Journal of Physics: Condensed Matter最新文献

{"title":"Possible structures of skyrmion states in chiral ferromagnetic films with spatially modulated uniaxial anisotropy.","authors":"Robert M Vakhitov, Aigul Alfredovna Akhmetova, Mikhail Aleksandrovich Filippov","doi":"10.1088/1361-648X/ad8ea1","DOIUrl":"https://doi.org/10.1088/1361-648X/ad8ea1","url":null,"abstract":"<p><p>In this paper, the stabilization conditions, structure, and properties of possible vortex-like inhomogeneities, including kπ-skyrmions k = 0, 1, 2, 3, 4, in a uniaxial multilayer disk with a columnar defect in the center are investigated based on micromagnetic modeling. Their stability diagrams depending on the Dzyaloshinskii-Moriya interaction, the magnitude of magnetic anisotropy and the defect parameters are determined. New types of vortex-like inhomogeneities that can arise in such samples are found. The obtained data can be used to create artificial regions of nucleation, capture and pinning of magnetic skyrmions, which can provide greater reliability of data storage in spintronic logical devices.&#xD.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142576305","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":"Charge-driven first-order magnetic transition in NiPS₃.","authors":"Junik Hwang, Seonghoon Park, Beom Hyun Kim, Junghyun Kim, Je-Geun Park, Seung-Ho Baek","doi":"10.1088/1361-648X/ad8ea0","DOIUrl":"https://doi.org/10.1088/1361-648X/ad8ea0","url":null,"abstract":"<p><p>Cross-coupling among the fundamental degrees of freedom in solids has been a long-standing problem in condensed matter physics. Despite its progress using predominantly three-dimensional materials, how the same physics plays out for two-dimensional materials is unknown. Here, we show that using³¹P nuclear magnetic resonance (NMR), the van der Waals antiferromagnet NiPS₃undergoes a first-order magnetic phase transition due to the strong charge-spin coupling in a honeycomb lattice. Our³¹P NMR spectrum near the N´eel ordering temperature T_N= 155 K exhibits the coexistence of paramagnetic and antiferromagnetic phases within a finite temperature range. Furthermore, we observed a discontinuity in the order parameter at T_Nand the complete absence of critical behavior of spin fluctuations above T_N, decisively establishing the first-order nature of the magnetic transition. We propose that a charge stripe instability arising from a Zhang-Rice triplet ground state triggers the first-order magnetic transition.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142576301","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 and structural analysis of binary mixtures of pyrimidine liquid crystals using Modulated Differential Calorimetry and Synchrotron X-ray Diffraction measurements.","authors":"Smriti Mitra, Akhileshwar Prasad, Malay Kumar Das, Banani Adhikari Das, Anuj Upadhyay, Archana Sagdeo, A Yogi","doi":"10.1088/1361-648X/ad8e26","DOIUrl":"https://doi.org/10.1088/1361-648X/ad8e26","url":null,"abstract":"<p><p>We present a systematic experimental dataset on the temperature dependence of specific heat capacity in a binary mixture of the second and seventh homologous series of 5-alkyloxy-2-(4-nonyloxy-phenyl) pyrimidine(PhP) liquid crystal compound. These binary mixtures exhibit nematic, smectic-A, and smectic-C phases within a concentration range of xPhP1 = 0 to 0.45. The liquid crystalline phases are structurally characterized using synchrotron X-ray diffraction. We determine the apparent molecular length in the nematic phase, smectic layer spacing, average distance between the long axes of molecules, correlation length, and orientational order parameters (<P2> and <P4>) as functions of temperature. The tilt angle in the SmC phase is inferred from the layer spacing data. To examine the critical behavior near the nematic to smectic A(NA) and smectic A to the smectic C (AC) phase transitions, we evaluate the critical exponents: α from specific heat capacity, β from the fitting of the temperature-dependent tilt angle, and ν_‖, ν_⊥from the temperature-dependent longitudinal (ξ_‖) and transverse (ξ_⊥) correlation lengths. Modulated Differential Scanning Calorimetry (MDSC) measurements indicate the absence of phase shift, latent heat and imaginary specific heat capacity, suggesting that the AC transitions are second-order for all binary mixtures. The results obtained from heat capacity reveal that both the AC and NA transitions exhibit non-universal behaviours with effective exponents lying between the tricritical and 3D-XY values and follow nearly identical curve with decreasing width of the Sm-A and N phases. The Josephson hyperscaling relation is verified for both the NA and AC transitions in different mixtures. Moreover, knowing the heat capacity critical exponent α and the order parameter critical exponent β, the susceptibility critical exponent γ for the AC transition can be estimated from Rushbrooke equality α+2β+γ=2, with γ values ranging from 1.015 to 1.313, indicating the system's crossover character and apparently validating the Rushbrooke equality.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142564242","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":"Electronic states bound by repulsive potentials in graphene irradiated by a circularly polarized electromagnetic field.","authors":"O V Kibis, M V Boev, I V Iorsh, V M Kovalev","doi":"10.1088/1361-648X/ad88c5","DOIUrl":"10.1088/1361-648X/ad88c5","url":null,"abstract":"<p><p>In the framework of the Floquet theory of periodically driven quantum systems, it is demonstrated that irradiation of graphene by a circularly polarized electromagnetic field induces an attractive area in the core of repulsive potentials. Consequently, the quasi-stationary electron states bound by the repulsive potentials appear. The difference between such field-induced states in graphene and usual systems with the parabolic dispersion of electrons is discussed and possible manifestations of these states in electronic transport and optical spectra of graphene are considered.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468289","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":"Recent advances in understanding and manipulating magnetic and electronic properties of Eu<i>M</i>₂<i>X</i>₂(<i>M</i>= Zn, Cd;<i>X</i>= P, As).","authors":"Xiyu Chen, Shuai Dong, Zhi-Cheng Wang","doi":"10.1088/1361-648X/ad882b","DOIUrl":"10.1088/1361-648X/ad882b","url":null,"abstract":"<p><p>Over the past five years, significant progress has been made in understanding the magnetism and electronic properties of CaAl₂Si₂-type Eu<i>M</i>₂<i>X</i>₂(<i>M</i>= Zn, Cd;<i>X</i>= P, As) compounds. Prior theoretical work and experimental studies suggested that EuCd₂As₂had the potential to host rich topological phases, particularly an ideal magnetic Weyl semimetal state when the spins are polarized along the<i>c</i>axis. However, this perspective is challenged by recent experiments utilizing samples featuring ultra-low carrier densities, as well as meticulous calculations employing various approaches. Nonetheless, the Eu<i>M</i>₂<i>X</i>₂family still exhibit numerous novel properties that remain to be satisfactorily explained, such as the giant nonlinear anomalous Hall effect and the colossal magnetoresistance effect. Moreover, Eu<i>M</i>₂<i>X</i>₂compounds can be transformed from semiconducting antiferromagnets to metallic ferromagnets by introducing a small number of carriers or applying external pressure, and a further increase in the ferromagnetic transition temperature can be achieved by reducing the unit cell volume. These features make the Eu<i>M</i>₂<i>X</i>₂family a fertile platform for studying the interplay between magnetism and charge transport, and an excellent candidate for applications in spintronics. This paper presents a comprehensive review of the magnetic and transport behaviors of Eu<i>M</i>₂<i>X</i>₂compounds with varying carrier densities, as well as the current insights into these characteristics. An outlook for future research opportunities is also provided.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468305","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":"Theoretical insights into off-stoichiometric Zr_(x)Ti_(1-x)IrSb half-Heusler alloys: a first principle calculations.","authors":"Mohammed Hadbi, Kamel Demmouche, Djallal Eddine Mellah, Jose Coutinho","doi":"10.1088/1361-648X/ad899b","DOIUrl":"10.1088/1361-648X/ad899b","url":null,"abstract":"<p><p>This study presents a theoretical investigation into the phase stability, electronic, and optical properties of off-stoichiometricZrxTi1-xIrSb(<i>x</i>= 0, 0.0625, 0.1875, 0.25, 0.50, 0.75, 1) compounds. Using first-principles calculations, we explore how varying Zr and Ti concentrations can tune the electronic and optical properties of these half-Heusler alloys. The Structural, optical, and electronic properties were meticulously analyzed with both the GGA-PBE and Meta-GGA-SCAN approximations, as implemented in the Vienna<i>Ab initio</i>Simulation Package (VASP). The dynamical stability of these compounds was assessed using the Phonopy package. Our findings reveal that these alloys exhibit semiconductor behavior with tunable band gaps, and their optical properties show significant variation across different compositions, particularly in the visible light range. The compounds also demonstrate robust dynamical stability, indicating their potential for practical applications in electronic and optoelectronic devices. These results underscore the versatility ofZrxTi1-xIrSballoys and highlight their promise for next-generation technology.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468308","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":"Electronic, optical and thermoelectric behavior of KCuX (X = S, Se, Te) monolayers.","authors":"Neelam Gupta, Shubham Kumar, Shivani Rani, Puja Kumari, Subhasmita Kar, Rajeev Ahuja, Soumya Jyoti Ray","doi":"10.1088/1361-648X/ad84a8","DOIUrl":"10.1088/1361-648X/ad84a8","url":null,"abstract":"<p><p>In the past few decades, two-dimensional materials gained huge deliberation due to their outstanding electronic and heat transport properties. These materials have effective applications in many areas such as photodetectors, battery electrodes, thermoelectrics, etc. In this work, we have calculated structural, electronic, optical, and thermoelectric (TE) properties of KCuX (X = S, Se, Te) monolayers (MLs) with the help of first-principles-based calculations and semi-classical Boltzmann transport equation. The phonon dispersion calculations demonstrate the dynamical stability of the KCuX (X = S, Se, Te) MLs. Our results show that the MLs of KCuX (X = S, Se, Te) are semiconductors with band gaps of 0.193 eV, 0.26 eV, and 1.001 eV respectively, and therefore they are suitable for photovoltaic applications. The optical analysis illustrates that the maximum absorption peaks of the KCuX (X = S, Se, Te) MLs are located in the visible and ultraviolet regions, which may serve as a promising candidate for designing advanced optoelectronic devices. Furthermore, thermoelectric properties of the KCuS and KCuSe MLs, including Seebeck coefficient, electrical conductivity, electronic thermal conductivity, power factor and figure of merit are calculated at different temperatures of 300 K, 600 K, and 800 K. Additionally, we also focus on the analysis of Grüneisen parameter and various scattering rates to further explain their ultra-low thermal conductivity. Our results show that KCuS and KCuSe possess ultra-low lattice thermal conductivity value of 0.15Wm-1K-1and 0.06Wm-1K-1respectively, which is lower than those of recently reported KAgSe (0.26Wm-1K-1at 300 K) and TlCuSe (0.44Wm-1K-1at 300 K), indicating towards the large value of ZT. These materials are found to possess desirable thermoelectric and optical properties, making them suitable candidates for efficient thermoelectric and optoelectronic device applications.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142391363","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":"Multiplet XPS analysis of the Mn 2<i>p</i>for Mn₃O₄thin films.","authors":"Jade Barreto, Paul S Bagus, Fernando Stavale","doi":"10.1088/1361-648X/ad8b91","DOIUrl":"10.1088/1361-648X/ad8b91","url":null,"abstract":"<p><p>In this work, we performed a detailed analysis of the x-ray photoemission spectroscopy (XPS) of the Mn 2<i>p</i>peak for Mn₃O₄(001) thin films. This is a challenging task since Mn₃O₄is composed of two different cations, Mn²⁺at tetrahedral and Mn³⁺at octahedral sites, which both contribute to the XPS spectra. The oxide spectra consist of many multiplets arising from the angular momentum coupling of the open Mn 2<i>p</i>and 3<i>d</i>shells, thus increasing the spectrums' complexity. Moreover, the energy spacing and intensities of the different multiplets also reflect the covalent mixing between Mn 3<i>d</i>and O 2<i>p</i>shells. However, we show that a detailed analysis, which provides relevant information about the cations in the oxide structure, is possible. We prepared experimentally different Mn₃O₄films on Au(111), and their structure was monitored with the diffraction pattern obtained with low-energy electron diffraction. The Mn 2<i>p</i>spectra were fit, guided by cluster model theoretical predictions, and checked for films prepared at different oxygen partial pressures. Therefore, we could observe the Mn²⁺and Mn³⁺cations' relative concentration in the Mn 2<i>p</i>mains peaks.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142502596","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":"Ultrafast structural transition and electron-phonon/phonon-phonon coupling in antimony revealed by nonadiabatic molecular dynamics.","authors":"Meng Niu, Shun-Yao Qin, Bai-Qian Wang, Nian-Ke Chen, Xian-Bin Li","doi":"10.1088/1361-648X/ad8696","DOIUrl":"10.1088/1361-648X/ad8696","url":null,"abstract":"<p><p>Real-time time-dependent density-functional theory molecular dynamics (rt-TDDFT-MD) reveals the nonadiabatic dynamics of the ultrafast photoinduced structural transition in a typical phase-change material antimony (Sb) with Peierls distortion (PD). As the excitation intensity increases from 3.54% to 5.00%, three distinct structural transition behaviors within 1 ps are observed: no PD flipping, nonvolatile-like PD flipping, and nonstop back-and-forward PD flipping. Analyses on electron-phonon and phonon-phonon couplings indicate that the excitation-activated coherent A_1gphonon mode by electron-phonon coupling drives the structural transition within several hundred femtoseconds. Then, the energy of coherent motions are transformed into that of random thermal motions via phonon-phonon coupling, which prevents the A_1g-mode-like coherent structure oscillations. The electron-phonon coupling and coherent motions will be enhanced with increasing the excitation intensity. Therefore, a moderate excitation intensity that can balance the coherent and decoherent thermal movements will result in a nonvolatile-like PD flipping. These findings illustrate important roles of nonadiabatic electron-phonon/phonon-phonon couplings in the ultrafast laser-induced structural transitions in materials with PD, offering insights for manipulating their structures and properties by light.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142468312","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":"Ultralow magnetic susceptibility in pure and Fe(Bi)-doped Au-Pt alloys improved by structural strain regulation.","authors":"Jun-Tao Ma, Ye-Lei Xiao, Butian Zhang, Shun Wang, Ze-Bing Zhou, Hua-Hua Fu","doi":"10.1088/1361-648X/ad8ab8","DOIUrl":"10.1088/1361-648X/ad8ab8","url":null,"abstract":"<p><p>Designing and manufacturing multi-component alloy samples with ultralow magnetic susceptibility<i>χ</i>(<10^-6cm³mol^-1) is crucial for producing high-quality test masses to successfully detect gravitational wave in the LISA and TianQin projects. Previous research has idenfified AuPt alloys as a potential candidate for test masses, capable of achieving ultralow magnetic susceptibility that meets the requirements from both theoretical and experimental perspectives. In this study, we discover that the structural strain regulation (i.e. tensile and stress) can effectively optimize and further reduce the ultralow magnetic susceptibility of AuPt allpys, while fully understanding their underlying physical mechanisms. More importantly, even when doped with trace elements such as Fe or Bi impurity, strain regulation can still effectively reduce the magnetic susceptibility of the doped AuPt alloy to the desired range. Our theoretical calculations also reveal that, when the strain ratio<i>η</i>is controlled within in a relatively small range (<2.0%), the regulaton effect on the ultralow magnetic susceptibilities of pure or doped-AuPt alloys remains significant. This property is beneficial for achieving ultralow or even near-zero magnetic susceptibility in real AuPt alloy samples.</p>","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":null,"pages":null},"PeriodicalIF":2.3,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142502598","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}