Journal of Superconductivity and Novel Magnetism最新文献

{"title":"Synthesis and Electron Spin Resonance Study of Zn0.7Ni0.3RE0.1Fe1.9O4 (RE = Gd, Sm, Dy) Nanostructured Ferrites","authors":"S. J. C. Masuku,&nbsp;J. Z. Msomi,&nbsp;T. S. Mahule,&nbsp;V. V. Srinivasu","doi":"10.1007/s10948-025-06932-9","DOIUrl":"10.1007/s10948-025-06932-9","url":null,"abstract":"<div><p>The glycol-thermal technique synthesized Zn_0.7Ni_0.3RE_0.1Fe_1.9O₄ (RE = 0, Gd, Sm, Dy) nanostructured ferrites with fine particles in the 8–13 nm range. X-ray diffraction (XRD) data confirmed a single-phase cubic spinel structure with no impurity peaks for the samples investigated. High-resolution transmission electron microscopy (HrTEM) showed nearly spherical particle images for the pure Zn_0.7Ni_0.3Fe₂O₄. HrTEM images for Zn_0.7Ni_0.3RE_0.1Fe_1.9O₄ (RE = Gd, Sm, or Dy) rare-earth-substituted fine particles revealed agglomerated particles with irregular shapes. Reduced particle sizes of rare-earth-substituted Zn-Ni compared to undoped compounds have been explained based on electron–electron repulsion of 4f electrons. Electron spin dynamics were investigated by electron spin resonance (ESR) measurements. A broad ESR signal with the highest intensity has been observed for the Sm-doped compound (Zn_0.7Ni_0.3Sm_0.1Fe_1.9O₄) with a particle size of about 8 nm. Broadening of the signal revealed stronger magnetic dipole interactions and narrower signals for Gd- and Dy-doped compounds indicate stronger superexchange interactions. The slightest ESR signal observed for the Gd-based (Zn_0.7Ni_0.3Gd_0.1Fe_1.9O₄) compound has been attributed to high spin–orbit coupling and the paramagnetic nature of Gd ions disrupting magnetic resonance. The evolution of the magnetic parameters, such as signal line width, intensities, and <i>g</i>-factors, as a function of the type of rare-earth ions, has been presented and correlated with the outer 4f electron number of rare-earth ions and particle size. Rare-earth-doped Zn_0.7Ni_0.3RE_0.1Fe_1.9O₄ (RE = Gd, Sm, Dy) nanostructured ferrites exhibit enhanced magnetic and structural properties, critical for advanced applications such as magnetic separation and biomedical imaging. This study demonstrates the influence of rare-earth doping on ESR parameters, particle size, and magnetization, providing insights into the role of 4f electron configurations.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10948-025-06932-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143466021","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"X-Ray Computed Tomography Study of the Microstructure of Superconducting MgB2 Bulks","authors":"Yingqing Wang,&nbsp;Chris Grovenor,&nbsp;Susannah Speller,&nbsp;Barbara Shollock,&nbsp;Tayebeh Mousavi","doi":"10.1007/s10948-025-06933-8","DOIUrl":"10.1007/s10948-025-06933-8","url":null,"abstract":"<div><p>MgB₂ is a promising candidate for commercial superconducting applications because, as grain boundaries in MgB₂ are not weak links, there are fewer limitations on the choice of processing technique compared to high-temperature superconducting (HTS) cuprates. MgB₂ bulks are usually manufactured by powder processing techniques followed by a sintering process. After sintering, the impurity phases such as MgO and MgB₄ along with porosity are formed which strongly affect the superconducting properties mainly the macroscopic path for supercurrent in MgB₂ bulks. Investigation of these microstructural features is essential to improve the superconducting properties of these bulks. In this work, high-resolution laboratory X-ray computed tomography (XCT) has been used to investigate the microstructure of MgB₂ bulks in three dimensions. The volume fraction of defects and impurity phases along with the size distribution of pores have been studied using this advanced technique. A comparison has been made between the data extracted from conventional characterization techniques such as XRD and SEM and those obtained from the advanced XCT analysis.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10948-025-06933-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430942","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-Frequency Magnetoimpedance Effect in Five-Layer Nanostructured Thin Film: Magnetostatic Coupling in Symmetric Structure","authors":"Jintao Liu,&nbsp;Tao Wang,&nbsp;Jinbo Chen,&nbsp;Hengyu Li,&nbsp;Zhizheng Wu,&nbsp;Ze Cui,&nbsp;Mei Liu","doi":"10.1007/s10948-025-06924-9","DOIUrl":"10.1007/s10948-025-06924-9","url":null,"abstract":"<div><p>In the field of high-frequency magnetic impedance (MI) research, accurately describing the MI effect in multilayer nanostructured thin films remains a challenging task. A model to accurately describe high-frequency magnetoimpedance in the FeNi/Co/Cu/Co/FeNi five-layer nanostructured thin film is developed. The GMI response was obtained through the simultaneous solution of Maxwell’s equations and the Landau-Lifshitz equation. Through the induction of an effective bias field in the soft magnetic layer, the magnetostatic coupling between the soft and hard magnetic layers is taken into account. At frequencies up to GHz magnitude, symmetrically structured nanofilms are capable of obtaining a greater MI ratio through magnetic coupling. Furthermore, we demonstrate that modifying film properties and manipulating the bias field can lead to improved sensing performance. This study not only fills the gap in the theoretical model of five-layer nanostructured symmetrical films but also provides a theoretical foundation for the design and optimization of high-performance magnetic sensors operating at high frequencies. The findings presented in this paper hold potential to advance the development of high-frequency magnetic impedance sensors.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 2","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143423051","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":"A Comparative Study of Diffusion Sources for Improved Magnetic Properties of NdFeB Magnets","authors":"Xi Yu,&nbsp;Sangen Luo,&nbsp;Shengwu Shen,&nbsp;Honglong Yang,&nbsp;Munan Yang,&nbsp;Shuwei Zhong,&nbsp;Bin Yang","doi":"10.1007/s10948-025-06925-8","DOIUrl":"10.1007/s10948-025-06925-8","url":null,"abstract":"<div><p>This study focuses on sintered NdFeB magnets and systematically examines the diffusion behavior and its impact on magnetic properties using three types of diffusion sources: DyF₃ powder, a mixed powder of DyF₃ and Pr₇₀Co₁₅Al₁₅ alloy, and Pr₆₀Dy₁₀Co₁₅Al₁₅ alloy powder. The findings demonstrate that the Pr₆₀Dy₁₀Co₁₅Al₁₅ alloy diffusion source produces the most favorable outcomes, with an enhancement in coercivity by 6.9 kOe. The composite diffusion source demonstrates a 5.83-kOe increase, while the fluoride diffusion source exhibits the least improvement, with a 4.21-kOe increase. The diffusion of DyF₃ is constrained by its high decomposition temperature and interference from F elements, which limit the depth of diffusion of Dy. The composite diffusion source, through the liquid-phase diffusion of Pr₇₀Co₁₅Al₁₅ alloy, has the effect of improving the wettability of grain boundaries and the channels of diffusion, which significantly increases the depth of diffusion of Dy elements. In the Pr₆₀Dy₁₀Co₁₅Al₁₅ alloy diffusion source, the synergistic diffusion of Dy, Pr, and Al elements enhances diffusion efficiency. Moreover, extending the diffusion time allows for further optimization of the grain boundary structure, thus facilitating deeper diffusion of Dy elements. This study thus demonstrates the superiority of the Pr₆₀Dy₁₀Co₁₅Al₁₅ alloy diffusion source, providing a crucial foundation for the efficient use of rare earth resources and the development of high-performance magnets.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404131","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":"Research Progress of High Efficiency Magnetic Refrigeration Technology and Magnetic Materials","authors":"Yujia Wang,&nbsp;Haodan Pan,&nbsp;Shuo Liu","doi":"10.1007/s10948-024-06847-x","DOIUrl":"10.1007/s10948-024-06847-x","url":null,"abstract":"<div><p>As an environmentally friendly and efficient refrigeration method, magnetic refrigeration technology has always attracted the attention of researchers. In this paper, the research and development status of magnetic refrigeration technology and magnetic materials are discussed in depth, and the challenges faced by the technology are also evaluated. Firstly, the principle of magnetic refrigeration technology is introduced, and the research and development process and current development of room-temperature and low-temperature magnetic refrigeration systems are briefly described. Then, the simulation of magnetic refrigeration technology in the current era is discussed in detail, and the important role of calculation model in optimizing system design is emphasized. Secondly, this paper reviews the classification of magnetic refrigeration materials, including room-temperature magnetic refrigeration materials and low-temperature magnetic refrigeration materials, and further analyzes the current research process of magnetic refrigeration materials. Through the comparative analysis of different materials, find out the most suitable magnetocaloric materials. Finally, this paper not only summarizes the current situation of magnetic refrigeration technology, but also makes a prospect for the future development of magnetic refrigeration technology and magnetic materials. Through the in-depth elaboration and analysis of this review paper, it aims to provide theoretical and practical guidance for the further advancement of magnetic refrigeration and magnetic materials research.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143404242","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":"Magnetic AC Susceptibility and Relaxation Processes in Y- And Bi-Doped Rare Earth Holmium Titanates","authors":"O. V. Nemytova,&nbsp;A. B. Rinkevich,&nbsp;D. V. Perov,&nbsp;M. S. Koroleva,&nbsp;I. V. Piir","doi":"10.1007/s10948-025-06923-w","DOIUrl":"10.1007/s10948-025-06923-w","url":null,"abstract":"<div><p>The work is devoted to the study of the magnetic DC and AC susceptibilities, as well as to the analysis of spin dynamics (relaxation processes) of yttrium- and bismuth-doped rare earth holmium titanates. An influence of doping degree and the type of dopant on the magnetic properties of holmium titanates have been evaluated. The magnetization curves were measured. The measurement of frequency dependence of the AC susceptibility allowed us to analyze spin dynamics and estimate characteristic magnetic relaxation times in the studied systems.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143379744","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":"Calculation Electronic Structure and Topological Properties of A15-Type Mo3Si Based on First-Principles Predictions","authors":"Hanqi Zhou,&nbsp;Li Zhang","doi":"10.1007/s10948-025-06929-4","DOIUrl":"10.1007/s10948-025-06929-4","url":null,"abstract":"<div><p>Superconductors with the A15 structure are prototypical type II s-wave superconductors which have generated considerable interest in early superconducting material history. However, the topological properties of the electronic structure remain unnoticed. In this study, we used first-principles calculations based on density-functional theory to investigate the structure, electronic properties, surface states, and topological properties of A15-type Mo₃Si compounds. The thermodynamic properties show that Mo₃Si exhibits thermodynamic stability, and its band structure and density of states indicate that Mo₃Si is a metallic compound. Meanwhile, the next calculations show the existence of potential topological properties of Mo₃Si, with suspected Dirac cones and many multiple concatenation points with linear dispersions in the vicinity of the Fermi energy level. In addition, the study of edge states suggests that topological surface states are highly likely to exist in Mo₃Si, revealing its potential applications in electron transport and quantum information processing. Its unique structural properties suggest that Mo₃Si is highly likely to be a topological material with broad potential applications.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143373259","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":"Spin Crossover of Local Copper-Oxygen States in the HTSC Cuprate La(_{2-x})Sr(_x)CuO(_4) Under the c-Axis Pressure","authors":"Ilya Makarov,&nbsp;Sergei Ovchinnikov","doi":"10.1007/s10948-025-06928-5","DOIUrl":"10.1007/s10948-025-06928-5","url":null,"abstract":"<div><p>In this work, the change in the energy and structure of local many-particle states of HTSC cuprate La<span>(_{2-x})</span>Sr<span>(_x)</span>CuO<span>(_4)</span> under the uniaxial compression along the <i>c</i>-axis is studied. Local copper-oxygen states are obtained using exact diagonalization of the CuO<span>(_6)</span> octahedron as a part of the GTB method for the five-band p-d model. The dependence of interatomic distances on the <i>c</i>-axis compression is calculated according to Hooke’s law using elastic constants; the influence of interatomic distances on the on-site energies and hopping integrals is obtained using linear extrapolation of the results of ab initio calculations and the theory of MT-orbitals, respectively. The <i>c</i>-axis compression leads to a decrease in the energy of hole states with the nature of the <span>(a_{1g})</span> symmetry orbitals. At a pressure value of <span>(P_{c1}^{left( c right) } = 11.8)</span> GPa, a spin crossover between the Zhang-Rice singlet and the triplet state <span>(B_1)</span> occurs. At higher pressures, a second spin crossover between two-hole states and a crossover of single-hole states with different orbital compositions were also detected. Taking into account the competition of various local states with changing the value of uniaxial compression, the effective five-band Hubbard model is formulated to describe the electronic structure of quasiparticle excitations.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361854","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":"Observation of Giant Zero-Field Cooled Spontaneous Exchange Bias Effect in La2FeCoO6 Double Perovskite Ceramic","authors":"Lav Kush,&nbsp;Sanjay Srivastava","doi":"10.1007/s10948-025-06927-6","DOIUrl":"10.1007/s10948-025-06927-6","url":null,"abstract":"<div><p>The La₂FeCoO₆ ceramic was synthesized via the sol–gel route, and their temperature-dependent exchange bias (EB) effects have been analyzed at different magnetic fields. XRD investigation reveals that at a lower temperature, the monoclinic structure with the P2₁/n space group was maintained, whereas, from room temperature to 450 K, the rhombohedral structure with the R3c space group was noticed. The tolerance factor suggested the presence of distortion, and the XPS analysis of Fe and Co confirms the defect sites in La₂FeCoO₆. Hence, the variety of magnetic phases formed during the FC and ZFC processes resulted in unidirectional anisotropy. Negative field cooling magnetization was observed in M-T measurements, and ferromagnetic clusters were detected at room temperature M-H measurements. Negative EB fields and upward shifts in hysteresis were observed at low temperatures. The hysteresis and EB fields changed below the Neel transition, with a transition from positive to negative EB observed with increasing magnetic field and temperature. The observed EB was attributed to the pinning effect of surface spins in interfacial frozen glassy states at the interface of large ferrimagnetic grains.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361648","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 Gradient Powering Spin Current in Quantum Dot-Magnetic Insulators Hybrid","authors":"Emil Siuda,&nbsp;Piotr Trocha","doi":"10.1007/s10948-025-06921-y","DOIUrl":"10.1007/s10948-025-06921-y","url":null,"abstract":"<div><p>The growing energy consumption of the computational sector worldwide necessitates the search for sustainable methods of powering and performing calculations. The fast-emerging field of spin caloritronics offers a promising solution by combining the advantages of performing computations on spins instead of charges and driving these computations through temperature differences rather than voltage. Among the various approaches, spin waves and their quanta of excitations, known as magnons, are considered promising carriers of spin-encoded information. In this article, we examine the magnon current generated in a system composed of a magnetic insulator/quantum dot/magnetic insulator, driven by a small temperature difference applied between the two insulators. By expanding the magnon current in terms of the applied temperature bias, we analyze the contributions of successive terms up to the third order of the temperature difference. Each term exhibits a similar structure, consisting of a driving-like and a damping-like component. The driving-like term is dependent on the coupling strength between the quantum dot and the electrodes. We explicitly show that the second-order term of the magnon current vanishes when the couplings of the quantum dot to the magnetic insulators are equal. Overall, the first two terms are sufficient to capture the behavior of the magnon current across the full range of temperature differences. For extreme values of the temperature gradient, the approximate results align with the exact ones only when there is significant asymmetry in the coupling strengths. Finally, we demonstrate that the system can function as a spin diode, capable of rectifying the magnon current when the temperature bias is reversed.</p></div>","PeriodicalId":669,"journal":{"name":"Journal of Superconductivity and Novel Magnetism","volume":"38 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143362058","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}