Journal of Physics: Condensed Matter最新文献

{"title":"Comparing dynamics, pinning and ratchet effects for skyrmionium, skyrmions, and antiskyrmions.","authors":"J C Bellizotti Souza, N P Vizarim, C J O Reichhardt, C Reichhardt, P A Venegas","doi":"10.1088/1361-648X/adbba6","DOIUrl":"10.1088/1361-648X/adbba6","url":null,"abstract":"<p><p>We compare the driven dynamics of skyrmions, antiskyrmions, and skyrmionium interacting with random disorder, circular defects, and asymmetric potentials. When interacting with a line defect at a constant drive, skyrmions and antiskyrmions show an acceleration effect for motion along the wall and a drop in velocity when they can cross the barrier. In contrast, skyrmionium travels at a reduced velocity when moving along a wall, and exhibits an increase in velocity once it can cross the barrier. For point defects, skyrmionium can be pinned for a finite fixed period of time, while for skyrmions and antiskyrmions, the Magnus force creates a deflection from the defect and an acceleration effect. For a given drive, skyrmionium moves twice as fast as skyrmions; however, skyrmionium is more susceptible to pinning effects than skyrmions and antiskyrmions. Additionally, there is a critical threshold where the skyrmionium transforms to a skyrmion that is associated with a drop in the velocity of the texture. We show that all three textures exhibit diode and ratchet effects when interacting with an asymmetric substrate, but skyrmions and antiskyrmions show a stronger ratcheting effect than skyrmionium due to the Magnus force.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143531547","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fundamental aspects of Aharonov-Bohm quantum machines: thermoelectric heat engines and diodes.","authors":"Salil Bedkihal, Jayasmita Behera, Malay Bandyopadhyay","doi":"10.1088/1361-648X/adb921","DOIUrl":"10.1088/1361-648X/adb921","url":null,"abstract":"<p><p>The study of heat-to-work conversion has garnered significant attention in recent years, underscoring the potential of nanoscale systems to achieve energy conversion in steady-state devices without the involvement of macroscopic moving parts. The operation of these devices relies on the steady-state flows of quantum particles, including electrons, photons, and phonons. This review explores the theoretical frameworks that govern these steady-state flows within various mesoscopic or nanoscale devices, such as thermoelectric heat engines, with a particular focus on quantum dot (QD) Aharonov-Bohm (AB) interferometric configurations. Quantum interference effects, in particular, show great promise for enhancing the thermoelectric transport properties of these quantum devices. By enabling precise control over energy levels and transport pathways, such effects can significantly improve heat-to-work conversion efficiency. Driven QD AB networks provide an ideal platform for studying these engines due to their ability to maintain quantum coherence and offer precise experimental control. Unlike bulk systems, nanoscale systems such as QDs exhibit unique quantum interference phenomena, including sharp features in transmission spectra and Fano resonances. This review highlights the distinction between optimization methods that produce boxcar functions and coherent control methods that yield complex interference patterns. It demonstrates that the effective design of thermoelectric heat engines requires the careful tailoring of quantum interference and magnetic field-induced effects to enhance performance. Additionally, it addresses fundamental questions regarding the bounds of these thermoelectric machines, with particular emphasis on how magnetic fields can alter the limits of power or efficiency and the interplay between quantum transport theories and the laws of thermodynamics. Thermoelectric devices with broken time-reversal symmetry provide valuable insights into directional dependencies and asymmetries in quantum transport. This review offers a comprehensive overview of past and present research on quantum thermoelectric heat engines utilizing the AB effect. Special attention is given to three-terminal AB heat engines, where broken time-reversal symmetry can induce a coherent diode effect. Furthermore, the review examines bounds on power and efficiency in systems with broken time-reversal symmetry. We conclude by presenting open questions, summarizing key findings, and offering insights into future directions in the field of quantum thermoelectric heat engines.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large bulk photovoltaic effect and Fermi-surface-mediated enhancement with chemical potential in ZnGeP₂.","authors":"Banasree Sadhukhan","doi":"10.1088/1361-648X/adbb48","DOIUrl":"10.1088/1361-648X/adbb48","url":null,"abstract":"<p><p>Bulk photovoltaic effect is a non-linear response in noncentrosymmetric materials that converts light into DC current. In this work, we investigate the optical linear and non-linear responses in a chalcopyrite semiconductor ZnGeP₂. The reference point for chemical potential (E_<i>f</i>) appears at the valence band maximum of high symmetry Γ point in Brillouin zone for ZnGeP₂. We report large bulk photovoltaic namely shift and circular photogalvanic current conductivities which are 4.46<i>µ</i>A V^-2and -5.49<i>µ</i>A V^-2respectively with the incident photo energy around ∼5 eV at the chemical potential of<i>E_f</i>= 0 eV which increase about 38% and 81% respectively at a chemical potential of<i>E_f</i>= 1.52 eV. The systematic evolution of the bulk Fermi surface along with the high symmetry points in three dimensional Brillouin zone reveals the enhancement of bulk photovoltaic with the chemical potential in ZnGeP₂. We further explore the distribution of bulk projected band and surface Fermi surface distribution in the energy landscape using tight binding Hamiltonian within semi infinite slab geometry. The augmentation of bulk photovoltaic with the chemical potential is due to the projected bulk bands along the high symmetryΓ-Zdirection in Brillouin zone. Our thorough and detailed study not only provide a deeper understanding about the role of Fermi surface contribution to the bulk photovoltaic responses with chemical potential, but also suggest ZnGeP₂as an ideal candidate for optoelectronics and bulk photovoltaic.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143523710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Ab initio</i>calculations of pressure and temperature dependent elastic constants of lead.","authors":"Camille Jacquelin, Etienne Jaupart, Vincent Dubois, Vanessa Riffet, Philippe Legrand, Laurianne Pillon","doi":"10.1088/1361-648X/adba2f","DOIUrl":"10.1088/1361-648X/adba2f","url":null,"abstract":"<p><p>In the framework of density functional theory, we present a methodology that is as<i>ab initio</i>as possible for calculating the elastic constants in pressure and temperature. In this context, elastic constants are derived via the strain-fluctuation formalism involving Born, kinetic and stress fluctuation terms.<i>ab initio</i>molecular dynamic trajectories in the isokinetic (NVT) ensemble are performed using the Abinit software to evaluate each term. Stress fluctuations are obtained directly from the trajectories. The Born term, on the other hand, is obtained by extracting several uncorrelated configurations from the trajectories and applying the energy-strain method. Bayesian inference is used to quantify the uncertainties associated with this procedure. As a result, the methodology enables elastic constants and their uncertainties to be evaluated for a wide range of materials. Admittedly, the whole approach has a high computational cost. In this paper, the method is then applied to solid lead in the fcc and hcp phases at various pressures and temperatures. The elastic constants obtained are linear as a function of temperature and pressure, and are qualitatively consistent with the experimental results available for the fcc phase. The major computational effort involved in obtaining a numerical<i>ab initio</i>reference database for lead can be used to test the accuracy of other approaches using surrogate models.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143502049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal transformations and dissociations in polycrystalline CO₂hydrates.","authors":"Xinheng Li, Yongxiao Qu, Yuan Li, Xiaoyu Shi, Kaibin Xiong, Zhisen Zhang, Jianyang Wu","doi":"10.1088/1361-648X/adbaa7","DOIUrl":"10.1088/1361-648X/adbaa7","url":null,"abstract":"<p><p>CO₂hydrates show promising application in CO₂sequestration, as well as natural gas recovering from hydrate-bearing sediments, in which the stability of CO₂hydrates plays a vital role in these practical applications. Here, we report the thermal dissociation and cage transformations in polycrystalline CO₂hydrates via high-throughput molecular dynamics simulations and machine learning (ML). It is revealed that the melting points of polycrystalline CO₂hydrates (PCO2H) are dictated by the microstructural cages, in which the 5¹², 5¹²6²and 4¹5¹⁰6³cages predominate. Upon heating, PCO2H shows reduction trend in the number of clathrate cages, while accompanied by large-scale cage reformations via 28 types of reversible/irreversible cage transformations. The cage transformations are achieved via mechanisms of removing, inserting and rotating water molecules, in which water molecules in clathrate cages substantially exchange. Cage transformations involve 5¹², 5¹²6², 4¹5¹⁰6³, and 4¹5¹⁰6²are pronouncedly frequent, acting as pivotal intermediate pathway in the thermal dissociation of PCO2H. The study provides a clear roadmap on the thermally-induced cage transformations and their mechanisms, and establishes ML frameworks to predict the dissociation behaviors in terms of melting points and melting dynamics.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Existence of a flat band in highly correlated metal BaCo₂P₂.","authors":"A Van Der Spuy, R Warmbier, Abhishek Pandey","doi":"10.1088/1361-648X/adb675","DOIUrl":"10.1088/1361-648X/adb675","url":null,"abstract":"<p><p>We report on the observation of a flat band situated at the Fermi levelEFalong with the structural, electrical transport, and magnetic properties of BaCo₂P₂that crystallizes in the ThCr₂Si₂-type body-center tetragonal structure. This compound has the largest inter-layer pnictide (<i>Pn</i>) distancedPn-Pnas well as the largestc/aratio among all the known<i>A</i>Co2Pn2(<i>A</i>= alkaline earth metal) compounds, where<i>a</i>and<i>c</i>are the tetragonal lattice parameters. Hence, the magnetic and electronic properties of this compound are expected to have a quasi-two-dimensional character. Despite the evidence of the presence of sizable magnetic interactions, magnetic susceptibilityχ(T)of BaCo₂P₂does not show magnetic ordering down to 1.8 K. The material shows good metallic conduction with a large residual resistivity ratioρ300K/ρ1.8K≈70and a Fermi liquid behavior at low temperature. Kadowaki-Woods ratioRKWof BaCo₂P₂suggests the presence of sizable electronic correlations within this system. Additionally, a large many-body enhancement of 2.3 of the experimental density of statesDγ(EF)over the band-structureDband(EF)is inferred to arise from sizable electron-electron and/or electron-phonon interactions leading to a substantial deviation from the free-electron behavior.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143425538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of varying laser energy density at LaScO₃/SrTiO₃interface.","authors":"Simran Nehra, Shikha Shrivastava, Sunil Gangwar, Pooja Manral, C S Yadav, V K Malik, Anjana Dogra","doi":"10.1088/1361-648X/adb922","DOIUrl":"10.1088/1361-648X/adb922","url":null,"abstract":"<p><p>The genesis of conductivity at the interface between two insulating perovskite oxides is the subject of rigorous investigation within the scientific community. The emergence of conductivity observed at the interface between insulating LaScO₃(LSO) and SrTiO₃(STO) is attributed to the phenomenon known as polar catastrophe. In this study, we fabricated LSO films on TiO₂-terminated STO substrates using the pulsed laser deposition technique. The investigation revealed a correlation between the film resistance and the variation in laser energy density during the deposition process, emphasizing the influence of energy density modulation on the electronic properties of the films. Also, the effect of cation non-stoichiometry in LSO films on mobility is examined and compared with the previously documented LAO/STO and LVO/STO interfaces.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Peering into interfaces in perovskite solar cells: a first-principles perspective.","authors":"Xu-Tong Liu, Jinshan Li, Xie Zhang","doi":"10.1088/1361-648X/adb9ad","DOIUrl":"10.1088/1361-648X/adb9ad","url":null,"abstract":"<p><p>Over the past decade, perovskite solar cells (PSCs) have experienced a rapid development. The remarkable increase in the photoelectric conversion efficiency demonstrates great promise of halide perovskites in the field of photovoltaics. Despite the excellent photovoltaic performance, further efforts are needed to enhance efficiency and stability. Interfacial engineering plays a crucial role in enhancing the efficiency and stability of PSCs, enabling champion cells to sustain a power conversion efficiency above 26% for over 1000 h. As a powerful theoretical tool for characterizing interfaces in PSCs, first-principles calculations have contributed to understanding interfacial properties and guiding the materials design. In this Perspective, we highlight the recent progress in theoretically profiling the interfaces between halide perovskites and other materials, focusing on the effects of energy band alignment and electronic structure on the carrier transport at the interfaces. These first-principles calculations help to reveal the atomic and electronic properties of the interfaces, and to provide important theoretical guidance for experimental research and device optimization. We also analyze potential strategies to enhance carrier separation and transport in PSCs, and discuss the challenges in accurate modeling interfaces in PSCs, which will help to understand the fundamental physics of interfaces in PSCs and to guide their further optimization.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492500","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of anisotropic confining potential and elliptical driving in dynamics of a Ge hole qubit.","authors":"Bashab Dey, John Schliemann","doi":"10.1088/1361-648X/adb927","DOIUrl":"10.1088/1361-648X/adb927","url":null,"abstract":"<p><p>The squeezing of a Ge planar quantum dot enhances the Rabi frequency of electric dipole spin resonance by several orders of magnitude due to a strong Direct Rashba spin-orbit interaction in such geometries (Bosco<i>et al</i>2021<i>Phys. Rev.</i>B<b>104</b>115425). We investigate the geometric effect of an elliptical (squeezed) confinement and its interplay with the polarization of driving field in determining the Rabi frequency of a heavy-hole qubit in a planar Ge quantum dot. To calculate the Rabi frequency, we consider only the<i>p</i>-linear SOIs viz. electron-like Rashba, hole-like Rashba and hole-like Dresselhaus which are claimed to be the dominant ones by recent studies on planar Ge heterostructures. We derive approximate analytical expressions of the Rabi frequency using a Schrieffer-Wolff transformation for small SOI and driving strengths. Firstly, for an out-of-plane magnetic field with magnitude<i>B</i>, we get an operating region with respect to<i>B</i>, squeezing and polarization parameters where the qubit can be operated to obtain 'clean' Rabi flips. On and close to the boundaries of the region, the higher orbital levels strongly interfere with the two-level qubit subspace and destroy the Rabi oscillations, thereby putting a limitation on squeezing of the confinement. The Rabi frequency shows different behaviour for electron-like and hole-like Rashba SOIs. It vanishes for right (left) circular polarization in presence of purely electron-like (hole-like) Rashba SOI in a circular confinement. For both in- and out-of-plane magnetic fields, higher Rabi frequencies are achieved for squeezed configurations when the ellipses of polarization and the confinement equipotential have their major axes aligned but with different eccentricities. We also deduce a simple formula to calculate the effective heavy hole mass by measuring the Rabi frequencies using this setup.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Photoemission spectroscopy and<i>ab-initio</i>simulation of CrFeVGa and CoFeVSb: a comparative study.","authors":"Jadupati Nag, Kritika Vijay, Barnabha Bandyopadhyay, Soma Banik, Aftab Alam, K G Suresh","doi":"10.1088/1361-648X/adb925","DOIUrl":"10.1088/1361-648X/adb925","url":null,"abstract":"<p><p>We present a comprehensive photoemission study of two Vanadium-based quaternary Heusler alloys, CrFeVGa and CoFeVSb, which are highly promising candidates for spintronics and topological quantum applications. CrFeVGa exhibits large anomalous Hall conductivity due to the large Berry curvature originating from its non-trivial topological bands. In contrast, CoFeVSb displays a spin-valve-like behavior alongside excellent thermoelectric properties, such as ultra-low thermal conductivity and high power factor at room temperature. By utilizing synchrotron x-ray photoemission spectroscopy and resonant photoemission spectroscopy, we have investigated the core levels and valence band of both the alloys. Our analysis shows that the V 3<i>d</i>states are primarily responsible for the electronic states at the Fermi level which result in the high spin polarization, consistent with our theoretical predictions. The presence of the Fermi edge in the valence band spectra in both the systems confirms the predicted metallic or half/semi-metallic features. The observed spectra match qualitatively with our simulated partial density of states. A close inspection of the temperature dependent valence band spectra indicates that some of the intriguing bulk properties reported earlier on these two systems are intimately connected with their unique band structure topology. This in turn facilitate a deeper insight into the origin of such interesting properties of these alloys. Such direct measurements of electronic structure provide a guiding platform towards a better understanding of the anomalous properties of any material in general.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143472499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}