Physics (quant-ph)
66 pages, 1 figure, 1 table
Finite-temperature quantum topological order in three dimensions
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Shu-Tong Zhou, Meng Cheng, Tibor Rakovszky, Curt von Keyserlingk, Tyler D. Ellison
We identify a three-dimensional system that exhibits long-range entanglement at sufficiently small but nonzero temperature–it therefore constitutes a quantum topological order at finite temperature. The model of interest is known as the fermionic toric code, a variant of the usual 3D toric code, which admits emergent fermionic point-like excitations. The fermionic toric code, importantly, possesses an anomalous 2-form symmetry, associated with the space-like Wilson loops of the fermionic excitations. We argue that it is this symmetry that imbues low-temperature thermal states with a novel topological order and long-range entanglement. Based on the current classification of three-dimensional topological orders, we expect that the low-temperature thermal states of the fermionic toric code belong to an equilibrium phase of matter that only exists at nonzero temperatures. We conjecture that further examples of topological orders at nonzero temperatures are given by discrete gauge theories with anomalous 2-form symmetries. Our work therefore opens the door to studying quantum topological order at nonzero temperature in physically realistic dimensions.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
5+4 pages, 2 figures
Vestigial Order from an Excitonic Mother State in Kagome Superconductors $A$V$_3$Sb$_5$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Julian Ingham, Ronny Thomale, Harley D. Scammell
Alongside high-temperature charge order and superconductivity, kagome metals exhibit signatures of time-reversal symmetry breaking and nematicity which appear to depend strongly on external perturbations such as strain and magnetic fields, posing a fundamental challenge for conceptual reconciliation. We develop a theory of vestigial order descending from an excitonic mother state in $A$V$_3$Sb$5$ ($A$=K,Rb,Cs), which develops around $T\ast \approx 40$ K. The application of external fields stabilises a subset of the phase-melted order parameter manifold, referred to as a vestigial state, producing a symmetry-breaking response which depends on the applied probe. Our theory reproduces the observations of piezomagnetism, electric magnetic chiral anisotropy, absence of Kerr rotation, unusual elastoresistance response, and superconducting diode effect. Our proposed excitonic mother state accounts for probe-dependent symmetry breaking patterns without fine-tuning, and predicts additional signatures accessible through optical spectroscopy.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con), Quantum Physics (quant-ph)
6+3 pages, 3 figures
Quantum oscillation studies of the nodal line semimetal Ni3In2S2-xSex
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
M. M. Sharma, Santosh Karki Chhetri, Gokul Acharya, David Graf, Dinesh Upreti, Sagar Dahal, Md Rafique Un Nabi, Sumaya Rahman, Josh Sakon, Hugh O. H. Churchill, Jin Hu
Ternary shandite compounds with the general formula T3M2X2 (T = Ni, Co, Rh or Pd; M = Sn, In or Pb and X = S or Se) have emerged as a large pool of topological semimetals. This family of compounds hosts different topological phases for various combinations of T, M and X. This paper reports the observation of quantum oscillations under the high magnetic fields in Ni3In2S2-xSex single crystals. Angular dependence of oscillation frequency suggests an evolution of the Fermi surface from three-dimensional to two-dimensional on Se substitution for S in Ni3In2S2. The effective mass obtained for each composition by fitting the oscillation amplitude with the Lifshitz-Kosevich formula, shows no significant change, suggesting that the topological phase might be relatively robust against enhanced SOC upon Se doping in Ni3In2S2.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
23 pages, 6 figures
Acta Materialia 289, 120884 (2025)
Configurational Information Measures, Phase Transitions, and an Upper Bound on Complexity
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
Damian R Sowinski, Sean Kelty, Gourab Ghoshal
Configurational entropy (CE) and configurational complexity (CC) are recently popularized information theoretic measures used to study the stability of solitons. This paper examines their behavior for 2D and 3D lattice Ising Models, where the quasi-stability of fluctuating domains is controlled by proximity to the critical temperature. Scaling analysis lends support to an unproven conjecture that these configurational information measures (CIMs) can detect (in)stability in field theories. The primary results herein are the derivation of a model dependent CC-CE relationship, as well as a model independent upper bound on CC. CIM phenomenology in the Ising universality class reveals multiple avenues for future research.
Statistical Mechanics (cond-mat.stat-mech), Information Theory (cs.IT), Mathematical Physics (math-ph), Adaptation and Self-Organizing Systems (nlin.AO), Pattern Formation and Solitons (nlin.PS)
9 pages, 2 appendices, 3 figures
Transmissions and group delay time in graphene with proximity exchange field and double barriers
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Ahmed Jellal, Rachid El Aitouni, Pablo Díaz, David Laroze
We study the transmission and group delay time for fermions in graphene under a proximity exchange field scattered by double barriers. Solving the Dirac equation over five regions, we calculate transmission and reflection coefficients using the transfer matrix method, and analyze group delay time using a Gaussian wave packet and the stationary phase method. Our results reveal spin-dependent features in transmission and group delay time, with notable shifts between spin orientations, especially for configurations with up to three layers of boron nitride (BN). We observe enhanced Klein tunneling peaks and full transmission conditions for certain combinations of system parameters. The double-barrier configuration also significantly improves the group delay time compared to the single-barrier case. In fact, we show that the group delay time oscillates as the barrier width increases without showing signs of saturation, indicating the absence of the Hartman effect. This is in contrast to the single-barrier case, where the group delay time is found to saturate as the barrier width increases. In addition, we identify critical angles and maximum energies for evanescent modes.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
11 pages, 5 figures. Version to appear in Physica Scripta 2015
Self-sustained frictional cooling in active matter
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Alexander P. Antonov, Marco Musacchio, Hartmut Löwen, Lorenzo Caprini
Cooling processes in nature are typically generated by external contact with a cold reservoir or bath. According to the laws of thermodynamics, the final temperature of a system is determined by the temperature of the environment. Here, we report a spontaneous internal cooling phenomenon for active particles, occurring without external contact. This effect, termed ``self-sustained frictional cooling’’, arises from the interplay between activity and dry (Coulomb) friction, and in addition is self-sustained from particles densely caged by their neighbors. If an active particle moves in its cage, dry friction will stop any further motion after a collision with a neighbor particle thus cooling the particle down to an extremely low temperature. We demonstrate and verify this self-sustained cooling through experiments and simulations on active granular robots and identify dense frictional arrested clusters coexisting with hot, dilute regions. Our findings offer potential applications in two-dimensional swarm robotics, where activity and dry friction can serve as externally tunable mechanisms to regulate the swarm’s dynamical and structural properties.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Laser-assisted tunneling and Hartman effect in graphene under scalar potential and exchange fields
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Rachid El Aitouni, Ahmed Jellal, Pablo Díaz, David Laroze
We study the tunneling effect of Dirac fermions in a graphene sheet by introducing a potential barrier in a region of width $D$ exposed to laser field. This sheet is placed on a boron nitride/ferromagnetic substrate such as cobalt or nickel. By using the Floquet theory, we determine the solutions of the energy spectrum. We calculate the transmission and reflection coefficients by applying the boundary conditions along with the transfer matrix method. These coefficients help determine their probabilities by current densities and group delay times by their phases. We numerically show that the laser field plays a crucial role in this structure, as it completely suppresses Klein tunneling compared to the case without laser. Furthermore, in contrast to the Hartman effect, the group delay time becomes dependent on the barrier width with the appearance of additional peaks. This suggests that fermion-field interactions cause additional delays within the barrier and also help to reduce spin coupling. Adding BN layers increases the interval of transmission suppression and completely eliminates coupling after the addition of three BN layers. Total reflection is observed for incident fermions with an angle less than $-1$ or greater than one.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
13 pages, 7 figures. Version to appear in Physica E 2025
Collective neutral excitations as sensitive probe for the quality of 2D charge carrier systems in ultra-pure GaAs quantum wells
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Ursula Wurstbauer, Michael J. Manfra, Ken W. West, Loren N. Pfeiffer
Ultra-clean low-dimensional interacting charge carrier systems are the basis to explore correlated states and phases. We report the observation of very narrow collective intersubband excitations (ISBE) of 2D electron systems (2DESs) with ultra-high mobilities in high quality GaAs quantum well structures. These findings from resonant inelastic light scattering (RILS) experiments are used as tools for exploration of links between transport mobility and collective electron behavior in 2DES of high perfection. We find that the linewidths of collective ISBE modes can be very narrow with values smaller than 80{\mu}eV. Comparison of ISBE measurements from several high-mobility samples exhibits a variation in linewidth of more than a factor of two. There is, however, a surprising lack of direct correlation between ISBE linewidth with mobility in the range 15x10^6 cm^2/Vs<{\mu}<24x10^6 cm^2/Vs. ISBE by RILS are discussed as a sensitive probe to characterize the interacting electron systems for fractional quantum Hall effect (FQHE) studies.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
accepted for publication in solid state communications as part of the “memorial issue in honor of Aron Pinczuk”
Twisting in h-BN bilayers and their angle-dependent properties
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Diem Thi-Xuan Dang, Dai-Nam Le, Lilia M. Woods
In this paper, we systematically investigate the structural and electronic properties of twisted h-BN bilayers to understand the role of the twisting angle. Using first-principles methods with relaxation taken into account, we simulate h-BN bilayers with commensurate supercells with the smallest angle being $2.88^{\circ}$ until $60^{\circ}$. We find that the interlayer separation is not constant throughout each bilayer because of the various stacking patterns of AA, AA’, AB, AB’, and A’B throughout the layers, which also play a significant role in their unique charge redistribution. The calculations for the 110 generated structures show the existence of flat bands in several twisted h-BN bilayers, as well as the emergence of different trends in their properties as a function of the twist angle. These results are useful for establishing a systematic base line of registry-dependent relations for the development of more advanced computational methods to access incommensurate h-BN bilayers.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
9 pages, 6 figures, submitted
State-dependent friction for a moving liquid contact line over rough solid surfaces
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Caishan Yan, Penger Tong, Qin Xu
Solid friction between two rough surfaces is often observed to increase logarithmically over time due to contact creeping. An intriguing question is whether a similar aging effect occurs in contact line (CL) friction over rough substrates. Here, we report a systematic experimental study of CL friction using a hanging-fiber atomic force microscope (AFM) to measure the frictional force as a liquid CL moves across a fiber surface with different coatings under a well-controlled time protocol. State- (or time-)dependent CL friction is observed for the fiber surface with different textures in both the advancing and receding directions. The experimental findings are explained by a phenomenological model that links mesoscale CL friction to the microscopic relaxation of metastable air bubbles or liquid droplets trapped in the interstices of a rough surface. This model offers a general aging mechanism relevant to a wide range of liquid-solid interfaces.
Soft Condensed Matter (cond-mat.soft)
Linking quantum mechanical features to structural phase-transformation in inorganic solids
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Prashant Singh, Anis Biswas, Alexander Thayer, Yaroslav Mudryk
We present a new descriptor, i.e., local lattice distortion, to predict structural phase transformation in inorganic compounds containing lanthanides and transition metals. The descriptor utilizes local lattice and angular distortions obtained from structural optimization of experimentally known crystalline phases within state-of-the-art density-functional theory method. The predictive power of the descriptor was tested on lanthanide based RE2In (RE=rare-earth) compounds known for a variety of phase transformations. We show that the inclusion of quantum-mechanical effects through local-charge, bonding, symmetry, and electronic-structure enhances the robustness of the descriptor in predicting structural phase transformation. To gain further insights, we analyzed phononic and electronic behavior of Y2In, and show that experimentally observed phase transformation can only be predicted when atomic strains are included. The descriptor was used to predict structural phase change in couple of new compounds, i.e., (Yb1-xErx)2In and Gd2(In1-xAlx), which was validated by X-ray powder diffraction measurements. Finally, we demonstrated the generality of the proposed descriptor by predicting phase transformation behavior in different classes of compounds indicating the usefulness of our approach in mapping desired phase changes in novel functional materials.
Materials Science (cond-mat.mtrl-sci)
25 page, 8 figures, 78 references
Quantum Geometric Engineering of Dual Hall Effects in 2D Antiferromagnetic Bilayers via Interlayer Magnetic Coupling
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Zhenning Sun, Tao Wang, Hao Jin, Xinru Li, Yadong Wei, Jian Wang
The interplay between quantum geometry and magnetic order offers a novel strategy for designing next-generation nanodevices. Here, we demonstrate that interlayer magnetic coupling in two-dimensional (2D) CoPSe3 bilayers enables precise control over quantum geometric mechanisms, unlocking dual intrinsic Hall effects. Our first-principles calculations reveal that the altermagnetic (AM) phase exhibits a giant anisotropic anomalous Hall effect (AHE) ($\sigma_{xy}$ is approximately 46 S/cm) driven by Berry curvature localized at generic k-points, while the PT-symmetric antiferromagnetic (AFM) phase hosts an intrinsic second-order nonlinear anomalous Hall effect (NAHE) ($\chi_{xyy}$ is approximately 160 ${\mu}$S/V) originating from quantum metric accumulation at high-symmetry k-points. By tuning interlayer magnetic couplings, we achieve reversible switching between these phases, leveraging their distinct band structures and symmetry constraints. The Neel-vector-dependent AHE in the AM phase and the symmetry-protected NAHE in the AFM phase highlight quantum geometry as a versatile tool for manipulating transport properties. Our work establishes 2D antiferromagnets as a promising platform for multifunctional device architectures, bridging linear and nonlinear magnetoelectric responses through tailored quantum geometric engineering.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci)
Observation of giant nonlinear valley Hall effect
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Pan He, Min Zhang, Jin Cao, Jingru Li, Hao Liu, Jinfeng Zhai, Ruibo Wang, Cong Xiao, Shengyuan A. Yang, Jian Shen
The valley Hall effect (VHE) holds great promise for valleytronic applications by leveraging the valley degree of freedom. To date, research on VHE has focused on its linear response to an applied current, leaving nonlinear valley responses undetected and nonlinear valleytronic devices undeveloped. Here, we report the experimental observation of a nonlinear VHE in a graphene-hBN moire superlattice, evidenced by the generation of second-harmonic nonlocal voltages under AC currents. Remarkably, the nonlinear VHE has magnitude surpassing the linear VHE and is highly tunable via a gate voltage, which exhibits a pair of opposite peaks on the two sides of a Dirac gap. The nonlinear signal shows quadratic scaling with driving current and quartic scaling with local resistance, setting it apart from the linear counterpart. These experimental features are consistent with the theoretical picture of nonlocal transport mediated by nonlinear VHE and linear inverse VHE. We further reveal a nonlinear inverse VHE by observing the third- and fourth-harmonic nonlocal voltages. The nonlinear VHE provides a novel mechanism for valley manipulation and enables a novel valleytronic device, the valley rectifier, that converts AC charge current into DC valley current.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Glassy Behavior and Anomalous Transport in Chimney Ladder Crystals Induced by Soft Optical Phonons
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Srinivas V. Mandyam, Weicen Dong, Xiaoxian Yan, Binru Zhao, Junfa Lin, Tianlong Xia, Zhiying Zhao, Xi Chen, Jie Ma, Hui Xing, F. Malte Grosche, Matteo Baggioli
Nowotny chimney ladder (NCL) crystals present physical properties in between the contrasting paradigms of ideal crystal and amorphous solid, making them promising candidates for thermoelectric applications due to their inherently low thermal conductivity. Here, we report an extensive experimental characterization of the thermodynamic and thermoelectric transport properties of a large class of NCL materials, focusing on the intermetallic compound Ru$2$Sn${3-\delta}$. We show that the heat capacity of these NCL compounds exhibits a boson-peak-like glassy anomaly between $8$ K and $14$ K. By combining experimental measurements with density functional theory (DFT), we attribute its microscopic origin to extremely soft optical phonons that universally appear as a consequence of the chimney ladder sublattice structure. Additionally, the measured thermal conductivity and the thermoelectric response present distinct anomalous glass-like features that strongly correlate with the dynamics of the abundant soft optical phonons revealed by DFT. Our work demonstrates that soft modes in ordered crystals can induce glassy behavior, outlining a pathway to design metallic materials with low thermal conductivity and unique thermoelectric properties without the need for disorder or strong electronic correlations.
Materials Science (cond-mat.mtrl-sci), Soft Condensed Matter (cond-mat.soft)
v1: comments welcome; animation videos attached
Noise-induced cycles in the Togashi-Kaneko model with species-dependent degradation
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
Jeremy R. Worsfold, Richard G. Morris
The two-state Togashi-Kaneko model demonstrates how, at finite system sizes, autocatalysis can lead to noise-induced bistability between different molecular species. By allowing the export rates to be species-dependent, we find that the nascent stochastic switching between molecular species is coupled to periods of growth or decay in the system size, $N$, leading to a type of noise-induced cycle. Since there is no oscillatory behavior in the underlying deterministic dynamics, this behavior is distinct from other types of noisy cycle. By combining piecewise-deterministic-Markov and linear-noise approximations, we find analytic expressions for the stationary distributions of the different molecular species when stochastic switching is faster than molecular import or export. We envisage that other models in the voter class – including spin systems, flocking and opinion dynamics – will also exhibit noise-induced cycles, as well as be amenable to similar techniques.
Statistical Mechanics (cond-mat.stat-mech)
12 pages, 5 figures
Vortex Motion Induced Losses in Tantalum Resonators
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Faranak Bahrami, Matthew P. Bland, Nana Shumiya, Ray D. Chang, Elizabeth Hedrick, Russell A. McLellan, Kevin D. Crowley, Aveek Dutta, Logan Bishop-Van Horn, Yusuke Iguchi, Aswin Kumar Anbalagan, Guangming Cheng, Chen Yang, Nan Yao, Andrew L. Walter, Andi M. Barbour, Sarang Gopalakrishnan, Robert J. Cava, Andrew A. Houck, Nathalie P. de Leon
Tantalum (Ta) based superconducting circuits have been demonstrated to enable record qubit coherence times and quality factors, motivating a careful study of the microscopic origin of the remaining losses that limit their performance. We have recently shown that the losses in Ta-based resonators are dominated by two-level systems (TLSs) at low microwave powers and millikelvin temperatures. We also observe that some devices exhibit loss that is exponentially activated at a lower temperature inconsistent with the superconducting critical temperature (Tc) of the constituent film. Specifically, dc resistivity measurements show a Tc of over 4 K, while microwave measurements of resonators fabricated from these films show losses that increase exponentially with temperature with an activation energy as low as 0.3 K. Here, we present a comparative study of the structural and thermodynamic properties of Ta-based resonators and identify vortex motion-induced loss as the source of thermally activated microwave loss. Through careful magnetoresistance and x-ray diffraction measurements, we observe that the increased loss occurs for films that are in the clean limit, where the superconducting coherence length is shorter than the mean free path. Vortex motion-induced losses are suppressed for films in the dirty limit, which show evidence of structural defects that can pin vortices. We verify this hypothesis by explicitly pinning vortices via patterning and find that we can suppress the loss by microfabrication.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci), Quantum Physics (quant-ph)
Structural, vibrational, and transport properties of compound forming liquid Li-Bi alloys
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
S.G. Khambholja, A. Abhishek, B.Y. Thakore
Due to the compound forming tendency, some of the liquid metal alloys show anomalous behavior in their physical and chemical properties. Near the compound forming concentration, their electrical resistivity is beyond the metallic values and hence they may be labelled as liquid semiconductors. Lithium-Bismuth is one such system. It shows some interesting features in terms of physical and chemical properties such as departure from nearly free electron theory, very high value of electrical resistivity near the compound forming composition. While dealing with the electrical resistivity of liquid alloys with very high values of electrical resistivity, the famously used approaches such as Faber-Ziman theory and Morgan theory have some limitations. Hence, some modifications in these theoretical formalisms are required in order to reproduce the experimental values of the electrical transport properties. We, in the present work have modeled liquid Li-Bi system using model potential formalism in conjunction with the established theoretical models along with suitable modifications to study structural, elastic and transport properties. In particular, we have treated the effective valence of pure Li and Bi as parameters and we have calculated the phase shifts using model potentials rather than muffin-tin potential. The results are compared with the results of molecular dynamics simulation and other theoretical models. It is observed that the t-matrix formulation in conjunction with the model potential formalism is able to reproduce the correct trends in the electrical resistivity isotherm. Whereas the results of Faber-Ziman and Morgan theory are highly underestimated, the non-metallic behavior near the critical composition can be explained clearly from the present results of electrical resistivity. Further, phonon frequencies and sound velocities are also estimated.
Materials Science (cond-mat.mtrl-sci)
Large Spin Hall Effect in High-Entropy Alloy/CoFeB Bilayers
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Takahide Kubota, Kazuya Z. Suzuki, Yoshiyuki Hirayama, Shigeki Takahashi, Koki Takanashi
High-entropy alloys (HEAs) exhibit various physical properties, such as high microhardness for structured materials and high efficiency for catalysis. These features are recognized as a cocktail effect of five or more elements that stabilize a single-phase solid solution due to a high configurational entropy. HEAs may also exhibit short-range orders and microdistorshons, which cause the local symmetry breaking of systems. Systems with local symmetry breaking are of interest for spin-dependent transport, such as for spin Hall effects. In this study, sputtered-film samples of an HEA, Mn–Nb–Mo–Ta–W, and related alloys, were fabricated; these films were layered with ferromagnetic CoFeB. All samples exhibited x-ray diffraction peaks originating only from a body-centered cubic (bcc) phase, and transmission electron microscopy images indicated the absence of secondary phases and uniform elemental distributions. The spin Hall magnetoresistance (SMR) was investigated, and clear resistance changes were observed in all the samples. Quantitative analysis of SMR revealed that the spin Hall angle ($\theta_\mathrm{SH}$) was 0.12 $\pm$ 0.002 and 0.14 $\pm$ 0.037 for the HEA and Nb–Mo–Ta–W alloy (medium-entropy alloy (MEA)), respectively. The $\theta_\mathrm{SH}$s of the HEA and MEA were comparable to that of Pt which is a typical heavy element with relatively large $\theta_\mathrm{SH}$. The newly developed HEA and MEA films are attractive spin Hall materials with the bcc phase and are suitable for spintronic applications using magnetic tunnel junctions with CoFeB and an MgO barrier.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Molecular-dynamics study of diffusional creep in uranium mononitride
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Mohamed AbdulHameed, Benjamin Beeler, Conor O.T. Galvin, Michael W.D. Cooper, Nermeen Elamrawy, Antoine Claisse
Uranium mononitride (UN) is a promising advanced nuclear fuel due to its high thermal conductivity and high fissile density. Yet, many aspects of its mechanical behavior and microstructural features are currently unknown. In this paper, molecular dynamics (MD) simulations are used to study UN’s diffusional creep. Nanometer-sized polycrystals are used to simulate diffusional creep and to calculate an effective GB width. It is found that Nabarro-Herring creep is not dominant in the temperature range of 1700$-$2000 K and that the dominant diffusional creep mechanism is Coble creep with an activation energy of 2.28 $\pm$ 0.09 eV. A method is proposed to calculate the diffusional GB width and its temperature dependence in polycrystals. The effective GB width of UN is calculated as 2.69 $\pm$ 0.08 nm. This value fits very well with the prefactor of the phenomenological Coble creep formula. It is demonstrated that the most comprehensive thermal creep model for UN can be represented as the combination of our Coble creep model and the dislocation creep model proposed by Hayes et al.
Materials Science (cond-mat.mtrl-sci)
Dynamics of stiff filaments in size-polydisperse hard sphere fluids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Thokchom Premkumar Meitei, Lenin S. Shagolsem
The dynamics of a stiff filament (made by connecting beads) embedded in size-polydisperse hard sphere fluid is investigated by means of molecular dynamics simulations with focus on how the degree of size-polydispersity, characterized by polydispersity index ($\delta$), affects the dynamics in this model heterogeneous system. Polydispersity of the fluid as well as strong coupling of rotational and translational motion of the rods are two of the various hurdles in interpreting the experimental results in a complex fluid environment. Furthermore, influence of volume fraction, $\phi$, and absolute free volume, $V_{\rm free}$, which changes inherently with $\delta$ on the dynamics are not adequately discussed in the literature. Thus, we investigate the dynamical behaviour of the rods under two different conditions: (i) constant pressure (in which $\phi$ changes with $\delta$), and (ii) constant $\phi$. Under constant pressure it is observed that the rotational relaxation time and hence the diffusion constant, $D_R$, varies with rod length as $D_R \sim l^{-\alpha}$, where the value of exponent $\alpha$ increases from $3.0-3.2$ while varying $\delta$ from $0-40%$. It is observed that the effect of increasing $\phi$ dominates over the effect of increasing $V_{\rm free}$. Also there is minimal effect of hydrodynamic interaction among the beads belonging to a rod during rotation, whereas the presence of partial hydrodynamic screening for the motion of the centre of mass is seen. On the other hand, for fixed $\phi$ systems, increasing $\delta$ results in increasing $V_{\rm free}$ and thus enhances tracer diffusion, an opposite trend compared to the system under constant pressure.
Soft Condensed Matter (cond-mat.soft)
10 pages, 10 figures
Universal law for the dispersal of motile microorganisms in porous media
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
T. Pietrangeli, R. Foffi, R. Stocker, C. Ybert, C. Cottin-Bizonne, F. Detcheverry
Dispersal is essential to the plethora of motile microorganisms living in porous environments, yet how it relates to movement patterns and pore space structure remains largely unknown. Here we investigate numerically the long-time dispersal of a run-and-tumble microorganism that remains trapped at solid surfaces and escapes from them by tumbling. We find that dispersal and mean run time are connected by a universal relation, that applies for a variety of porous microstructures and swimming strategies. We explain how this generic dependence originates in the invariance of the mean free path with respect to the movement pattern, and we discuss the optimal strategy that maximizes dispersal. Finally, we extend our approach to microorganisms moving along the surface. Our results provide a general framework to quantify dispersal that works across the vast diversity of movement patterns and porous media.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
Pressure-driven superconductivity in the topological insulator GeBi4Te7
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Yalei Huang, Na Zuo, Zheyi Zhang, Chunqiang Xu, Xiangzhuo Xing, Wen-He Jiao, Bin Li, Wei Zhou, Xiaobing Liu, Dong Qian, Xiaofeng Xu
The van der Waals, pseudo-binary chalcogenides (ACh)m(Pn2Ch3)n (A = Ge, Mn, Pb, etc.; Pn = Sb or Bi; Ch = Te, Se) have recently been reported to host a vast landscape of topological phases of matter, including the quantum anomalous Hall state and topological axion state with quantized magnetoelectric effect. A subgroup in this series, like MnSb4Te7 and GeSb4Te7, can be driven to a superconducting state by applying a physical pressure, making them viable candidates to realize so-called topological superconductivity. However, the role of magnetic fluctuations in this pressure-induced superconductivity remains unclear. Here, we report the pressure-induced multiple superconducting phases in the nonmagnetic GeBi4Te7, accompanied by corresponding structural transitions evidenced from the high-pressure Raman scattering. In comparison with other members in this family, we find the superconducting transition temperature of the nonmagnetic subgroup is significantly higher than their magnetic homologues, possibly hinting at the detrimental role played by the magnetic fluctuations in the superconductivity formation, at least in this pseudo-binary chalcogenide family.
Superconductivity (cond-mat.supr-con)
Interfacial spin-orbit-coupling-induced strong spin-to-charge conversion at an all-oxide ferromagnetic /quasi-two-dimensional electron gas interface
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Mi-Jin Jin, Guang Yang, Doo-Seung Um, Jacob Linder, Jason W.A. Robinson
Functional oxides and hybrid structures with interfacial spin orbit coupling and the Rashba-Edelsterin effect (REE) are promising materials systems for thermal tolerance spintronic device applications. Here, we demonstrate efficient spin-to-charge conversion through enhanced interfacial spin orbit coupling at the all-oxide interface of La1-xCaxMnO3 with quasi-two-dimensional (quasi-2D) SrTiO3 (LCMO/STO). The quasi-2D interface is generated via oxygen vacancies at the STO surface. We obtain a spin-to-charge conversion efficiency of ~ 2.32 +- 1.3 nm, most likely originating from the inverse REE, which is relatively large versus all-metallic spin-to-charge conversion materials systems. The results highlight that the LCMO/STO 2D electron gas is a potential platform for spin-based memory and transistor applications.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
12pages, 4 figures
Low-temperature structural study of smectic C$_A$* glass by X-ray diffraction
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Aleksandra Deptuch, Marcin Kozieł, Marcin Piwowarczyk, Magdalena Urbańska, Ewa Juszyńska-Gałązka
The liquid crystalline compound, forming the glass of the smectic C$_A$\ast phase, is investigated by the X-ray diffraction in the 18-298 K range. The characteristic distances within the smectic C$_A$\ast phase are determined. The electron density profile along the smectic layer normal is inferred and compared with the results of the density functional theory calculations. Observations of the selective reflection of the visible light investigate the helical ordering within the smectic C$_A$\ast glass. The results indicate slow evolution of the smectic layer spacing, intermolecular distances, and electron density distribution below the glass transition temperature. Meanwhile, the relative range of the short-range order within the smectic layers and the helix pitch are relatively constant in the glassy state.
Soft Condensed Matter (cond-mat.soft)
Unconventional topological edge states in one-dimensional gapless systems stemming from nonisolated hypersurface singularities
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Hongwei Jia, Jing Hu, Ruo-Yang Zhang, Yixin Xiao, Dongyang Wang, Mudi Wang, Shaojie Ma, Xiaoping Ouyang, Yifei Zhu, C. T. Chan
Topologically protected edge states have been extensively studied in systems characterized by the topological invariants in band gaps (also called line gaps). In this study, we unveil a whole new form of edge states that transcends the established paradigms of band-gap topology. In contrast to the traditional stable edge states in topological insulators with specific band gaps, the one-dimensional systems we investigate are inherently gapless with the Brillouin zones being mapped to the loops encircling hypersurface singularities in a higher-dimensional space with parity-time symmetry. These hypersurface singularities are nonisolated degeneracies embedded entirely on exceptional surfaces, rendering the energy gaps in our systems inevitably closed at the intersections of the Brillouin zone loop and the exceptional surfaces. Unexpectedly, such gapless systems still afford topologically protected edge states at system boundaries, challenging the conventional understanding based on band gaps. To elucidate the existence of these edge states in the absence of a band-gap-based invariant, we propose a theoretical framework based on eigen-frame rotation and deformation that incorporates non-Bloch band theory. Finally, we experimentally demonstrate this new form of topological edge states with nonreciprocal circuits for the first time. Our work constitutes a major advance that extends topological edge states from gapped phases to gapless phases, offering new insights into topological phenomena.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Polydispersity-driven dynamical differences between two- and three-dimensional supercooled liquids
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Ilian Pihlajamaa, Lotte van Gessel, Corentin Laudicina, Luc van Burik, Liesbeth Janssen
Previous studies have suggested a conundrum in the relaxation dynamics of polydisperse supercooled liquids. It has been shown that in two dimensions, the relative relaxation times of particles of different sizes become more similar as the material is cooled, whereas the opposite happens in three dimensions: they decouple. Here we resolve this conundrum. First, we show that the coupling observed in two dimensions is an artifact of cage correction introduced to account for Mermin-Wagner fluctuations. Instead, the relative relaxation time of small and large particles in two dimensions remains constant or slightly decouples with temperature, as opposed to the substantial decoupling observed in three dimensions. Investigating these dimensional differences further, we find through mobile cluster analysis that small particles initiate relaxation in both dimensions. As the clusters grow larger, they remain dominated by small particles in three dimensions whereas in two cluster growth becomes particle-size agnostic. We explain these findings with a minimal model by studying the distributions of single-particle barrier heights in the system, showing there is a clear difference in the environments of small and large particles, depending on the dimensionality. These findings highlight the critical role of dimensionality in glass formation, providing new insights into the mechanisms underlying the glass transition in polydisperse supercooled liquids.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci), Statistical Mechanics (cond-mat.stat-mech), Chemical Physics (physics.chem-ph)
Momentum-Resolved Signatures of Carrier Screening Effects on Electron-Phonon Coupling in MoS$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Yiming Pan, Patrick-Nigel Hildebrandt, Daniela Zahn, Marios Zacharias, Yoav William Windsor, Ralph Ernstorfer, Fabio Caruso, Hélène Seiler
Electron-phonon coupling is central to many condensed matter phenomena. Harnessing these effects for novel material functionality in materials always involves non-equilibrium electronic states, which in turn alter quasi-free-carrier density and screening. Thus, gaining a fundamental understanding of the interplay of carrier screening and electron-phonon coupling is essential for advancing ultrafast science. Prior works have mainly focused on the impact of carrier screening on electronic structure properties. Here we investigate the non-equilibrium lattice dynamics of MoS2 after a photoinduced Mott transition. The experimental data are closely reproduced by ab-initio ultrafast dynamics simulations. We find that the non-thermal diffuse scattering signals in the vicinity of the Bragg peaks, originating from long-wavelength phonon emission, can only be reproduced upon explicitly accounting for the screening of electron-phonon interaction introduced by the Mott transition. These results indicate the screening influences electron-phonon coupling, leading to a suppression of intravalley phonon-assisted carrier relaxation. Overall, the combined experimental and computational approach introduced here offers new prospects for exploring the influence of screening of the electron-phonon interactions and relaxation pathways in driven solids.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Gate-tunable band-edge in few-layer MoS$_2$
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Michele Masseroni, Isaac Soltero, James G. Hugh, Igor Rozhansky, Xue Li, Alexander Schmidhuber, Markus Niese, Takashi Taniguchi, Kenji Watanabe, Vladimir Fal’ko, Thomas Ihn, Klaus Ensslin
Transition metal dichalcogenides (TMDs) have garnered significant research interest due to the variation in band-edge locations within the hexagonal Brillouin zone between single-layer and bulk configurations. In monolayers, the conduction band minima are centered at the $K$-points, whereas in multilayers, they shift to the $Q$-points, midway between the $\Gamma$ and $K$ points. In this study, we conduct magnetotransport experiments to measure the occupation in the $Q$ and $K$ valleys in fourlayer molybdenum disulfide (MoS$_2$). We demonstrate electrostatic tunability of the conduction band edge by combining our experimental results with a hybrid $k\cdot p$ tight-binding model that accounts for interlayer screening effects in a self-consistent manner. Furthermore, we extend our model to bilayer and trilayer MoS$_2$, reconciling prior experimental results and quantifying the tunable range of band edges in atomically thin TMDs.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Other Condensed Matter (cond-mat.other)
Interaction induced reentrance of Bose glass and quench dynamics of Bose gases in twisted bilayer and quasicrystal optical lattices
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-06 20:00 EST
Shi-Hao Ding, Li-Jun Lang, Qizhong Zhu, Liang He
We investigate the ground state and dynamical properties of ultracold gases in optical lattices with an aperiodic external potential-a scenario motivated by recent experiments on twisted bilayer optical lattices and optical quasicrystals. Our study reveals that the interplay between on-site repulsive interactions and a quasiperiodic potential gives rise to rich physics. At low filling factors, increasing the interaction strength induces a delocalization effect that transforms a Bose glass (BG) phase, characterized by disconnected superfluid (SF) regions, into a SF phase with a percolated network of SF clusters. This transition is quantitatively characterized by monitoring the percolation probability. At higher filling factors, we uncover a reentrant behavior: as the on-site interaction increases, the system initially transitions from BG to SF, but further increase restores the BG phase. This reentrance is ascribed to an interaction-driven rearrangement of particles, where a once percolated SF network fragments into isolated SF islands as repulsive interactions dominate. Furthermore, our analysis of quench dynamics demonstrates distinct transient behaviors. Intra-phase quenches yield minimal variations in both the percolation probability and the inverse participation ratio (IPR) of the particle density distribution. In contrast, inter-phase quenches produce pronounced effects; for instance, a quench from the SF to BG phase is marked by an abrupt loss of global SF connectivity, while a BG-to-SF quench features oscillatory changes in the percolation probability and a gradual decrease in the IPR, eventually stabilizing the SF phase. Our findings unveil the complex interplay between disorder and interaction in ultracold Bose gases, offering valuable insights that are highly pertinent to current experimental efforts employing twisted bilayer and quasicrystalline optical lattice platforms.
Quantum Gases (cond-mat.quant-gas), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 4 figures
Magneto-rotation coupling for ferromagnetic nanoelement embedded in elastic substrate
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Grzegorz Centała, Jarosław W. Kłos
This study investigates magneto-rotational coupling as a distinct contribution to magnetoelastic interactions, which can be influenced by magnetic anisotropy. We determine magneto-rotational coupling coefficients that incorporate the shape anisotropy of a magnetic nanoelement (strip) and demonstrate that this type of coupling can be modified through geometric adjustments. Furthermore, we analyze the magneto-rotational contribution to the magnetoelastic field in a ferromagnetic strip embedded in a nonmagnetic substrate. Both Rayleigh and Love waves are considered sources of the magnetoelastic field, and we examine how the strength of the magneto-rotational coupling varies with the direction of the in-plane applied magnetic field. We found that in the absence of magnetocrystalline anisotropy the magneto-rotational contribution to the magnetoelastic field decreases with a reduction in the thickness-to-width ratio of the strip for a Rayleigh wave, whereas for a Love wave, it changes non-monotonically. These findings enhance the understanding of magneto-rotational coupling in magnonic nanostructures.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Lattice dynamics of hexagonal ZnMgS
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Abdelmahjid Elmahjoubi, Mala Rao, Alexandre Ivanov, Andrei Postnikov, Alain Polian, Toni Alhaddad, Samrath Chaplot, Andrea Piovano, Sebastien Diliberto, Stephanie Michel, Alain Maillard, Karol Strzalkowski, O. Pages
Inelastic neutron scattering measurements on the hexagonal Zn67Mg33S semiconductor alloy reveal a bimodal pattern of the optical modes across the Brillouin zone, confirmed by first-principles simulations. Such modes are sensitive to the local fluctuations in the composition inherent to random Zn/Mg alloying, distinguishing homo from hetero environments of a given bond (1-bond/2-mode), as is formalized for cubic alloys by the percolation model. The latter model thus emerges as a generic framework for systematizing the optical modes of semiconductor alloys in various crystal structures.
Materials Science (cond-mat.mtrl-sci)
30 pages, 14 figures
On the possibility of chiral symmetry breaking in liquid hydrogen peroxide
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
Roberto Menta, Pablo G. Debenedetti, Roberto Car, Pablo M. Piaggi
Molecular chirality is a key concept in chemistry with implications for the origin of life and the manufacturing of pharmaceuticals. Simulations of a chiral molecular model with an energetic bias towards homochiral interactions show spontaneous symmetry breaking wherein the liquid separates into two phases, each enriched in one of the two enantiomers. Here, we employ molecular dynamics simulations of a geometrically similar model with a semi-empirical force field and no explicit bias towards homochiral interactions, in order to test the possible existence of this phenomenon in hydrogen peroxide, the smallest chiral molecule. For this purpose, we study the fluid phase of this substance between 100 K and 1500 K, and from $10^{-4}$ GPa to 1 GPa. We find a glass transition and we suggest that hydrogen bonds, captured by our force field, play a central role in such behavior. We also test the possibility of observing chiral symmetry breaking by performing both constant temperature and cooling simulations at multiple pressures, and we do not observe the phenomenon. An analysis of the structure of the liquid shows negligible differences between homochiral and heterochiral interactions, supporting the difficulty in observing chiral fluid-phase separation. If hydrogen peroxide manifests spontaneous chiral symmetry breaking, it likely takes place significantly below room temperature and is hidden by other phenomena, such as the glass transition or crystallization. More broadly, our results, and recent experimental observations, suggest that greater molecular complexity is needed for spontaneous chiral symmetry breaking in the liquid phase to occur.
Statistical Mechanics (cond-mat.stat-mech), Soft Condensed Matter (cond-mat.soft)
LaTeX: 13 pages, 10 figures + Supp. Information
Engineering excitonic metal-insulator transitions in ultra-thin doped copper sulfides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Haiyang Chen, Yufeng Liu, Yashi Jiang, Changcang Qiao, Tao Zhang, Jianyang Ding, Zhengtai Liu, Zhenhua Chen, Yaobo Huang, Jinfeng Jia, Shiyong Wang, Peng Chen
Exciton condensation in the absence of optical excitation is proposed in 1960s to occur in a semiconductor at low temperatures when the binding energy of excitons overcomes the band gap or in a semimetal with weakly screened coulomb interaction, giving rise to an excitonic insulating state. However, it has been challenging to establish experimental realization in a natural material as the interacting electron-hole pockets rely on the band structures which are difficult to be delicately controlled. Here, we demonstrate an excitonic insulating phase formed in ultra-thin copper sulfide films by effectively tuning the band structure via changing the composition of Cu and S in the system. Using angle-resolved photoemission spectroscopy (ARPES), we observed a continuous band renormalization and opening of a full gap at low temperatures over a wide range of doping. The electronic origin of the metal-insulator transition is supported by scanning tunneling microscopy (STM) and low energy electron diffraction (LEED) measurements, which show no indication of superlattice modulation and lattice symmetry breaking. The evidence of excitonic insulator is further provided by carrier density dependent transitions, a combined effect of electron screening and Coulomb interaction strength. Our findings demonstrate the tunability of the band structure of copper sulfides, allowing for new opportunities to study exotic quantum phases.
Strongly Correlated Electrons (cond-mat.str-el)
Anti Kibble-Zurek behavior in the quantum XY spin-1/2 chain driven by correlated noisy magnetic field and anisotropy
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
S. Sadeghizade, R. Jafari, A. Langari
In the non-adiabatic dynamics across a quantum phase transition, the Kibble-Zurek paradigm describes that the average number of topological defects is suppressed as a universal power law with the quench time scale. A conflicting observation, which termed anti-Kibble-Zurek dynamics has been reported in several studies, specifically in the driven systems with an uncorrelated stochastic (white) noise. Here, we study the defect generation in the driven transverse field/anisotropy quantum $XY$ model in the presence of a correlated (colored) Gaussian noise. We propose a generic conjecture that properly capture the noise-induced excitation features, which shows good agreement with the numerical simulations. We show that, the dynamical features of defect density are modified by varying the noise correlation time. Our numerical simulations confirm that, for fast noises, the dynamics of the defect density is the same as that of the uncorrelated (white) noise, as is expected. However, the larger ratio of noise correlation time to the annealing time results in larger defects density formation and reforms the universal dynamical features. Our finding reveals that, the noise-induced defects scale linearly with the annealing time for fast noises, while in the presence of the slow noises, the noise-induced defects scale linearly with the square of the annealing time. The numerical simulations confirm that, the optimal annealing time, at which the defects density is minimum, scales linearly in logarithmic scale with the total noise power having different exponents for the fast and slow noises.
Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), Quantum Physics (quant-ph)
13 pages, 12 figures, to appear in PRB
Back-action effects in charge detection
New Submission | Mesoscale and Nanoscale Physics (cond-mat.mes-hall) | 2025-03-06 20:00 EST
Sarath Sankar, Matan Lotem, Joshua Folk, Eran Sela, Yigal Meir
Charge detection offers a powerful probe of mesoscopic structures based on quantum dots, but it also invariably results in measurement back-action (MBA). If strong, MBA can be detrimental to the physical properties being probed. In this work, we focus on the effects of MBA on an Anderson impurity model in which the impurity is coupled electrostatically to a detector. Introducing a novel non-perturbative method, we explore the interplay of coherent dynamics, strong correlations and non-equilibrium conditions. The effects of MBA can be seen most clearly in the temperature derivative of occupation. In the non-equilibrium case, we identify this as arising due to an energy flow from the detector to the impurity.
Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Strongly Correlated Electrons (cond-mat.str-el)
Spontaneous rotational symmetry breaking induced by electronic instability in the normal state of La_{1-x} Sr_{x} NiO_{2}
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Qiang Zhao, Rui Liu, Wen-Long Yang, Xue-Yan Wang, Jia-Kun Luo, Jing-Yuan Ma, Fang-Hui Zhu, Cheng-Xue Chen, Mei-Ling Yan, Rui-Fen Dou, Chang-Min Xiong, Chi Xu, Xing-Ye Lu, Hai-Wen Liu, Ji-Kun Chen, Zhi-Ping Yin, Jia-Cai Nie
The spontaneous rotational symmetry breaking (RSB), a hallmark phenomenon in cuprates and iron-based high-temperature superconductors, originates from intricate interactions between superconducting order and competing quantum states. Understanding this mechanism is pivotal for unraveling the microscopic origin of unconventional superconductivity. Although infinite-layer nickelates (ILNs) share similar crystalline structure and the same nominal 3d-electron configurations with cuprates, they have significant differences in Fermi surface topology, electronic band characteristics, and charge order. These distinctions make ILNs an ideal platform for studying RSB in unconventional superconductors. Through angular-resolved resistivity measurements within a large temperature and doping range, we identify pronounced RSB signatures near doping concentrations x=0.05 and 0.25. Based on the strongly correlated electronic structures from combined density functional theory and dynamical mean field theory calculations, we find that the calculated electronic susceptibility has a peak structure at the corresponding doping concentration, indicating pronounced electronic instabilities which drive RSB. Our findings reveal the important role of electronic correlation and Fermi surface nesting in the emergence of RSB. Our work not only deepens the understanding of electronic behavior in ILNs, but also provides new ideas and methods for exploring RSB in other unconventional superconductors.
Superconductivity (cond-mat.supr-con)
17pages,7figures
Exploring Dual-Iron Atomic Catalysts for Efficient Nitrogen Reduction: A Comprehensive Study on Structural and Electronic Optimization
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Zhe Zhang, Wenxin Ma, Jiajie Qiao, Xiaoliang Wu, Shaowen Yu, Weiye Hou, Xiang Huang, Rubin Huo, Hongbo Wu, Yusong Tu
The nitrogen reduction reaction (NRR), as an efficient and green pathway for ammonia synthesis, plays a crucial role in achieving on-demand ammonia production. This study proposes a novel design concept based on dual-iron atomic sites and nitrogen-boron co-doped graphene catalysts, exploring their high efficiency in NRR. By modulating the N and B co-doped ratios, we found that Fe2N3B@G catalyst exhibited significant activity in the adsorption and hydrogenation of N2 molecules, especially with the lowest free energy (0.32 eV) on NRR distal pathway, showing its excellent nitrogen activation capability and NRR performance. The computed electron localization function, crystal orbital Hamiltonian population, electrostatic potential map revealed that the improved NRR kinetics of Fe2N3B@G catalyst derived by N3B co-doping induced optimization of Fe-Fe electronic environment, regulation of Fe-N bond strength, and the continuous electronic support during the N2 breakage and hydrogenation. In particular, machine learning molecular dynamics (MLMD) simulations were employed to verify the high activity of Fe2N3B@G catalyst in NRR, which reveal that Fe2N3B@G effectively regulates the electron density of Fe-N bond, ensuring the smooth generation and desorption of NH3 molecules and avoiding the competition with hydrogen evolution reaction (HER). Furthermore, the determined higher HER overpotential of Fe2N3B@G catalyst can effectively inhibit the HER and enhance the selectivity toward NRR. In addition, Fe2N3B@G catalyst also showed good thermal stability by MD simulations up to 500 K, offering its feasibility in practical applications. This study demonstrates the superior performance of Fe2N3B@G in nitrogen reduction catalysis, and provides theoretical guidance for atomic catalyst design by the co-doping strategy and in-deep electronic environment modulation.
Materials Science (cond-mat.mtrl-sci), Chemical Physics (physics.chem-ph)
Unexpected Density Functional Dependence of the Antipolar $Pbcn$ Phase in HfO$_2$
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
The antipolar $Pbcn$ phase of HfO$_2$ has been suggested to play an important role in the phase transition and polarization switching mechanisms in ferroelectric hafnia. In this study, we perform a comprehensive benchmark of density functional theory (DFT) calculations and deep potential molecular dynamics (DPMD) simulations to investigate the thermodynamic stability and phase transition behavior of hafnia, with a particular focus on the relationship between the $Pbcn$ and ferroelectric $Pca2_1$ phases. Our results reveal significant discrepancies in the predicted stability of the $Pbcn$ phase relative to the $Pca2_1$ phase across different exchange-correlation functionals. Notably, the PBE and hybrid HSE06 functionals exhibit consistent trends, which diverge from the predictions of the PBEsol and SCAN functionals. For a given density functional, temperature-driven phase transitions predicted by DFT-based quasi-harmonic free energy calculations aligns with finite-temperature MD simulations using a deep potential trained on the same density functional. Specifically, the PBE functional predicts a transition from $Pca2_1$ to $Pbcn$ with increasing temperature, while PBEsol predicts a transition from $Pca2_1$ to $P4_2/nmc$. A particularly striking and reassuring finding is that under fixed mechanical boundary conditions defined by the ground-state structure of $Pca2_1$, all functionals predict consistent relative phase stabilities and comparable switching barriers as well as domain wall energies. These findings underscore the unique characteristics of the $Pbcn$ phase in influencing phase transitions and switching mechanisms in ferroelectric hafnia.
Materials Science (cond-mat.mtrl-sci), Computational Physics (physics.comp-ph)
Geometric Asymmetry-Enhanced Nonreciprocal Supercurrent Transport Revealed by Second-Harmonic Response
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Yu He, Zifeng Wang, Jiaxu Li, Fenglin Zhong, Haozhe Yang, Kewen Shi, Le Wang, Guang Yang, Weisheng Zhao
Nonreciprocal transport in superconducting systems serves as a powerful probe of symmetry-breaking mechanisms, with the superconducting diode effect emerging as a key manifestation enabling cryogenic rectification. While theoretical models have extensively explored superconducting nonreciprocity, experimental verification remains challenging, as conventional transport measurements struggle to disentangle intrinsic and extrinsic contributions. Nonlinear transport analysis, particularly second-harmonic response, offers an alternative approach by providing a sensitive probe for detecting spatial inversion symmetry breaking in the presence of time-reversal symmetry violation. Here, we systematically investigate the influence of geometric symmetry on nonreciprocal transport by comparing two triangular-extended Hall bar configurations with a symmetric Hall bar control. Second-harmonic nonlinear transport measurements reveal that the triangular extension significantly enhances nonreciprocal response, exhibiting a clear dependence on the base angle of the extension. These findings establish a direct connection between mesoscopic geometry and macroscopic nonreciprocity, demonstrating how spatial symmetry and vortex dynamics govern nonlinear transport. This insight offers a guiding principle for designing superconducting rectification architectures.
Superconductivity (cond-mat.supr-con)
17 pages, 4 figures
Kondo-like behavior in a mixed valent oxypnictide $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Szymon Królak (1), Michał J. Winiarski (1), Duygu Yazici (1 and 2), Soohyeon Shin (3), Tomasz Klimczuk (1) ((1) Faculty of Applied Physics and Mathematics and Advanced Materials Centre, Gdansk University of Technology, Gdańsk, Poland (2) The Scientific and Technological Research Council of Turkey, Ankara, Turkey (3) PSI Center for Neutron and Muon Sciences, Paul Scherrer Institut, Villigen, Switzerland)
We have synthesized and characterized the physical properties of a layered, mixed valent oxypnictide $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$ via magnetization, electrical resistivity, and specific heat measurements. Although $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$ does not exhibit superconductivity down to T = 0.5 K, it demonstrates an intriguing resistivity minimum observed at $\mathrm{T_{min}}$ = 13.7 K. Disappearance of the resistivity minimum under an applied magnetic field of $\mathrm{\mu_{0}H}$ = 9 T together with the negative magnetoresistance at low and positive at high temperatures are observed, which are typical for both Kondo-like spin-dependent scattering and 3D weak localization. We argue that the Kondo scattering is a more plausible explanation due to the low-temperature deviation from a Curie-Weiss law observed in the magnetic susceptibility, consistent with the presence of magnetic interactions between paramagnetic $\mathrm{Cu^{2+}}$ ions and Kondo screening of these $\mathrm{Cu^{2+}}$ moments. We supplemented the experimental characterization with a detailed description of chemical bonding, employing density functional theory (DFT) calculations and crystal orbital Hamilton population (COHP) analysis for $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$ and isostructural $\mathrm{La_{3}Ni_{4}P_{4}O_{2}}$, which is a superconductor with $\mathrm{T_c = 2.2}$ K. Based on the calculations performed, we present the difference between $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$ and $\mathrm{La_{3}Ni_{4}P_{4}O_{2}}$ in the character of electronic states at the Fermi level. This discrepancy impacts structural stability and may cause a lack of superconductivity in $\mathrm{La_{3}Cu_{4}P_{4}O_{2}}$ down to T = 0.5 K.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci), Superconductivity (cond-mat.supr-con)
13 pages, 9 figures
Sci Rep 15, 7019 (2025)
Photoluminescence Detection of Polytype Polarization in r-MoS2 Enabled by Asymmetric Dielectric Environments
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Idan Kizel, Omri Meron, Dror Hershkovitz, Maayan Vizner Stern, Alon Ron, Moshe Ben Shalom, Haim Suchowski
The rhombohedral (r) polytypes of transition metal dichalcogenides (TMDs) constitute a novel class of two-dimensional ferroelectric materials, where lateral shifts between parallel layers induce reversible out-of-plane polarization. This emerging field, known as SlideTronics, holds significant potential for next-generation electronic and optoelectronic applications. While extensive studies have investigated the effects of electrical and chemical doping on excitonic signatures in 2H-TMDs, as well as the influence of dielectric environments on their optical properties, the impact of intrinsic polarization in asymmetric environments remains largely unexplored. Here, we demonstrate a striking polarization-dependent photoluminescence (PL) contrast of up to 400% between ferroelectric domains in bilayer and trilayer rhombohedral molybdenum disulfide (r-MoS2). This pronounced contrast arises from an asymmetric dielectric environment, which induces polarization-dependent shifts in the Fermi energy, leading to a modulation of the exciton-trion population balance. A detailed temperature-dependent line shape analysis of the PL, conducted from 4K to room temperature, reveals domain-specific trends that further reinforce the connection between polarization states and excitonic properties. The persistence of these distinct optical signatures at room temperature establishes PL as a robust and non-invasive probe for ferroelectric domain characterization, particularly in fully encapsulated device architectures where conventional techniques, such as Kelvin probe force microscopy, become impractical.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Interaction-correlated random matrices
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
Abbas Ali Saberi, Sina Saber, Roderich Moessner
We introduce a family of random matrices where correlations between matrix elements are induced via interaction-derived Boltzmann factors. Varying these yields access to different ensembles. We find a universal scaling behavior of the finite-size statistics characterized by a heavy-tailed eigenvalue distribution whose extremes are governed by the Fréchet extreme value distribution for the case corresponding to a ferromagnetic Ising transition. The introduction of a finite density of nonlocal interactions restores standard random-matrix behavior. Suitably rescaled average extremes, playing a physical role as an order parameter, can thus discriminate aspects of the interaction structure; they also yield further nonuniversal information. In particular, the link between maximum eigenvalues and order parameters offers a potential route to resolving long-standing problems in statistical physics, such as deriving the exact magnetization scaling function in the two-dimensional Ising model at criticality.
Statistical Mechanics (cond-mat.stat-mech), Disordered Systems and Neural Networks (cond-mat.dis-nn), Mathematical Physics (math-ph)
4 figures
PRB(Letter) 110, L180102 (2024)
Revealing the electron-spin fluctuation coupling by photoemission in CaKFe4As4
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Peng Li, Yuzhe Wang, Yabin Liu, Jianghao Yao, Zhisheng Zhao, Zhengtai Liu, Dawei Shen, Huiqian Luo, Guanghan Cao, Juan Jiang, Donglai Feng
Electron-boson coupling in unconventional superconductors is one of the key parameters in understanding the superconducting pairing symmetry. Here, we report definitive photoemission evidence of electron-spin exciton coupling in the iron-based superconductor CaKFe4As4, obtained via high-resolution ARPES. Our study identifies a distinct kink structure on the {\alpha} band, observable only in the superconducting phase and closely linked with the superconductivity, indicative of strong electron-boson interactions. Notably, this kink structure corresponds to two distinct bosonic modes at 11 meV and 13 meV, aligning with spin resonance modes previously observed in inelastic neutron scattering experiments. This alignment underscores the significant role of antiferromagnetic fluctuations in the pairing mechanism of this superconductor. Furthermore, the unique momentum-dependent and orbital-selective properties of the coupling revealed by ARPES provide profound insights into the pairing symmetry, suggesting predominantly s_+- wave pairing facilitated by spin fluctuations. Our findings not only highlight the pivotal role of spin resonance in the superconductivity of CaKFe4As4 but also enhance understanding of the electron-spin exciton interactions in unconventional superconductors.
Superconductivity (cond-mat.supr-con)
Phys. Rev. X - Accepted 4 March, 2025
Dual spectroscopy of quantum simulated Fermi-Hubbard systems
New Submission | Quantum Gases (cond-mat.quant-gas) | 2025-03-06 20:00 EST
K. Knakkergaard Nielsen, M. Zwierlein, G. M. Bruun
Quantum gas microscopy with atoms in optical lattices provides remarkable insights into the real space properties of many-body systems, but does not directly reveal the nature of their fundamental excitation spectrum. Here, we demonstrate that radio-frequency spectroscopy can reveal the quasi-particle nature of doped quantum many-body systems, crucial for our understanding of, e.g., high-temperature superconductors. In particular, we showcase how the existence and energy of magnetic polaron quasi-particles in doped Fermi-Hubbard systems may be probed, revealed by hallmark peaks in the spectroscopic spectrum. In combination with fundamental dualities of the Fermi-Hubbard model, we describe how these findings may be tested using several experimental platforms.
Quantum Gases (cond-mat.quant-gas), Strongly Correlated Electrons (cond-mat.str-el), Superconductivity (cond-mat.supr-con)
9 pages, 3 figures
Atomistically informed phase field study of austenite grain growth
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Ayush Suhane, Daniel Scheiber, Vsevolod I. Razumovskiy, Matthias Militzer
Atomistically-informed phase field simulations have been performed to investigate the effect of five common alloying elements (Nb, Ti, Mo, V, Mn) on austenite grain growth. The anisotropic simulations based on the segregation energy profiles of the solutes to four different grain boundary (GB) types from density functional theory calculations suggest a secondary role of solute drag anisotropy on grain growth. Hence, the solute trends are determined to be the same for all investigated GBs, and as a result, the $\Sigma 5(310)[001]$ GB can be considered as a representative GB for solute trend predictions. The decrease in grain growth rates due to solute additions is quantitatively described using a solute trend parameter. The following hierarchy of the solute’s effectiveness to retard austenite grain growth has been determined based on the results of the presented model calculations in agreement with the experimental observations: Nb$>$Ti$>$Mo$>$V$\approx$Mn. The limitations and the strengths of the proposed approach are discussed in detail, and a potential application of this approach to steel design is proposed.
Materials Science (cond-mat.mtrl-sci)
Computational Materials Science, Volume 228, September 2023, 112300
Modeling solute-grain boundary interactions in a bcc Ti-Mo alloy using density functional theory
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Hariharan Umashankar, Daniel Scheiber, Vsevolod I. Razumovskiy, Matthias Militzer
Solute segregation in alloys is a key phenomenon which affects various material characteristics such as embrittlement, grain growth and precipitation kinetics. In this work, the segregation energies of Y, Zr, and Nb to a \textgreek{S}5 grain boundary in a bcc Ti-25 at % Mo alloy were determined using density functional theory (DFT) calculations. A systematic approach was laid out by computing the solution energy distributions in the bulk alloy using Warren-Cowley short-range order parameters to find a representative bulk-solute reference energy. Additionally, different scenarios were considered when a solute atom replaces different sites in terms of their local Ti-Mo chemistry at the GB plane to calculate the distribution of segregation energies. The solute segregation to a Mo site at the GB plane is preferred rather than to a Ti site. Further analysis shows that these segregation energy trends can be rationalized based on a primarily elastic interaction. Thus the segregation energies scale with the solute size such that Y has the largest segregation energies followed by Zr and Nb.
Materials Science (cond-mat.mtrl-sci)
Computational Materials Science, Volume 229, 5 October 2023, 112393
Quantum Batteries: A Materials Science Perspective
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
A. Camposeo (1), T. Virgili (2), F. Lombardi (3), G. Cerullo (2,4), D. Pisignano (1,5), M. Polini (5) ((1) NEST, Istituto Nanoscienze-CNR, (2) Istituto di Fotonica e Nanotecnologie - CNR, IFN, (3) Department of Microtechnology and Nanoscience, Chalmers University of Technology, (4) Dipartimento di Fisica, Politecnico di Milano, (5) Dipartimento di Fisica, Università di Pisa)
In the context of quantum thermodynamics, quantum batteries have emerged as promising devices for energy storage and manipulation. Over the past decade, substantial progress has been made in understanding the fundamental properties of quantum batteries, with several experimental implementations showing great promise. This Perspective provides an overview of the solid-state materials platforms that could lead to fully operational quantum batteries. After briefly introducing the basic features of quantum batteries, we discuss organic microcavities, where superextensive charging has already been demonstrated experimentally. We then explore other materials, including inorganic nanostructures (such as quantum wells and dots), perovskite systems, and (normal and high-temperature) superconductors. Key achievements in these areas, relevant to the experimental realization of quantum batteries, are highlighted. We also address challenges and future research directions. Despite their enormous potential for energy storage devices, research into advanced materials for quantum batteries is still in its infancy. This paper aims to stimulate interdisciplinarity and convergence among different materials science research communities to accelerate the development of new materials and device architectures for quantum batteries.
Materials Science (cond-mat.mtrl-sci), Applied Physics (physics.app-ph)
54 pages, 8 Figures, Advanced Materials 2025
IsoME: Streamlining High-Precision Eliashberg Calculations
New Submission | Superconductivity (cond-mat.supr-con) | 2025-03-06 20:00 EST
Eva Kogler, Dominik Spath, Roman Lucrezi, Hitoshi Mori, Zien Zhu, Zhenglu Li, Elena R. Margine, Christoph Heil
This paper introduces the Julia package IsoME, an easy-to-use yet accurate and robust computational tool designed to calculate superconducting properties. Multiple levels of approximation are supported, ranging from the basic McMillan-Allen-Dynes formula and its machine learning-enhanced variant to Eliashberg theory including static Coulomb interactions derived from $GW$ calculations, offering a fully ab initio approach to determine superconducting properties, such as the critical superconducting temperature ($T_\text{c}$) and the superconducting gap function ($\Delta$). We validate IsoME by benchmarking it against various materials, demonstrating its versatility and performance across different theoretical levels. The findings indicate that the previously held assumption that Eliashberg theory overestimates $T_\text{c}$ is no longer valid when $\mu^\ast$ is appropriately adjusted to account for the finite Matsubara frequency cutoff. Furthermore, we conclude that the constant density of states (DOS) approximation remains accurate in most cases. By unifying multiple approximation schemes within a single framework, IsoME combines first-principles precision with computational efficiency, enabling seamless integration into high-throughput workflows through its $T_\text{c}$ search mode. This makes IsoME a powerful and reliable tool for advancing superconductivity research.
Superconductivity (cond-mat.supr-con), Materials Science (cond-mat.mtrl-sci)
Beginner’s Lecture Notes on Quantum Spin Chains, Exact Diagonalization and Tensor Networks
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Guglielmo Lami, Mario Collura, Nishan Ranabhat
Aimed at introducing readers to the physics of strongly correlated many-body systems, these notes focus on numerical methods, with detailed discussions on implementing working code for exact diagonalization. A brief introduction to tensor network methods is also included. Prepared for the Summer School Quantumandu, held at Tribhuvan University (Kathmandu, Nepal) from 25 to 31 July 2024, as part of the ICTP’s Physics Without Frontiers program, these notes are primarily intended for readers encountering this field for the first time.
Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Structure and dynamics of a Rouse polymer in a fluctuating correlated medium
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Pietro Luigi Muzzeddu, Davide Venturelli, Andrea Gambassi
We study the static and dynamical properties of a harmonically confined Rouse polymer coupled to a fluctuating correlated medium, which affect each other reciprocally during their stochastic evolution. The medium is modeled by a scalar Gaussian field $\phi(\mathbf{x},t)$, which can feature modes with slow relaxation and long-range spatial correlations. We show that these modes affect the long-time behavior of the center-of-mass position of the polymer, which, after a displacement, turns out to relax algebraically towards its equilibrium position. In contrast, we show that the coupling to the medium speeds up the relaxation of higher Rouse modes. We further characterize the typical size of the polymer as a function of its polymerization degree and of the correlation length of the medium, in particular when the system is driven out of equilibrium via the application of a constant external driving force. Finally, we study the response of a linear polymer to a tensile force acting on its terminal monomers.
Soft Condensed Matter (cond-mat.soft), Statistical Mechanics (cond-mat.stat-mech)
14+5 pages, 7+1 figures
Orbital textures and evolution of correlated insulating state in monolayer 1T phase transition metal dichalcogenides
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Qiang Gao, Haiyang Chen, Wen-shin Lu, Yang-hao Chan, Zhenhua Chen, Yaobo Huang, Zhengtai Liu, Peng Chen
Strong electron-electron interaction can induce Mott insulating state, which is believed to host unusual correlated phenomena such as quantum spin liquid when quantum fluctuation dominates and unconventional superconductivity through doping. Transition metal compounds as correlated materials provide a versatile platform to engineer the Mott insulating state. Previous studies mostly focused on the controlling of the repulsive interaction and bandwidth of the electrons by gating or doping. Here, we performed angle-resolved photoemission spectroscopy (ARPES) on monolayer 1T phase NbSe2, TaSe2, and TaS2 and directly observed their band structures with characteristic lower Hubbard bands. By systematically investigating the orbital textures and temperature dependence of the energy gap of the materials in this family, we discovered that hybridization of the chalcogen p states with lower Hubbard band stabilizes the Mott phase via tuning of the bandwidth, as shown by a significant increase of the transition temperature (TC) at a stronger hybridization strength. Our findings reveal a mechanism for realizing a robust Mott insulating phase and establish monolayer 1T phase transition metal dichalcogenide family as a promising platform for exploring correlated electron problems.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Theory of Cation Solvation in the Helmholtz Layer of Li-ion Battery Electrolytes
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
Zachary A. H. Goodwin, Daniel M. Markiewitz, Qisheng Wu, Yue Qi, Martin Z. Bazant
The solvation environments of Li$^+$ in conventional non-aqueous battery electrolytes, such as LiPF$_6$ in mixtures of ethylene carbaronate (EC) and ethyl methyl carbonate (EMC), are often used to rationalize the transport properties of electrolytes and solid electrolyte interphase (SEI) formation. In the SEI, the solvation environments in the compact electrical double layer (EDL) next to the electrode, also known as the Helmholtz layer, determine (partially) what species can react to form the SEI, with bulk solvation environments often being used as a proxy. Here we develop and test a theory of cation solvation in the Helmholtz layer of non-aqueous Li-ion battery electrolytes. First, we validate the theory against bulk and diffuse EDL atomistic molecular dynamics (MD) simulations of LiPF$_6$ EC/EMC mixtures as a function of surface charge, where we find the theory can capture the solvation environments well. Next we turn to the Helmholtz layer, where we find that the main effect of the solvation structures next to the electrode is an apparent reduction in the number of binding sites between Li$^+$ and the solvents, again where we find good agreement with our developed theory. Finally, by solving a simplified version of the theory, we find that the probability of Li$^+$ binding to each solvent remains equal to the bulk probability, suggesting that the bulk solvation environments are a reasonable place to start when understanding new battery electrolytes. Our developed formalism can be parameterized from bulk MD simulations and used to predict the solvation environments in the Helmholtz layer, which can be used to determine what could react and form the SEI.
Statistical Mechanics (cond-mat.stat-mech), Materials Science (cond-mat.mtrl-sci)
Stability, growth, and doping of In${2}$(Si, Ge)${2}$O$_{7}$ as promising n-type wide-gap semiconductors
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Cheng-Wei Lee, Kingsley Egbo, Emily Garrity, Matthew Jankousky, Henry Garland, Andriy Zakutayev, Vladan Stevanović
In this paper we investigate, computationally and experimentally, the phase stability, electronic structure properties, and the propensity for n-type doping of In${2}$X${2}$O${7}$ (X=Si, Ge) ternary oxides. This family of materials contains promising novel wide-gap semiconductors based on their estimated high $n$-type Baliga figures of merit and acceptable thermal conductivity for power electronics applications. Here, we find that both In${2}$Si${2}$O${7}$ and In${2}$Ge${2}$O${7}$ to be n-type dopable, with Zr providing between 10$^{16}$ and above 10$^{21}$ cm$^{-3}$ net donor concentrations under O-poor conditions, depending on the chemistry, structure (ground-state thorvetite or high-pressure pyrochlore) and synthesis temperature. Initial thin-film growth and annealing leads to polycrystalline In${2}$Ge${2}$O${7}$ thin films in thorvetite structure with band gap over 4 eV, and confirms Zr doping predictions by achieving electron concentrations at 10$^{14}$-10$^{16}$ cm$^{-3}$ under O-rich condition. While future epitaxial growth development is still needed, this study establishes In${2}$X${2}$O$_{7}$ as promising n-type wide-gap semiconductors for power electronic applications.
Materials Science (cond-mat.mtrl-sci)
Effect of Ag nano-additivation on microstructure formation in Nd-Fe-B magnets built by laser powder bed fusion
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Varatharaja Nallathambi, Philipp Gabriel, Xinren Chen, Ziyuan Rao, Konstantin Skokov, Oliver Gutfleisch, Stephan Barcikowski, Anna Rosa Ziefuss, Baptiste Gault
Laser powder bed fusion (PBF-LB/M) enables the near-net shape production of permanent magnets with complex geometry while reducing material waste. However, controlling the microstructure and optimizing magnetic properties remain challenging due to rapid solidification and intrinsic heat treatment effects occurring during both inter-layer and intra-layer processing. Surface additivation of the feedstock powder with Ag nanoparticles (NPs) is a concept that has been shown to increase the coercivity of PBF-LB/M-produced Nd-Fe-B magnets. Using atom probe tomography (APT) and transmission electron microscopy (TEM), we reveal that Ag nano-additivation promotes heterogeneous nucleation of the Nd2Fe14B phase, leading to refined, equiaxed grains and increased stability of the Ti-Zr-B-rich intergranular phase. The intrinsic heat treatment, influenced by layer-wise processing, further affects the distribution of Ag-rich regions, impacting grain growth and intergranular phase composition across different regions of the melt pool. Compared to the unadditivated sample, the Ag-additivated sample exhibits a significantly finer grain structure and a changed intergranular phase, which contribute to enhanced domain wall pinning and coercivity. These microstructural changes directly modify the magnetic domain structure, as evidenced by Lorentz transmission electron microscopy (TEM). Our results highlight that the interplay between nano-additivation and in-process heat treatment provides a novel pathway for tailoring the microstructure and enhancing the magnetic performance of permanent magnets.
Materials Science (cond-mat.mtrl-sci)
Spin Models and Cluster Multipole Method: Application to Kagome Magnets
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Juba Bouaziz, Takuya Nomoto, Ryotaro Arita
We present a multi-scale computational approach that combines atomistic spin models with the cluster multipole (CMP) method. The CMP method enables a systematic and accurate generation of complex non-collinear magnetic structures using symmetry-adapted representations. The parameters of the spin model are derived from density functional theory using the magnetic force theorem, with the paramagnetic state as a reference. The energy landscape of CMP-generated structures is inspected at the model Hamiltonian level, and sets of low-energy magnetic structures are identified for each material candidate. The inclusion of relativistic antisymmetric and anisotropic pair interactions lifts partially the degeneracy among these most stable structures. To demonstrate the applicability and predictive capability of the method, we apply it to the non-collinear Mn3X and collinear Fe3X (X = Ga, Ge, and Sn) kagome compounds. The computational efficiency of the method in identifying low-energy structures among multiple CMP configurations highlights its potential for high-throughput screening of complex magnets with unknown magnetic order.
Materials Science (cond-mat.mtrl-sci), Strongly Correlated Electrons (cond-mat.str-el)
18 pages
Bacterial Turbulence in Shear Thinning Fluid
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Hongyi Bian, Chunhe Li, Jin Zhu, Zijie Qu
The collective motion of bacteria, commonly referred to as bacterial turbulence, is well understood in Newtonian fluids. However, studies on complex fluids have predominantly focused on viscoelastic effects. In our experiments, we employed Ficoll and Methocel polymers to compare the impacts of Newtonian and shear-thinning fluids on bacterial turbulence. We reported various physical properties, including energy and enstrophy, and observed that the shear-thinning effect is significantly suppressed in high-concentration bacterial suspensions. This suppression is largely attributed to the disruption of chain-like polymer structures around bacterial flagella due to strong interbacterial interactions in dense suspensions. To validate this hypothesis, we conducted experiments across bacterial concentrations (within the range where bacterial turbulence forms) and verified the findings using theoretical calculations based on the modified Resistive Force Theory (RFT).
Soft Condensed Matter (cond-mat.soft), Biological Physics (physics.bio-ph)
Atomistic modeling of functionalized magnetite surfaces with oxidation states
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
Emre Gürsoy, Gregor B. Vonbun-Feldbauer, Robert H. Meißner
Understanding the atomic structure of magnetite-carboxylic acid interfaces is crucial for tailoring nanocomposites involving this interface. We present a Monte Carlo (MC)-based method utilizing iron oxidation state exchange to model magnetite interfaces with tens of thousands of atoms - scales typically inaccessible by electronic structure calculations. By comparing the binding site preferences of carboxylic acids obtained from electronic structure calculations, we validated the accuracy of our method. We found that the oxidation state distribution, and thus the binding site preference depends on the surface thickness and coverage. We found that the oxidation state distribution, and consequently binding site preference, depend on coverage and surface thickness, with a critical thickness signaling the transition from layered to bulk-like oxidation states. The method presented here needs no interface specific parameterization, ensuring seamless compatibility with popular bimolecular force fields providing transferability, and simplifying the study of magnetite interfaces in general.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
Lithographically-controlled liquid metal diffusion in graphene: Fabrication and magneto-transport signatures of superconductivity
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
S. Wundrack, M. Bothe, M. Jaime, K. Kuester, M. Gruschwitz, Z. Mamiyev, P. Schaedlich, B. Matta, S. Datta, M. Eckert, C. Tegenkamp, U. Starke, R. Stosch, H.W. Schumacher, T. Seyller, K. Pierz, T. Tschirner, A. Bakin
Metal intercalation in epitaxial graphene enables the emergence of proximity-induced superconductivity and modified quantum transport properties. However, systematic transport studies of intercalated graphene have been hindered by challenges in device fabrication, including processing-induced deintercalation and instability under standard lithographic techniques. Here, we introduce a lithographically controlled intercalation approach that enables the scalable fabrication of gallium-intercalated quasi-freestanding bilayer graphene (QFBLG) Hall bar devices. By integrating lithographic structuring with subsequent intercalation through dedicated intercalation channels, this method ensures precise control over metal incorporation while preserving device integrity. Magneto-transport measurements reveal superconductivity with a critical temperature Tc,onset ~ 3.5 K and the occurrence of a transverse resistance, including both symmetric and antisymmetric field components, which is attributed to the symmetric-in-field component to non-uniform currents. These results establish an advanced fabrication method for intercalated graphene devices, providing access to systematic investigations of confined 2D superconductivity and emergent electronic phases in van der Waals heterostructures.
Materials Science (cond-mat.mtrl-sci), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
22 pages, 6 figures
The Roles of Size, Packing, and Cohesion in the Emergence of Force Chains in Granular Packings
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Ankit Shrivastava, Kaushik Dayal, Hae Young Noh
This study investigates computationally the impact of particle size disparity and cohesion on force chain formation in granular media. The granular media considered in this study are bi-disperse systems under uniaxial compression, consisting of spherical, frictionless particles that interact through a modified Hookean model. Force chains in granular media are characterized as networks of particles that meet specific criteria for particle stress and inter-particle forces. The computational setup decouples the effects of particle packing on force chain formations, ensuring an independent assessment of particle size distribution and cohesion on force chain formation. The decoupling is achieved by characterizing particle packing through the radial density function, which enables the identification of systems with both regular and irregular packing. The fraction of particles in the force chains network is used to quantify the presence of the force chains.
The findings show that particle size disparity promotes force chain formation in granular media with nearly-regular packing (i.e., an almost-ordered system). However, as particle size disparities grow, it promotes irregular packing (i.e., a disordered systems), leading to fewer force chains carrying larger loads than in ordered systems. Further, it is observed that the increased cohesion in granular systems leads to fewer force chains irrespective of particle size or packing.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Intermediate band analysis in Green’s functions calculations of quasiparticle interference
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Xinze Yang, Alexander F. Kemper, Adrian Gozar, Eduardo H. da Silva Neto
The measurement of quasiparticle scattering patterns on material surfaces using scanning tunneling microscopy (STM) is now an established technique for accessing the momentum-resolved electronic band structure of solids. However, since these quasiparticle interference (QPI) patterns reflect spatial variations related to differences in the band momenta rather than the momenta themselves, their interpretation often relies on comparisons with simple geometrical models such as the joint density of states (JDOS) or with the convolution of Green’s functions. In this paper, we highlight non-intuitive differences between Green’s function and JDOS results. To understand the origin of these discrepancies, we analyze the convolution of Green’s functions using the Feynman parametrization technique and introduce a framework that we call the intermediate band analysis. This approach allows us to derive simple selection rules for interband QPI, based on electron group velocities. Connecting the intermediate band analysis with the experiment, we consider experimental Bogoliubov QPI patterns measured for FeSe1-xSx, which were recently used to demonstrate a highly anisotropic superconducting gap, indicating superconductivity mediated by nematic fluctuations [1]. The calculated Green’s functions convolutions reproduce the particle-hole asymmetry in the intensity of QPI patterns across the Fermi level observed in experiments. Finally, we demonstrate the utility of intermediate band analysis in tracing the origin of this asymmetry to a coherence factor effect of the superconducting state.
Strongly Correlated Electrons (cond-mat.str-el)
The cost of resetting discrete-time random walks
New Submission | Statistical Mechanics (cond-mat.stat-mech) | 2025-03-06 20:00 EST
John C. Sunil, Richard A. Blythe, Martin R. Evans, Satya N. Majumdar
We consider a discrete-time continuous-space random walk, with a symmetric jump distribution, under stochastic resetting. Associated with the random walker are cost functions for jumps and resets, and we calculate the distribution of the total cost for the random walker up to the first passage to the target. By using the backward master equation approach we demonstrate that the distribution of the total cost up to the first passage to the target can be reduced to a Wiener-Hopf integral equation. The resulting integral equation can be exactly solved (in Laplace space) for arbitrary cost functions for the jump and selected functions for the reset cost. We show that the large cost behaviour is dominated by resetting or the jump distribution according to the choice of the jump distribution. In the important case of a Laplace jump distribution, which corresponds to run-and-tumble particle dynamics, and linear costs for jumps and resetting, the Wiener-Hopf equation simplifies to a differential equation which can easily be solved.
Statistical Mechanics (cond-mat.stat-mech)
26 pages, 6 figures
Quantum geometry and local moment swapover in correlated graphene heterostructures
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Niklas Witt, Siheon Ryee, Lennart Klebl, Jennifer Cano, Giorgio Sangiovanni, Tim O. Wehling
Graphene-based multilayer systems serve as versatile platforms for exploring the interplay between electron correlation and topology, thanks to distinctive low-energy bands marked by significant quantum metric and Berry curvature from graphene’s Dirac bands. Here, we investigate Mott physics and local spin moments in Dirac bands hybridized with a flat band of localized orbitals in functionalized graphene. Via hybridization control, a topological transition is realized between two symmetry-distinct site-selective Mott states featuring local moments in different Wyckoff positions, with a geometrically enforced metallic state emerging in between. We find that this geometrically controlled local moment ``swapover’’ and associated metal-insulator physics may be realized through proximity coupling of epitaxial graphene on SiC(0001) with group IV intercalants, where the Mott state faces geometrical obstruction in the large-hybridization limit. Our work shows that chemically functionalized graphene provides a correlated electron platform, very similar to the topological heavy fermions in graphene moiré systems but at significantly enhanced characteristic energy scales.
Strongly Correlated Electrons (cond-mat.str-el), Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
9 pages, 4 figures
Ultra-stretchable and Self-Healable Vitrimers with Tuneable Damping and Mechanical Response
New Submission | Soft Condensed Matter (cond-mat.soft) | 2025-03-06 20:00 EST
Jiaxin Zhao, Nicholas J. Warren, Richard Mandle, Peter Hine, Daniel J Read, Andrew J. Wilson, Johan Mattsson
Vitrimers are a relatively new class of polymer materials with unique properties offered by cross-links that can undergo associative exchange dynamics. We here present a new class of vitrimers based on poly(methyl acrylate) with cross-links utilising dioxaboralane metathesis. These vitrimers demonstrate a combination of ultra-stretchability (up to $\sim$ 80 times their own length), mechanical toughness ($\sim$ 40 MJ/m$^3$), and thermal stability up to $T\sim$ 250 °C; moreover, the vitrimers demonstrate excellent mechanical damping characterised by a loss factor ($\tan(\delta)$) with a maximum of $\sim$ 2-3 and an effective value $>$0.3 across five decades in frequency (0.001-100 Hz), or correspondingly across a $T$-range of $\sim$ 35 °C near room temperature (for a probe frequency of 1 Hz). The vitrimers can be successfully re-processed using both a thermo-mechanical and a chemical processing route, and can self-heal at room temperature, making them suitable for sustainable applications. The material properties are directly tuneable by variation of both the amount of cross-linker and by the degree of curing. Thus, this class of vitrimers are promising for applications where stretchability combined with mechanical toughness and/or a high mechanical dissipation is required.
Soft Condensed Matter (cond-mat.soft), Materials Science (cond-mat.mtrl-sci)
Main manuscript: 16 pages, 6 figures; Supplementary Information: 10 pages, 15 figures, 3 tables
Many-Body Localization and Particle Statistics in Disordered Bose-Hubbard Model
New Submission | Disordered Systems and Neural Networks (cond-mat.dis-nn) | 2025-03-06 20:00 EST
Jie Chen, Chun Chen, Xiaoqun Wang
We study the potential influence of the particle statistics on the stability of the many-body localization in the disordered Bose-Hubbard model. Within the higher-energy section of the dynamical phase diagram, we find that there is no apparent finite-size boundary drift between the thermal phase and the many-body localized regime. We substantiate this observation by introducing the Van Vleck perturbation theory into the field of many-body localization. The appropriateness of this method rests largely on the peculiar Hilbert-space structure enabled by the particles’ Bose statistics. The situation is reversed in the lower-energy section of the dynamical phase diagram, where the significant finite-size boundary drift pushes the putative many-body localized regime up to the greater disorder strengths. We utilize the algebraic projection method to make a connection linking the disordered Bose-Hubbard model in the lower-energy section to an intricate disordered spin chain model. This issue of the finite-size drift could hence be analogous to what happens in the disordered Heisenberg chain. Both trends might be traced back to the particles’ intrinsic or emergent Fermi statistics.
Disordered Systems and Neural Networks (cond-mat.dis-nn), Strongly Correlated Electrons (cond-mat.str-el), Quantum Physics (quant-ph)
Discovery of intertwined spin and charge density waves in a layered altermagnet
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Christopher Candelora, Muxian Xu, Siyu Cheng, Alessandro De Vita, Davide Romanin, Chiara Bigi, My Bang Petersen, Alexander LaFleur, Matteo Calandra, Jill Miwa, Younghun Hwang, Ziqiang Wang, Federico Mazzola, Ilija Zeljkovic
Altermagnets recently came into the spotlight as a new class of magnetic materials, arising as a consequence of specific crystal symmetries. They are characterized by a spin-polarized electronic band structure similar to ferromagnets, but with net zero magnetization, and touted as a promising platform to host a slew of exotic properties, many of which are yet to be explored. Using spectroscopic-imaging scanning tunneling microscopy (STM) and spin-polarized STM, we discover intertwined spin and charge density waves in a layered triangular lattice altermagnet, Co-intercalated NbSe$_2$. STM topographs and differential conductance maps in the altermagnetic state show tri-directional modulations with a 2$a_0$ wave length that are robustly present and non-dispersive in a wide range of imaging biases, suggesting a charge ordering origin of the modulations. Spin-polarized STM measurements further reveal that the amplitude of the charge modulations is sensitive to the spin polarization of the tip. This observation demonstrates an additional spin modulation associated with the density wave modulations. Our work uncovers the first density wave instability involving both charge and spin degrees of freedom in an altermagnetic system, accomplished by providing elusive atomic-scale insights. Our experiments thus set the foundation for the studies of correlated electronic states in altermagnets, and motivate comprehensive explorations of intercalated quasi-2D transition metal dichalcogenides in the search for novel phenomena in altermagnets.
Strongly Correlated Electrons (cond-mat.str-el), Materials Science (cond-mat.mtrl-sci)
Evaluating Compression and Nanoindentation in FCC Nickel: A Methodology for Interatomic Potential Selection
New Submission | Materials Science (cond-mat.mtrl-sci) | 2025-03-06 20:00 EST
K. Cichocki, F. J. Dominguez-Gutierrez, L. Kurpaska, K. Muszka
We performed molecular dynamics simulations to investigate the mechanical response of face-centered cubic (FCC) nickel under uniaxial compression and nanoindentation using traditional interatomic potentials, including the Embedded Atom Method (EAM) and Modified Embedded Atom Method (MEAM). By calculating the generalized stacking fault energy (GSFE), we analyzed the dissociated slip paths responsible for stacking fault formation and partial Shockley dislocations during mechanical loading. Our findings highlight the critical importance of selecting appropriate interatomic potentials to model compression and nanoindentation tests accurately, aligning simulations with experimental observations. We propose a practical methodology for identifying empirical interatomic potentials suitable for mechanical testing of single-element materials. This approach establishes a benchmark for FCC nickel simulations and provides a basis for extending these methods to more complex Ni-based alloys, facilitating comparisons with experimental results such as those from electron microscopy.
Materials Science (cond-mat.mtrl-sci)
Quantum effects on pyrochlore higher-rank U(1) spin liquids: pinch-line singularities, spin nematics, and connections to oxide materials
New Submission | Strongly Correlated Electrons (cond-mat.str-el) | 2025-03-06 20:00 EST
Lasse Gresista, Daniel Lozano-Gómez, Matthias Vojta, Simon Trebst, Yasir Iqbal
Motivated by the magnetism of pyrochlore oxides, we consider the effect of quantum fluctuations in the most general symmetry-allowed nearest-neighbor Kramers exchange Hamiltonian on the pyrochlore lattice. At the classical level, this Hamiltonian exhibits a rich landscape of classical spin liquids and a variety of non-conventional magnetic phases. In contrast, much remains unclear for the quantum model, where quantum fluctuations have the potential to alter the classical landscape and stabilize novel magnetic phases. Employing state-of-the-art pseudo-fermion functional renormalization group (pf-FRG) calculations for the spin-$1/2$ model, we determine the quantum phase diagram at relevant cross-sections, where the classical model hosts an algebraic nodal rank-2 spin liquid and a spin nematic order. We find large regions in parameter space where dipolar magnetic order is absent and, based on known fingerprints in the correlation functions, suggest that this non-conventional region is composed of an ensemble of distinct phases stabilized by quantum fluctuations. Our results hint at the existence of a spin nematic phase, and we identify the quantum analogue of the classical rank-2 spin liquid. Furthermore, we highlight the importance of assessing the subtle interplay of quantum and thermal fluctuations in reconciling the experimental findings on the nature of magnetic order in Yb$_2$Ti$_2$O$_7$.
Strongly Correlated Electrons (cond-mat.str-el)
21 pages, 13 figures