Journal of Magnetism and Magnetic Materials最新文献

英文中文

Concentration extraction and spatial distribution identification of heavy rare earth in EPMA images of sintered Nd–Fe–B

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-14 DOI: 10.1016/j.jmmm.2025.173028

Qichao Liang , Qiang Ma , Hao Wu , Rongshun Lai , Qianji Wang , Zhibin Li , Haibo Xu , Yangyang Zhang , Tao Qi

The addition of heavy rare earth elements to sintered Nd–Fe–B magnets through grain boundary diffusion techniques can significantly improve the coercivity of magnets with minimal reduction in remanence. The diffusion depth and distribution of the diffusion source are critical metrics for evaluating the efficiency of the diffusion process. Glow discharge mass spectrometry can sequentially strip layers of the magnet within a limited region to measure the concentration of the diffusion source at various depths. However, the accuracy is compromised by the multiphase nature of the base magnet material and the inhomogeneous distribution of the diffusion source. In contrast, electron probe microanalysis enables direct observation of the diffusion depth and distribution by analyzing diffusion cross-sections of the magnet. Coupled with digital image processing techniques, electron probe microanalysis allows high-throughput analysis of images to calculate concentration across depth intervals, establish depth-concentration relationships, and predict the concentration of heavy rare-earth elements at specific depths. Describing the distribution of diffusion sources presents a significant challenge. In this work, a probabilistic denoising diffusion model is proposed for the first time to quantify the distribution of the diffusion source. EPMA images were segmented into 3,700 distinct positions for model training. The trained model can generate diffusion images with the same distribution of heavy rare-earth elements at any position. By training on microscopic images of various magnets, the model establishes a profound correlation between magnet performance and microstructure, providing practical guidance for optimizing magnets or diffusion sources.

{"title":"Concentration extraction and spatial distribution identification of heavy rare earth in EPMA images of sintered Nd–Fe–B","authors":"Qichao Liang , Qiang Ma , Hao Wu , Rongshun Lai , Qianji Wang , Zhibin Li , Haibo Xu , Yangyang Zhang , Tao Qi","doi":"10.1016/j.jmmm.2025.173028","DOIUrl":"10.1016/j.jmmm.2025.173028","url":null,"abstract":"<div><div>The addition of heavy rare earth elements to sintered Nd–Fe–B magnets through grain boundary diffusion techniques can significantly improve the coercivity of magnets with minimal reduction in remanence. The diffusion depth and distribution of the diffusion source are critical metrics for evaluating the efficiency of the diffusion process. Glow discharge mass spectrometry can sequentially strip layers of the magnet within a limited region to measure the concentration of the diffusion source at various depths. However, the accuracy is compromised by the multiphase nature of the base magnet material and the inhomogeneous distribution of the diffusion source. In contrast, electron probe microanalysis enables direct observation of the diffusion depth and distribution by analyzing diffusion cross-sections of the magnet. Coupled with digital image processing techniques, electron probe microanalysis allows high-throughput analysis of images to calculate concentration across depth intervals, establish depth-concentration relationships, and predict the concentration of heavy rare-earth elements at specific depths. Describing the distribution of diffusion sources presents a significant challenge. In this work, a probabilistic denoising diffusion model is proposed for the first time to quantify the distribution of the diffusion source. EPMA images were segmented into 3,700 distinct positions for model training. The trained model can generate diffusion images with the same distribution of heavy rare-earth elements at any position. By training on microscopic images of various magnets, the model establishes a profound correlation between magnet performance and microstructure, providing practical guidance for optimizing magnets or diffusion sources.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173028"},"PeriodicalIF":2.5,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Tailoring the electronic and magnetic properties of AA-stacked ZnO bilayer by engineering covalently bonded F/N-intercalation or introducing SiC substrate 通过共价键F/N共掺或引入碳化硅衬底来定制AA叠层氧化锌双电层的电子和磁性能

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-13 DOI: 10.1016/j.jmmm.2025.173070

Lanli Chen , Hongduo Hu , Aiping Wang , Zhihua Xiong , Yuanyuan Cui , Yanfeng Gao

To meet the current requirements for diluted magnetic semiconductors, it is essential to design the materials with high stability and spin polarization for promoting the development of spintronic devices. Amelioration on the properties of two-dimensional ZnO bilayers for high-performance optoelectronic and spintronic remains a significant challenge and is highly anticipated. Herein, we systematically investigated the electronic structures and magnetic properties of AA-stacked ZnO bilayers through the first-principles calculations, focusing on the effects of covalently bonded F/N-intercalation and the introduction of SiC substrate. The results indicate that pristine ZnO BL, F@ZnO, N@ZnO bilayer and ZnO/SiC heterostructure exhibit dynamical, and mechanical and thermal stability. F@ZnO and N@ZnO exhibit magnetic properties, and the magnetic moments are 0.659 μ_B and 1.0 μ_B, which are primarily derived from O-2p and N-2p orbitals, respectively. F@ZnO exhibits half-metallic magnetic characteristics, whereas N@ZnO displays metallic features at high intercalation concentrations up to 100%. The stable half-metallicity originates from a spontaneous phase transition driven by Stoner instability due to the high density of states peak near the Fermi level. In ZnO/SiC heterostructure, one of the ZnO layers adjacent to the SiC layer becomes buckled with a height of 0.891 Å, while the other ZnO layer, situated farther from the SiC layer, remains planar. Furthermore, the system undergoes the transition from a nonmagnetic state to a ferromagnetic state due to the introduction of C atoms. These findings provide a new platform for designing 2D magnetic thin films, which could hold potential for enhancing the application of ZnO materials in optoelectronic and spintronic devices.

{"title":"Tailoring the electronic and magnetic properties of AA-stacked ZnO bilayer by engineering covalently bonded F/N-intercalation or introducing SiC substrate","authors":"Lanli Chen , Hongduo Hu , Aiping Wang , Zhihua Xiong , Yuanyuan Cui , Yanfeng Gao","doi":"10.1016/j.jmmm.2025.173070","DOIUrl":"10.1016/j.jmmm.2025.173070","url":null,"abstract":"<div><div>To meet the current requirements for diluted magnetic semiconductors, it is essential to design the materials with high stability and spin polarization for promoting the development of spintronic devices. Amelioration on the properties of two-dimensional ZnO bilayers for high-performance optoelectronic and spintronic remains a significant challenge and is highly anticipated. Herein, we systematically investigated the electronic structures and magnetic properties of AA-stacked ZnO bilayers through the first-principles calculations, focusing on the effects of covalently bonded F/N-intercalation and the introduction of SiC substrate. The results indicate that pristine ZnO BL, F@ZnO, N@ZnO bilayer and ZnO/SiC heterostructure exhibit dynamical, and mechanical and thermal stability. F@ZnO and N@ZnO exhibit magnetic properties, and the magnetic moments are 0.659 μ<sub>B</sub> and 1.0 μ<sub>B</sub>, which are primarily derived from O-2<em>p</em> and N-2<em>p</em> orbitals, respectively. F@ZnO exhibits half-metallic magnetic characteristics, whereas N@ZnO displays metallic features at high intercalation concentrations up to 100%. The stable half-metallicity originates from a spontaneous phase transition driven by Stoner instability due to the high density of states peak near the Fermi level. In ZnO/SiC heterostructure, one of the ZnO layers adjacent to the SiC layer becomes buckled with a height of 0.891 Å, while the other ZnO layer, situated farther from the SiC layer, remains planar. Furthermore, the system undergoes the transition from a nonmagnetic state to a ferromagnetic state due to the introduction of C atoms. These findings provide a new platform for designing 2D magnetic thin films, which could hold potential for enhancing the application of ZnO materials in optoelectronic and spintronic devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173070"},"PeriodicalIF":2.5,"publicationDate":"2025-04-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143829105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Preparation and characterization of PVDF/ CoFe2O4/g-C3N4 nanocomposite films for multi-functional applications

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-11 DOI: 10.1016/j.jmmm.2025.173029

R. Nirmal Kumar , J. Hemalatha

Polymer nanocomposite materials with different types of fillers play crucial role in various fields such as biomedical engineering, energy storage, power generation, robotics and automation, electromagnetic shielding, aerospace and defence, especially due to their excellent flexibility, ferroelectric, ferromagnetic, chemical sensing, piezoelectric, pyroelectric and rheological properties. The present study discusses fabrication of polymer nanocomposite films using polyvinylidene fluoride (PVDF) matrix with cobalt ferrite (CoFe₂O₄) and graphitic carbon nitride (g-C₃N₄) fillers and also their characterization. Crystalline CoFe₂O₄ nanoparticles and g-C₃N₄ were prepared and used to fabricate PVDF/CoFe₂O₄/g-C₃N₄ composite films. The structural and compositional details of crystalline CoFe₂O₄ nanoparticles and the composite films were analysed, along with the fraction of β-phase PVDF. The morphological, magnetic, and dielectric properties of the films were studied using field emission scanning electron microscopy, vibrating sample magnetometry, and LCR measurement respectively. XPS analysis of filler material shows the existence of moderate oxygen vacancy defects and oxygen lattice sites. It is observed the prepared composite film has high electroactive β phase with F(β) of 51 %, 42.4 % of oxygen vacancy defects, moderate saturation magnetization, high coercivity of 1469 Oe, significant magnetic hysteresis, dielectric constant of 26.5 and moderate dielectric loss, all these multi-functional properties reveal that the composite films are capable to shield Electromagnetic (EM) wave and useful for gas sensing applications.

{"title":"Preparation and characterization of PVDF/ CoFe2O4/g-C3N4 nanocomposite films for multi-functional applications","authors":"R. Nirmal Kumar , J. Hemalatha","doi":"10.1016/j.jmmm.2025.173029","DOIUrl":"10.1016/j.jmmm.2025.173029","url":null,"abstract":"<div><div>Polymer nanocomposite materials with different types of fillers play crucial role in various fields such as biomedical engineering, energy storage, power generation, robotics and automation, electromagnetic shielding, aerospace and defence, especially due to their excellent flexibility, ferroelectric, ferromagnetic, chemical sensing, piezoelectric, pyroelectric and rheological properties. The present study discusses fabrication of polymer nanocomposite films using polyvinylidene fluoride (PVDF) matrix with cobalt ferrite (CoFe<sub>2</sub>O<sub>4</sub>) and graphitic carbon nitride (g-C<sub>3</sub>N<sub>4</sub>) fillers and also their characterization. Crystalline CoFe<sub>2</sub>O<sub>4</sub> nanoparticles and g-C<sub>3</sub>N<sub>4</sub> were prepared and used to fabricate PVDF/CoFe<sub>2</sub>O<sub>4</sub>/g-C<sub>3</sub>N<sub>4</sub> composite films. The structural and compositional details of crystalline CoFe<sub>2</sub>O<sub>4</sub> nanoparticles and the composite films were analysed, along with the fraction of β-phase PVDF. The morphological, magnetic, and dielectric properties of the films were studied using field emission scanning electron microscopy, vibrating sample magnetometry, and LCR measurement respectively. XPS analysis of filler material shows the existence of moderate oxygen vacancy defects and oxygen lattice sites. It is observed the prepared composite film has high electroactive β phase with F(β) of 51 %, 42.4 % of oxygen vacancy defects, moderate saturation magnetization, high coercivity of 1469 Oe, significant magnetic hysteresis, dielectric constant of 26.5 and moderate dielectric loss, all these multi-functional properties reveal that the composite films are capable to shield Electromagnetic (EM) wave and useful for gas sensing applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173029"},"PeriodicalIF":2.5,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143835378","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The impact of magnesium oxide substituted strontium hexaferrite powder: Investigation on crystal structure and magnetic properties 氧化镁替代六价铁锶粉末的影响：晶体结构和磁性能研究

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-11 DOI: 10.1016/j.jmmm.2025.173060

Della Agustiana , Ramlan , Umer Daraz , Peisheng Lyu

The demand for magnets in both electrical and non-electrical equipment has seen a significant rise due to their diverse applications. Strontium Hexaferrite (SrFe₁₂O₁₉) hard magnet stand out for their excellent properties, including high Magnetic Saturation (M_s), Coercivity (H_c), Curie Temperature, and Chemical Stability. To further improve the properties of (SrFe₁₂O₁₉), doping with specific elements is necessary. In this article, (SrFe₁₂O₁₉) magnetic powder was prepared with MgO (0 %, 0.5 %, 1 %, 1.5 %, 2 % wt) addition using the powder metallurgy method. The characteristics of materials were studied through TG-DTA (Thermo-gravimetric – Differential Thermal Analysis), XRD (X-ray Diffraction), and VSM (Vibration Sample Magnetometer). DTA detects that the formation of SrFe₁₂O₁₉ occurs above 1000 °C with a mass reduction of only 0.344096 %. Thus, the sample calcination is conducted at 1100 °C. The addition of MgO led to a decrease in crystallite size, with the smallest crystallite size (36.78 nm by the Scherrer method and 38.40 nm analyzed by XRD) observed at 2 % MgO. Furthermore, MgO doping significantly increased the magnetic coercivity, reaching a maximum value of 3.437 kOe. This enhancement in coercivity is attributed to an increase in crystal anisotropy fields caused by Mg substitution, demonstrating the instrinsic effect of Mg on improving the coercive field.

{"title":"The impact of magnesium oxide substituted strontium hexaferrite powder: Investigation on crystal structure and magnetic properties","authors":"Della Agustiana , Ramlan , Umer Daraz , Peisheng Lyu","doi":"10.1016/j.jmmm.2025.173060","DOIUrl":"10.1016/j.jmmm.2025.173060","url":null,"abstract":"<div><div>The demand for magnets in both electrical and non-electrical equipment has seen a significant rise due to their diverse applications. Strontium Hexaferrite (SrFe<sub>12</sub>O<sub>19</sub>) hard magnet stand out for their excellent properties, including high Magnetic Saturation (M<sub>s</sub>), Coercivity (H<sub>c</sub>), Curie Temperature, and Chemical Stability. To further improve the properties of (SrFe<sub>12</sub>O<sub>19</sub>), doping with specific elements is necessary. In this article, (SrFe<sub>12</sub>O<sub>19</sub>) magnetic powder was prepared with MgO (0 %, 0.5 %, 1 %, 1.5 %, 2 % wt) addition using the powder metallurgy method. The characteristics of materials were studied through TG-DTA (Thermo-gravimetric – Differential Thermal Analysis), XRD (X-ray Diffraction), and VSM (Vibration Sample Magnetometer). DTA detects that the formation of SrFe<sub>12</sub>O<sub>19</sub> occurs above 1000 °C with a mass reduction of only 0.344096 %. Thus, the sample calcination is conducted at 1100 °C. The addition of MgO led to a decrease in crystallite size, with the smallest crystallite size (36.78 nm by the Scherrer method and 38.40 nm analyzed by XRD) observed at 2 % MgO. Furthermore, MgO doping significantly increased the magnetic coercivity, reaching a maximum value of 3.437 kOe. This enhancement in coercivity is attributed to an increase in crystal anisotropy fields caused by Mg substitution, demonstrating the instrinsic effect of Mg on improving the coercive field.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173060"},"PeriodicalIF":2.5,"publicationDate":"2025-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143825865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Effect of crystallization annealing on the formation of double-layer iron garnet films deposited by magnetron sputtering for photonics and integrated optics

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-10 DOI: 10.1016/j.jmmm.2025.173043

Tatiana V. Mikhailova , Sergey D. Lyashko , Sebastian V. Osmanov , Andrey V. Zolotaryov , Evgeny Yu. Semuk , Igor A. Naukhatsky , Alexander L. Kudryashov , Alexander N. Shaposhnikov , Vladimir N. Berzhansky , Yury E. Vysokikh , Sergey Yu. Krasnoborodko , Sergey S. Itskov

Two-step methods for the synthesis of magneto-optical iron garnets with a high bismuth content, based on the growth of a nonthermodynamical garnet with a high bismuth content on a thermodynamic garnet sublayer, have become widely known now. This paper shows how the degree of crystallinity of the garnet sublayer (yttrium iron garnet) affects the formation of the main magneto-optical layer (bismuth-substituted iron garnet). The degree of crystallinity of the sublayer was controlled by changing the time of crystallization annealing of the amorphous layer deposited by the magnetron method. Crystallization of the sublayer occurs through the formation of crystallization centers in the form of circular micron-sized islands. It has been experimentally demonstrated that a high-quality double-layer film with a large specific Faraday rotation of the main magneto-optical layer –27.78°/μm and a homogeneous polycrystalline structure is formed with an annealing duration of the sublayer of 60 min. The synthesized double-layer films in this case demonstrate record low coercivity for those obtained by vacuum sputtering methods, from 67 to 97 Oe. Double-layer films can be effectively used in photonic structures and nanodevices.

{"title":"Effect of crystallization annealing on the formation of double-layer iron garnet films deposited by magnetron sputtering for photonics and integrated optics","authors":"Tatiana V. Mikhailova , Sergey D. Lyashko , Sebastian V. Osmanov , Andrey V. Zolotaryov , Evgeny Yu. Semuk , Igor A. Naukhatsky , Alexander L. Kudryashov , Alexander N. Shaposhnikov , Vladimir N. Berzhansky , Yury E. Vysokikh , Sergey Yu. Krasnoborodko , Sergey S. Itskov","doi":"10.1016/j.jmmm.2025.173043","DOIUrl":"10.1016/j.jmmm.2025.173043","url":null,"abstract":"<div><div>Two-step methods for the synthesis of magneto-optical iron garnets with a high bismuth content, based on the growth of a nonthermodynamical garnet with a high bismuth content on a thermodynamic garnet sublayer, have become widely known now. This paper shows how the degree of crystallinity of the garnet sublayer (yttrium iron garnet) affects the formation of the main magneto-optical layer (bismuth-substituted iron garnet). The degree of crystallinity of the sublayer was controlled by changing the time of crystallization annealing of the amorphous layer deposited by the magnetron method. Crystallization of the sublayer occurs through the formation of crystallization centers in the form of circular micron-sized islands. It has been experimentally demonstrated that a high-quality double-layer film with a large specific Faraday rotation of the main magneto-optical layer –27.78°/μm and a homogeneous polycrystalline structure is formed with an annealing duration of the sublayer of 60 min. The synthesized double-layer films in this case demonstrate record low coercivity for those obtained by vacuum sputtering methods, from 67 to 97 Oe. Double-layer films can be effectively used in photonic structures and nanodevices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173043"},"PeriodicalIF":2.5,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143820431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Exchange interactions in Ba3Co2Fe24O41 ferrite

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-10 DOI: 10.1016/j.jmmm.2025.173046

Yanlin Ma , Yong yong Cao , Jie Li , Yida Lei , Yang Xiao , Yingli Liu , Zhiyong Zhong

Super exchange interactions are pivotal to understanding the magnetism of complex ferrites. In this study, the electronic structure, magnetism, and superexchange interactions of Co₂Z (Ba₃Co₂Fe₂₄O₄₁) were calculated using density functional theory (DFT) with the GGA + U method. The results indicate that Co₂Z exhibits semiconductor properties, with Fe³⁺ ions in all sublattices in a high-spin state. The band structure reveals strong hybridization between Fe 3d and O 2p orbitals, which forms the basis for the Fe-O-Fe super exchange interactions. Importantly, the exchange mechanism between all sublattices is antiferromagnetic, though the strength of the exchange interactions varies due to spatial differences among the sublattices, there is a strong exchange interaction between the sites 2a and 4f2*, 2d and 4f1. Moreover, the Curie temperature calculated (545 K) from the exchange integrals is close to the experimental value (600 K).

引用次数: 0

Magnetization jumps in proximity of an itinerant ferromagnet

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-10 DOI: 10.1016/j.jmmm.2025.172994

Carmine Autieri

Placing our system in the proximity of the Stoner instability, the mean-field theory of itinerant metamagnetism and its implications are discussed in this study for several different cases. Two analytically solvable models, namely the M

^{6}

Landau theory and the comprehensive analytical solution derived from the one-dimensional tight-binding density of state with the van Hove singularity (VHS), are presented. In our exploration, we calculate the analytical thermodynamic functionals, construct the phase diagrams, pinpoint the quantum critical endpoints, and delineate the critical magnetic fields. We examine the necessary and sufficient conditions for itinerant metamagnetism, scrutinizing the band structure effects and energy functionals. Finally, we extend the theoretical framework to the metamagnetic compound Sr

_{3}

_{2}

_{7}

by using an ab initio tight-binding. Our analysis reveals that the VHS plays a pivotal role in inducing metamagnetism in layered ruthenates Sr

_{3}

_{2}

_{7}

. Furthermore, we conduct a comparative analysis, discussing the distinctions between proximity to a ferromagnetic or an altermagnetic phase.

{"title":"Magnetization jumps in proximity of an itinerant ferromagnet","authors":"Carmine Autieri","doi":"10.1016/j.jmmm.2025.172994","DOIUrl":"10.1016/j.jmmm.2025.172994","url":null,"abstract":"<div><div>Placing our system in the proximity of the Stoner instability, the mean-field theory of itinerant metamagnetism and its implications are discussed in this study for several different cases. Two analytically solvable models, namely the M<span><math><msup><mrow></mrow><mrow><mn>6</mn></mrow></msup></math></span> Landau theory and the comprehensive analytical solution derived from the one-dimensional tight-binding density of state with the van Hove singularity (VHS), are presented. In our exploration, we calculate the analytical thermodynamic functionals, construct the phase diagrams, pinpoint the quantum critical endpoints, and delineate the critical magnetic fields. We examine the necessary and sufficient conditions for itinerant metamagnetism, scrutinizing the band structure effects and energy functionals. Finally, we extend the theoretical framework to the metamagnetic compound Sr<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Ru<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>7</mn></mrow></msub></math></span> by using an ab initio tight-binding. Our analysis reveals that the VHS plays a pivotal role in inducing metamagnetism in layered ruthenates Sr<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>Ru<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>7</mn></mrow></msub></math></span>. Furthermore, we conduct a comparative analysis, discussing the distinctions between proximity to a ferromagnetic or an altermagnetic phase.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 172994"},"PeriodicalIF":2.5,"publicationDate":"2025-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143817637","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Probing Quantum Spin Liquids in the Kitaev model through spin current measurements

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-09 DOI: 10.1016/j.jmmm.2025.173024

L.V. Santos, A.R. Moura

The Kitaev model is classified among an unconventional category of two-dimensional spin models characterized by direction-dependent interactions that facilitate Quantum Spin Liquid (QSL) states. Although the Kitaev model has resulted in extensive theoretical predictions, direct observations of QSL phases necessitate intricate experimental procedures due to the lack of any magnetic order. In this study, we introduce the theoretical analysis of an innovative method to detect the QSL characteristics of magnetic models by examining the spin current injected into the Kitaev model from an adjacent normal metal. We provide a comprehensive development of the injected spin current, identifying distinctive features that delineate the spin transport by Majorana fermions. The findings are compared with typical ferromagnetic junctions, for which the spin carries are provided by magnons, and leveraging insights from spintronics and quantum magnetism, we propose a novel mechanism to verify the existence of QSL states.

引用次数: 0

Magnetic response of environmentally friendly prepared La3+ doped Li-Cu spinel ferrites

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-09 DOI: 10.1016/j.jmmm.2025.173056

A.U. Rahman , A. Alhadhrami , Mohamed M. Ibrahim , Gaber A.M. Mersal

In this study, the Li_0.1Cu_0.5Fe_2.3–yLa_yO₄ (y = 0.0, 0.1, 0.2, 0.3, 0.4) spinel ferrites (SFs) were synthesized via self-ignition route, and their structural, morphological, compositional and magnetic properties were systematically analyzed. X-ray diffraction (XRD) analysis revealed a slight shift in the (311) diffraction peak position with increasing La³⁺ concentration, indicating lattice distortion. The crystallite size (D) decreased from 29.1 nm to 17.3 nm with doping, while lattice constant (a) and unit cell volume (V) exhibited a decreasing trend, confirming structural modifications due to La³⁺ addition in Li-Cu spinel lattice. Moreover, the particle size was also decreased from 42 nm to 22 nm with the substitution of La³⁺. Magnetic response demonstrated a significant reduction in saturation magnetization (M_S), from 60 emu/g to 23 emu/g, and coercivity (H_C), from 1331 Oe to 639 Oe, suggesting weakened magnetic interactions. The squareness ratio (SQ) increased, while the magnetocrystalline anisotropy constant (K) decreased, indicating enhanced magnetic softness. Furthermore, the microwave operating frequency (ω_m) was also reduced with La³⁺ doping, highlighting changes in dynamic magnetic behavior. These findings suggest that La³⁺ doping effectively tailors the structural and magnetic properties of Li-Cu SFs, making them potential candidates for tunable magnetic applications including recording media, memory devices, and transformer core applications.

{"title":"Magnetic response of environmentally friendly prepared La3+ doped Li-Cu spinel ferrites","authors":"A.U. Rahman , A. Alhadhrami , Mohamed M. Ibrahim , Gaber A.M. Mersal","doi":"10.1016/j.jmmm.2025.173056","DOIUrl":"10.1016/j.jmmm.2025.173056","url":null,"abstract":"<div><div>In this study, the Li<sub>0.1</sub>Cu<sub>0.5</sub>Fe<sub>2.3–y</sub>La<sub>y</sub>O<sub>4</sub> (y = 0.0, 0.1, 0.2, 0.3, 0.4) spinel ferrites (SFs) were synthesized <em>via</em> self-ignition route, and their structural, morphological, compositional and magnetic properties were systematically analyzed. X-ray diffraction (XRD) analysis revealed a slight shift in the (311) diffraction peak position with increasing La<sup>3+</sup> concentration, indicating lattice distortion. The crystallite size (D) decreased from 29.1 nm to 17.3 nm with doping, while lattice constant (a) and unit cell volume (V) exhibited a decreasing trend, confirming structural modifications due to La<sup>3+</sup> addition in Li-Cu spinel lattice. Moreover, the particle size was also decreased from 42 nm to 22 nm with the substitution of La<sup>3+</sup>. Magnetic response demonstrated a significant reduction in saturation magnetization (M<sub>S</sub>), from 60 emu/g to 23 emu/g, and coercivity (H<sub>C</sub>), from 1331 Oe to 639 Oe, suggesting weakened magnetic interactions. The squareness ratio (SQ) increased, while the magnetocrystalline anisotropy constant (K) decreased, indicating enhanced magnetic softness. Furthermore, the microwave operating frequency (ω<sub>m</sub>) was also reduced with La<sup>3+</sup> doping, highlighting changes in dynamic magnetic behavior. These findings suggest that La<sup>3+</sup> doping effectively tailors the structural and magnetic properties of Li-Cu SFs, making them potential candidates for tunable magnetic applications including recording media, memory devices, and transformer core applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173056"},"PeriodicalIF":2.5,"publicationDate":"2025-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143824499","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

The structural, electronic, magnetic and optical properties of the binary Heusler alloy CaF3

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-04-08 DOI: 10.1016/j.jmmm.2025.173048

Ting Song, Shuai-Jun Liu, Shuang-Gang Xu, Hao Wu, Jun-Hong Tian, Xiao-Wei Sun

The structural, electronic, magnetic and optical properties of the binary Heusler alloy CaF₃ have been investigated using a first-principles approach based on density functional theory. The predicted structure of CaF₃ and the structure of the Heusler alloy at pressures from 0 to 100 GPa are investigated, and it is found that the

Pm \bar{3} n

structure has the lowest energy and its most stable state is the ferromagnetic state in the whole range of pressures investigated, and verified to satisfy the stability thermodynamically, mechanically, and dynamical. Subsequently, the bandgap, the magnetic moment, and the spin polarisability of the

Pm \bar{3} n

structure near the Fermi energy level at 0 GPa, show semi-metallic properties and can be maintained up to 10 GPa. Finally, the reflectance, refractive index, and absorption coefficient are used to explain the optical properties of the

Pm \bar{3} n

structure, and it is found that the reflectance is almost close to 100% in the visible region, which implies that it can be used as a reflective material in the visible light range. The characterization study of binary Heusler alloy CaF₃ research study helps in the design and optimization of spintronic devices and optoelectronic devices.

{"title":"The structural, electronic, magnetic and optical properties of the binary Heusler alloy CaF3","authors":"Ting Song, Shuai-Jun Liu, Shuang-Gang Xu, Hao Wu, Jun-Hong Tian, Xiao-Wei Sun","doi":"10.1016/j.jmmm.2025.173048","DOIUrl":"10.1016/j.jmmm.2025.173048","url":null,"abstract":"<div><div>The structural, electronic, magnetic and optical properties of the binary Heusler alloy CaF<sub>3</sub> have been investigated using a first-principles approach based on density functional theory. The predicted structure of CaF<sub>3</sub> and the structure of the Heusler alloy at pressures from 0 to 100 GPa are investigated, and it is found that the <span><math><mrow><mi>Pm</mi><mover><mrow><mn>3</mn></mrow><mrow><mo>¯</mo></mrow></mover><mi>n</mi></mrow></math></span> structure has the lowest energy and its most stable state is the ferromagnetic state in the whole range of pressures investigated, and verified to satisfy the stability thermodynamically, mechanically, and dynamical. Subsequently, the bandgap, the magnetic moment, and the spin polarisability of the <span><math><mrow><mi>Pm</mi><mover><mrow><mn>3</mn></mrow><mrow><mo>¯</mo></mrow></mover><mi>n</mi></mrow></math></span> structure near the Fermi energy level at 0 GPa, show semi-metallic properties and can be maintained up to 10 GPa. Finally, the reflectance, refractive index, and absorption coefficient are used to explain the optical properties of the <span><math><mrow><mi>Pm</mi><mover><mrow><mn>3</mn></mrow><mrow><mo>¯</mo></mrow></mover><mi>n</mi></mrow></math></span> structure, and it is found that the reflectance is almost close to 100% in the visible region, which implies that it can be used as a reflective material in the visible light range. The characterization study of binary Heusler alloy CaF<sub>3</sub> research study helps in the design and optimization of spintronic devices and optoelectronic devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"624 ","pages":"Article 173048"},"PeriodicalIF":2.5,"publicationDate":"2025-04-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143825782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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