Journal of Physics: Condensed Matter最新文献_第4页

Thermodynamics and entropic inference of nanoscale magnetic structures in Gd. 钆中纳米级磁结构的热力学和熵推断。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-14 DOI: 10.1088/1361-648X/ad92ee

Christian Binek, Syed Qamar Abbas Shah, Balamurugan Balasubramanian

{"title":"Thermodynamics and entropic inference of nanoscale magnetic structures in Gd.","authors":"Christian Binek, Syed Qamar Abbas Shah, Balamurugan Balasubramanian","doi":"10.1088/1361-648X/ad92ee","DOIUrl":"https://doi.org/10.1088/1361-648X/ad92ee","url":null,"abstract":"A bulk gadolinium (Gd) single crystal exhibits virtually zero remnant magnetization, a common trait among soft uniaxial ferromagnets. This characteristic is reflected in our magnetometry data showing virtually hysteresis free isothermal magnetization loops with large saturation magnetization. The absence of hysteresis allows to model the measured easy axis magnetization as a function of temperature and applied magnetic field, rather than a relation, which permits the application of Maxwell relations from equilibrium thermodynamics. Demagnetization effects broaden the isothermal first-order transition from negative to positive magnetization. By analyzing magnetization data within the coexistence regime, we deduce the isothermal entropy change and the field-induced heat capacity change. Comparing the numerically inferred heat capacity with relaxation calorimetric data confirms the applicability of the Maxwell relation. Analysis of the entropy in the mixed phase region suggests the presence of hitherto unresolved nanoscale magnetic structures in the demagnetized state of Gd. To support this prediction, Monte Carlo simulations of a 3D Ising model with dipolar interactions are performed. Analyzing the cluster size statistics and magnetization from the model provides strong qualitative support of our analytic approach.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622573","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}

引用次数: 0

Quantitative Eliashberg theory of the superconductivity of thin films. 薄膜超导的埃利亚斯伯格定量理论。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-14 DOI: 10.1088/1361-648X/ad92ed

Giovanni Alberto Ummarino, Alessio Zaccone

{"title":"Quantitative Eliashberg theory of the superconductivity of thin films.","authors":"Giovanni Alberto Ummarino, Alessio Zaccone","doi":"10.1088/1361-648X/ad92ed","DOIUrl":"https://doi.org/10.1088/1361-648X/ad92ed","url":null,"abstract":"A quantitative theory of the superconductivity of materials confined at the nanoscale in parameter-free agreement with experimental data has been missing so far.We present a generalization, in the Eliashberg framework, of a BCS theory of superconductivity in good metals which are confined along one of the three spatial directions, such as thin films. In this formulation of the Eliashberg equations the approximation of taking the normal density of states (DOS) as its value at the Fermi level has been removed. By numerically solving these new Eliashberg-type equations, we find the dependence of the superconducting critical temperature $T_{c}$ on the confinement size $L$, in quantitative agreement with experimental data of Pb and Al thin films with no adjustable parameters. This quantitative agreement provides an indirect confirmation that, upon increasing the confinement, a crossover from a spherical-like Fermi surface, which contains two growing hole pockets caused by the confinement, to a strongly deformed Fermi surface, occurs. This topology of the Fermi sea is implemented in the new Eliashberg-type equations to reproduce the experimentally observed maximum in the critical superconducting temperature vs film thickness of ultra-thin Pb films.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622570","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}

引用次数: 0

Impact of Cr doping on Hall resistivity and magnetic anisotropy in SrRuO3 thin films. 铬掺杂对 SrRuO3 薄膜霍尔电阻率和磁各向异性的影响

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-13 DOI: 10.1088/1361-648X/ad9212

Pooja Kesarwani, Santosh K Khetan, Brindaban Ojha, Ram Janay Choudhary, V R Reddy, Subhankar Bedanta, P S Anil Kumar, Chanchal Sow

{"title":"Impact of Cr doping on Hall resistivity and magnetic anisotropy in SrRuO3 thin films.","authors":"Pooja Kesarwani, Santosh K Khetan, Brindaban Ojha, Ram Janay Choudhary, V R Reddy, Subhankar Bedanta, P S Anil Kumar, Chanchal Sow","doi":"10.1088/1361-648X/ad9212","DOIUrl":"https://doi.org/10.1088/1361-648X/ad9212","url":null,"abstract":"Hall effects, including anomalous and topological types, in correlated ferromagnetic oxides provide an intriguing framework to investigate emergent phenomena arising from the interaction between spin-orbit coupling and magnetic fields. SrRuO3 is a widely studied itinerant ferromagnetic system with intriguing electronic and magnetic characteristics. The electronic transport of SrRuO3 is highly susceptible to the defects (O/Ru vacancy, chemical doping, ion implantation), and interfacial strain. In this regard, we investigate the impact of Cr doping on the magnetic anisotropy and the Hall effect in SrRuO3 thin films. The work encompasses a comprehensive analysis of the structural, spectroscopic, magnetic, and magnetotransport properties of Cr-doped SrRuO3 films grown on SrTiO3(001) substrates. Cross-sectional transmission electron microscopy reveals a sharp and coherent interface between the layers. Notably, perpendicular magnetic anisotropy is preserved in doped films with thicknesses up to 113 nm. The resistivity exhibits a T^2 dependence below the Curie temperature, reflecting the influence of disorder and correlation-induced localization effects. Interestingly, in contrast to the undoped parent compound SrRuO3, an anomaly in the Hall signal has been observed up to a large thickness (56 nm) attributed to the random Cr doping and Ru vacancy. Based on our measurements, a field-temperature (H -T) phase diagram of anomalous Hall resistivity is constructed.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622417","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}

引用次数: 0

Pairing phase favored by magnetic frustration. 配对相位受磁沮度的影响。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-13 DOI: 10.1088/1361-648X/ad922b

Arthur Krindges, Carlos Alberto Morais, Mateus Schmidt, Fabio M Zimmer

{"title":"Pairing phase favored by magnetic frustration.","authors":"Arthur Krindges, Carlos Alberto Morais, Mateus Schmidt, Fabio M Zimmer","doi":"10.1088/1361-648X/ad922b","DOIUrl":"https://doi.org/10.1088/1361-648X/ad922b","url":null,"abstract":"The interplay between magnetic frustration and pairing is investigated by adopting a BCS-like pairing mechanism on the frustrated $J_1-J_2$ Ising model on the square lattice. The ground-state and thermal phase transitions of the model are analyzed using a fermionic formulation within a cluster mean-field method. In this approach, the lattice system is divided into identical clusters, where the intracluster dynamic is exactly solved, and the intercluster interactions are replaced by self-consistent mean fields. We introduce a framework with two pairing couplings: an intracluster local coupling, $g$, which controls the electron pairing and its mobility within the clusters, and an intercluster coupling, $g'$, which adjusts the pairing mechanism between clusters. Tuning $g'/g$ allows evaluating how the pairing phase evolves from a weak pairing coupling between clusters (clustered system) to a strong one ($g' rightarrow g$, homogeneous system). In the range $0 le g'/g le 1$, we find that a gradual increase in $g'/g$ favors the pairing phase and induces a change in criticality. In particular, our results reveal the presence of tricriticality for a certain range of $g'/g$. In addition, an increase in competing magnetic interactions weakens the magnetic orders, causing the pairing phase to occur at lower strengths of pairing interactions, especially when $g' = g$. Therefore, our findings support that magnetic frustration favors the pairing phase, contributing to the onset of a superconducting state.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622555","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}

引用次数: 0

Interface phonon transport in nanomaterials: numerical methods and modulation strategies. 纳米材料中的界面声子传输：数值方法和调制策略。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-13 DOI: 10.1088/1361-648X/ad9210

Yuan Yao, Hao Chen, Zhong-Ke Ding, Wei-Hua Xiao, Nannan Luo, Jiang Zeng, Li-Ming Tang, Ke-Qiu Chen

{"title":"Interface phonon transport in nanomaterials: numerical methods and modulation strategies.","authors":"Yuan Yao, Hao Chen, Zhong-Ke Ding, Wei-Hua Xiao, Nannan Luo, Jiang Zeng, Li-Ming Tang, Ke-Qiu Chen","doi":"10.1088/1361-648X/ad9210","DOIUrl":"https://doi.org/10.1088/1361-648X/ad9210","url":null,"abstract":"The thermal properties of interfaces in nanomaterials are critical for various technological applications, including thermal management in electronic and photonic devices, thermoelectric conversion and thermal insulation. Recent advancements in numerical simulation tools (the non-equilibrium Green's approach, the Boltzmann transport equation and the Monte Carlo method, molecular dynamics simulations) have significantly enhanced our understanding of phonon transport and scattering processes in nanomaterials. These advances have led to the discovery of new thermal interfacial materials and enabled precise modulation of phonon thermal conductance to achieve desired thermal performance. This review summarizes recent research progress in interface thermal transport, focusing on intriguing heat phenomena such as finite size effect and phonon coherent property. Additionally, it discusses strategies for modulating thermal conductance through disorder and roughness. Finally, the review proposes the opportunities and challenges associated with modulating interface thermal transport.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622506","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}

引用次数: 0

Enhanced energy storage performance inBaZrxTi1-xO3 lead-free ferroelectrics near phase transitions. 增强 BaZrxTi1-xO3 无铅铁电体在相变附近的储能性能。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-13 DOI: 10.1088/1361-648X/ad9211

Ba-Hieu Vu, Ha Thi Dang, Van-Hai Dinh, Lich Van Le

{"title":"Enhanced energy storage performance inBaZrxTi1-xO3 lead-free ferroelectrics near phase transitions.","authors":"Ba-Hieu Vu, Ha Thi Dang, Van-Hai Dinh, Lich Van Le","doi":"10.1088/1361-648X/ad9211","DOIUrl":"https://doi.org/10.1088/1361-648X/ad9211","url":null,"abstract":"The present study explores the energy storage properties of BaZrxTi1-xO3 through phase-field modeling, focusing on the impact of composition and temperature on energy storage performance. The obtained results reveal a variety of polarization phases and configurations based on Zr compositions and temperatures. A detailed phase diagram for temperature-composition of BaZrxTi1-xO3 is established, closely aligning with experimental measurements. Variations in Zr content and temperature have a significant impact on the polarization-electric field response, influencing the energy storage properties. Calculations of energy storage properties are derived from the polarization-electric field response. In addition, a thorough diagram is developed to illustrate the discharge energy density of BaZrxTi1-xO3 as a function of temperature and composition. Notably, high discharge energy density is achievable near the Curie temperature, corresponding to the transition from ferroelectric to paraelectric phase. Furthermore, the present study emphasizes the importance of the disparity between maximum and remanent polarization, as well as the electric field-dependent effective permittivity, in determining the discharge energy density.&#xD.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142622406","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}

引用次数: 0

Composite quadrupole order in ferroic and multiferroic materials. 铁性和多铁性材料中的复合四极秩序。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-12 DOI: 10.1088/1361-648X/ad8ea3

R Matthias Geilhufe

引用次数: 0

Charge transfer induced phase transition in Li₂MnO₃at high pressure. 高压下 Li2MnO3 中电荷转移诱导的相变。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-12 DOI: 10.1088/1361-648X/ad8b8f

Ajinkya P Khangal, Nishant N Patel, Ajay K Mishra

{"title":"Charge transfer induced phase transition in Li2MnO3at high pressure.","authors":"Ajinkya P Khangal, Nishant N Patel, Ajay K Mishra","doi":"10.1088/1361-648X/ad8b8f","DOIUrl":"10.1088/1361-648X/ad8b8f","url":null,"abstract":"Efficient and better energy storage materials are of utmost technological importance to reduce energy dependence on the fossil fuels. Li2MnO3is one such material having potential to meet most of the requirements for energy storage. This material has been synthesized using solid state synthesis route. High pressure structural and vibrational studies on this material have been carried out upto ∼22 and 26 GPa respectively. These investigations show occurrence of a hitherto unknown second order phase transition to a new low symmetry phase whose symmetry is constrained to be monoclinic with space group P21/n at pressure of ∼2.3 GPa in Li2MnO3. The bulk modulus and its derivative determined by fitting theP-Vdata with third order Birch-Murnaghan equation of state are 113.3 ± 13.1 GPa and 4.1 ± 1.2 respectively. Mode Grüneisen parameter calculated for all the Raman modes show positive values which indicates the absence of any soft mode in this material. A microscopic mechanism based on bond-charge transfer is invoked and applied to understand the spectroscopic changes occurring in this material which also manifests second order structural phase transition. Enhancement in covalent character of Li-O bonds in the Li-O polyhedra is inferred based on the spectroscopic observation and above mechanism.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142502583","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}

引用次数: 0

Magnetic order in nanogranular iron germanium (Fe_0.53Ge_0.47) films. 纳米粒状铁锗（Fe0.53Ge0.47）薄膜中的磁序。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-12 DOI: 10.1088/1361-648X/ad8c0a

Ruthi Zielinski, Nhat Nguyen, Bryce Herrington, Amir Tarkian, Omar Taha, Wai Kiat Chin, Ather Mahmood, Xiaoqian Chen, Christoph Klewe, Padraic Shafer, Jim Ciston, Paul Ashby, Claudio Mazzoli, Robert Streubel

引用次数: 0

From weak- to strong-coupling superconductivity in the AlB₂-type solid solution SrGa_1-xAl_xGe with honeycomb layers. 具有蜂巢层的 AlB2 型固溶体 SrGa1-xAlxGe 中从弱耦合到强耦合的超导性。

IF 2.3 4区物理与天体物理

Journal of Physics: Condensed Matter Pub Date : 2024-11-12 DOI: 10.1088/1361-648X/ad8c0b

Dorota I Walicka, Olivier Blacque, Tomasz Klimczuk, Fabian O von Rohr

{"title":"From weak- to strong-coupling superconductivity in the AlB2-type solid solution SrGa1-xAlxGe with honeycomb layers.","authors":"Dorota I Walicka, Olivier Blacque, Tomasz Klimczuk, Fabian O von Rohr","doi":"10.1088/1361-648X/ad8c0b","DOIUrl":"10.1088/1361-648X/ad8c0b","url":null,"abstract":"We report on the structure and the superconducting properties of 9-electron 111 compounds with honeycomb layers, namely SrGaGe, SrAlGe, and the SrGa1-xAlxGe solid solution. By means of single-crystal x-ray diffraction we show that, on one hand, SrGaGe crystallizes into the centrosymmetricP6/mmmspace group (a= 4.2555(2) Å,c= 4.7288(2) Å) with statistical disorder in the [GaGe]62-honeycomb layers. On the other hand, we confirm that SrAlGe crystallizes in a non-centrosymmetric space group, namelyP6¯m2(a= 4.2942(1) Å,c= 4.7200(2) Å) with fully ordered [AlGe]62-honeycomb layers. By using magnetization and specific heat measurements, we show that the superconducting properties of SrGaGe and SrAlGe differ significantly from each other. SrGaGe is a superconductor with a critical temperature ofTc= 2.6 K falling into the weak coupling limit, while SrAlGe has aTc= 6.7 K and can be classified in the strong coupling limit. By realizing the SrGa1-xAlxGe solid solution, we were able to investigate the transition between the different crystal structures as well as the evolution of the electronic properties. We show that the transition from the weak-to strong-coupling superconductivity in this system is likely associated with the disorder-to-order transition of the honeycomb layer, along with the loss of the inversion center in the crystal structure.","PeriodicalId":16776,"journal":{"name":"Journal of Physics: Condensed Matter","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142522207","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}

引用次数: 0