<div><div>In this study, we examine the magnetic properties and critical behavior of <span><math><mrow><mi>L</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>4</mn></mrow></msub><mi>C</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>4</mn></mrow></msub><mi>M</mi><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mi>C</mi><msub><mrow><mi>r</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span>(LCMCO). The magnetic analysis indicates strong ferromagnetic ordering at low temperatures, transitioning to a paramagnetic state around 280 K. Three prominent transition peaks are observed: the first at T<sub>1</sub> = 40.2 K, corresponding to spin reorientation between Mn<span><math><msup><mrow></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math></span>/Mn<span><math><msup><mrow></mrow><mrow><mn>4</mn><mo>+</mo></mrow></msup></math></span> and Mn<span><math><msup><mrow></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math></span>/Mn<span><math><msup><mrow></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup></math></span> via double and super exchange interactions; the second at T<sub>2</sub> = 208.3 K, leads to the competition between antiferromagnetic and ferromagnetic correlations caused by spin clusters; and the third at T<sub>3</sub> = 279.6 K, marking the transition to a paramagnetic state, as revealed by <span><math><mfrac><mrow><mi>d</mi><mi>χ</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow><mrow><mi>d</mi><mi>T</mi></mrow></mfrac></math></span>. The critical behavior analysis determined the exponents <span><math><mi>β</mi></math></span>, <span><math><mi>γ</mi></math></span>, and <span><math><mi>δ</mi></math></span> to be 0.17, 0.76, and 1.32, respectively. These values deviate from standard critical exponents model, indicating the absence of a conventional second-order phase transition. This behavior arises from the competing magnetic spin interactions between the distinct chemical states of <span><math><mrow><mi>M</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn><mo>+</mo><mo>/</mo><mn>3</mn><mo>+</mo><mo>/</mo><mn>4</mn><mo>+</mo></mrow></msup></mrow></math></span> and <span><math><mrow><mi>C</mi><msup><mrow><mi>r</mi></mrow><mrow><mn>3</mn><mo>+</mo><mo>/</mo><mn>6</mn><mo>+</mo></mrow></msup></mrow></math></span> due to the formation of oxygen vacancies resulting from hole doping. This leads to the magnetic spin clusters that prevent the establishment of a fully ferromagnetic interaction. The oxygen defects (<span><math><mi>μ</mi></math></span>) is approximately 1.7%, influencing the average valency of O, Mn, and Cr, which play a significant role in modifying the magnetic interactions. The impact of oxygen vacancies on the magnetic properties are investigated computationally by constructing a <span><math><mrow><mn>2</mn><mo>×</mo><mn>2</mn><mo>×</mo><mn>2</mn></mrow></math></span> supercell of LCMCO a
{"title":"Inconsistency in the critical behavior and magnetic phase transition of La3/4Ca1/4Mn1/2Cr1/2O3","authors":"Aditya Kumar Kushwaha, Hodam Karnajit Singh, Pamu Dobbidi","doi":"10.1016/j.jmmm.2025.172948","DOIUrl":"10.1016/j.jmmm.2025.172948","url":null,"abstract":"<div><div>In this study, we examine the magnetic properties and critical behavior of <span><math><mrow><mi>L</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>4</mn></mrow></msub><mi>C</mi><msub><mrow><mi>a</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>4</mn></mrow></msub><mi>M</mi><msub><mrow><mi>n</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><mi>C</mi><msub><mrow><mi>r</mi></mrow><mrow><mn>1</mn><mo>/</mo><mn>2</mn></mrow></msub><msub><mrow><mi>O</mi></mrow><mrow><mn>3</mn></mrow></msub></mrow></math></span>(LCMCO). The magnetic analysis indicates strong ferromagnetic ordering at low temperatures, transitioning to a paramagnetic state around 280 K. Three prominent transition peaks are observed: the first at T<sub>1</sub> = 40.2 K, corresponding to spin reorientation between Mn<span><math><msup><mrow></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math></span>/Mn<span><math><msup><mrow></mrow><mrow><mn>4</mn><mo>+</mo></mrow></msup></math></span> and Mn<span><math><msup><mrow></mrow><mrow><mn>3</mn><mo>+</mo></mrow></msup></math></span>/Mn<span><math><msup><mrow></mrow><mrow><mn>2</mn><mo>+</mo></mrow></msup></math></span> via double and super exchange interactions; the second at T<sub>2</sub> = 208.3 K, leads to the competition between antiferromagnetic and ferromagnetic correlations caused by spin clusters; and the third at T<sub>3</sub> = 279.6 K, marking the transition to a paramagnetic state, as revealed by <span><math><mfrac><mrow><mi>d</mi><mi>χ</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow></mrow><mrow><mi>d</mi><mi>T</mi></mrow></mfrac></math></span>. The critical behavior analysis determined the exponents <span><math><mi>β</mi></math></span>, <span><math><mi>γ</mi></math></span>, and <span><math><mi>δ</mi></math></span> to be 0.17, 0.76, and 1.32, respectively. These values deviate from standard critical exponents model, indicating the absence of a conventional second-order phase transition. This behavior arises from the competing magnetic spin interactions between the distinct chemical states of <span><math><mrow><mi>M</mi><msup><mrow><mi>n</mi></mrow><mrow><mn>2</mn><mo>+</mo><mo>/</mo><mn>3</mn><mo>+</mo><mo>/</mo><mn>4</mn><mo>+</mo></mrow></msup></mrow></math></span> and <span><math><mrow><mi>C</mi><msup><mrow><mi>r</mi></mrow><mrow><mn>3</mn><mo>+</mo><mo>/</mo><mn>6</mn><mo>+</mo></mrow></msup></mrow></math></span> due to the formation of oxygen vacancies resulting from hole doping. This leads to the magnetic spin clusters that prevent the establishment of a fully ferromagnetic interaction. The oxygen defects (<span><math><mi>μ</mi></math></span>) is approximately 1.7%, influencing the average valency of O, Mn, and Cr, which play a significant role in modifying the magnetic interactions. The impact of oxygen vacancies on the magnetic properties are investigated computationally by constructing a <span><math><mrow><mn>2</mn><mo>×</mo><mn>2</mn><mo>×</mo><mn>2</mn></mrow></math></span> supercell of LCMCO a","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172948"},"PeriodicalIF":2.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643577","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}
Pub Date : 2025-03-15DOI: 10.1016/j.jmmm.2025.172962
Z. Fadil , Chaitany Jayprakash Raorane , Steve Karam , A. Samih , Seong Cheol Kim , E. Salmani , Abdulrahman A. Alsayyari , Khaled H. Mahmoud
This study used Monte Carlo simulations to delve into the magnetic features of fullerene C60 and graphene nanostructures. Fullerene exhibits a higher blocking temperature (TB) under an external magnetic field (H), indicating increased sensitivity to magnetic ordering at higher temperatures. In contrast, graphene demonstrates a distinct behavioral reversal when H was absent. Both nanostructures exhibit progressive transitions from ferromagnetic to superparamagnetic behavior, with delayed shifts influenced by linear (J) and biquadratic (K) coupling. Fullerene’s flexibility suggests applications in adjustable magnetic systems, while graphene’s stability makes it suitable for high-frequency uses and stable electronics.
本研究利用蒙特卡罗模拟深入研究了富勒烯 C60 和石墨烯纳米结构的磁性特征。富勒烯在外部磁场（H）作用下表现出较高的阻滞温度（TB），表明在较高温度下对磁有序的敏感性增加。相比之下，石墨烯在没有 H 的情况下表现出明显的行为逆转。这两种纳米结构都表现出从铁磁性到超顺磁性的渐进转变，延迟转变受到线性（J）和双四边形（K）耦合的影响。富勒烯的灵活性使其适用于可调磁性系统，而石墨烯的稳定性使其适用于高频应用和稳定的电子器件。
{"title":"Comparative study of magnetic properties in graphene and fullerene C60 nanostructures via Monte Carlo simulations","authors":"Z. Fadil , Chaitany Jayprakash Raorane , Steve Karam , A. Samih , Seong Cheol Kim , E. Salmani , Abdulrahman A. Alsayyari , Khaled H. Mahmoud","doi":"10.1016/j.jmmm.2025.172962","DOIUrl":"10.1016/j.jmmm.2025.172962","url":null,"abstract":"<div><div>This study used Monte Carlo simulations to delve into the magnetic features of fullerene <em>C</em><sub>60</sub> and graphene nanostructures. Fullerene exhibits a higher blocking temperature (T<sub>B</sub>) under an external magnetic field (H), indicating increased sensitivity to magnetic ordering at higher temperatures. In contrast, graphene demonstrates a distinct behavioral reversal when H was absent. Both nanostructures exhibit progressive transitions from ferromagnetic to superparamagnetic behavior, with delayed shifts influenced by linear (J) and biquadratic (K) coupling. Fullerene’s flexibility suggests applications in adjustable magnetic systems, while graphene’s stability makes it suitable for high-frequency uses and stable electronics.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172962"},"PeriodicalIF":2.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643574","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}
Pub Date : 2025-03-15DOI: 10.1016/j.jmmm.2025.172960
A.E. Vidal , J.W. Alegre , Y. Núñez , H.N. Vergara , J.I. Costilla , A. Talledo , B.R. Pujada
In this paper, we present a computational study predicting the phase-stability skyrmion maps, internal magnetic configuration, and radii of magnetic skyrmions in rectangular magnetic nanostructures, using machine learning (ML) algorithms. The rectangular magnetic nanostructures have a fixed length of 128 nm and variable widths ranging from 56 and 128 nm. The study considers different values of perpendicular magnetic anisotropy and the Dzyaloshinskii-Moriya interaction constants. Artificial neural networks (ANNs) and Generative Adversarial Networks (GANs) were successfully employed to predict phase-stability skyrmion maps, internal magnetization images, and magnetization profiles along the z-axes for circular magnetic skyrmions. These predictions were validated through simulations using the micromagnetic Mumax3 program, demonstrating the success of the machine learning approach despite the complexity of the magnetic interactions. The results of this work highlight the potential of machine learning algorithms in advancing the study of magnetic skyrmions in confined magnetic nanostructures by accurately predicting a wide range of scenarios in a significant short time.
{"title":"Computational prediction of phase-stability skyrmion maps, internal magnetic configuration, and size of magnetic skyrmions in confined magnetic nanostructures","authors":"A.E. Vidal , J.W. Alegre , Y. Núñez , H.N. Vergara , J.I. Costilla , A. Talledo , B.R. Pujada","doi":"10.1016/j.jmmm.2025.172960","DOIUrl":"10.1016/j.jmmm.2025.172960","url":null,"abstract":"<div><div>In this paper, we present a computational study predicting the phase-stability skyrmion maps, internal magnetic configuration, and radii of magnetic skyrmions in rectangular magnetic nanostructures, using machine learning (ML) algorithms. The rectangular magnetic nanostructures have a fixed length of 128 nm and variable widths ranging from 56 and 128 nm. The study considers different values of perpendicular magnetic anisotropy and the Dzyaloshinskii-Moriya interaction constants. Artificial neural networks (ANNs) and Generative Adversarial Networks (GANs) were successfully employed to predict phase-stability skyrmion maps, internal magnetization images, and magnetization profiles along the z-axes for circular magnetic skyrmions. These predictions were validated through simulations using the micromagnetic Mumax3 program, demonstrating the success of the machine learning approach despite the complexity of the magnetic interactions. The results of this work highlight the potential of machine learning algorithms in advancing the study of magnetic skyrmions in confined magnetic nanostructures by accurately predicting a wide range of scenarios in a significant short time.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172960"},"PeriodicalIF":2.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632161","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}
Pub Date : 2025-03-15DOI: 10.1016/j.jmmm.2025.172982
Sinan Zhang , Tong Gao , Xi Chu , Chuanfang Chen
Tumors pose a serious threat to human health and have long been the center of attention in the medical field. In addition to conventional tumor treatment modalities, nano-therapy for tumors has been particularly developed. The magneto-mechanical force in tumor treatment has gradually attracted people’s attention. The mechanical force generated by magnetic nanoparticles under the magnetic field can damage tumor cells. This method is precise and non-invasive. It can also be combined with other methods to boost the effectiveness of tumor treatment further. This work reviews the reports of the application of mechanical force generated by magnetic nanoparticles under the magnetic field in tumor treatment, and the prospects are prospected.
{"title":"Application of mechanical force generated by magnetic nanoparticles under magnetic field in tumor treatment","authors":"Sinan Zhang , Tong Gao , Xi Chu , Chuanfang Chen","doi":"10.1016/j.jmmm.2025.172982","DOIUrl":"10.1016/j.jmmm.2025.172982","url":null,"abstract":"<div><div>Tumors pose a serious threat to human health and have long been the center of attention in the medical field. In addition to conventional tumor treatment modalities, nano-therapy for tumors has been particularly developed. The magneto-mechanical force in tumor treatment has gradually attracted people’s attention. The mechanical force generated by magnetic nanoparticles under the magnetic field can damage tumor cells. This method is precise and non-invasive. It can also be combined with other methods to boost the effectiveness of tumor treatment further. This work reviews the reports of the application of mechanical force generated by magnetic nanoparticles under the magnetic field in tumor treatment, and the prospects are prospected.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172982"},"PeriodicalIF":2.5,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643578","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}
Pub Date : 2025-03-14DOI: 10.1016/j.jmmm.2025.172939
Eduardo Saavedra , Piero Terruzzi , Juan Luis Palma , Juan Escrig
Through numerical simulations, we investigate the equilibrium states and dynamic responses of stadium-shaped and elliptical nanodots in the absence of a bias field. Our findings reveal two distinct equilibrium states – single domain and vortex – identified in these nanodots. Notably, the resonant frequencies and the number of peaks in the dynamics response are shown to be influenced by the minimum energy configuration, which is intricately linked to the system’s aspect ratio. The insights gained from this exploration contribute to a deeper understanding of the interplay between geometric parameters and dynamic behavior in low-dimensional magnetic nanostructures, offering valuable considerations for the design and optimization of on-chip microwave devices in spintronics and magnonics applications.
{"title":"Interplay between geometry and spin dynamics in elongated magnetic nanoislands: Elliptical vs stadium-shaped cases","authors":"Eduardo Saavedra , Piero Terruzzi , Juan Luis Palma , Juan Escrig","doi":"10.1016/j.jmmm.2025.172939","DOIUrl":"10.1016/j.jmmm.2025.172939","url":null,"abstract":"<div><div>Through numerical simulations, we investigate the equilibrium states and dynamic responses of stadium-shaped and elliptical nanodots in the absence of a bias field. Our findings reveal two distinct equilibrium states – single domain and vortex – identified in these nanodots. Notably, the resonant frequencies and the number of peaks in the dynamics response are shown to be influenced by the minimum energy configuration, which is intricately linked to the system’s aspect ratio. The insights gained from this exploration contribute to a deeper understanding of the interplay between geometric parameters and dynamic behavior in low-dimensional magnetic nanostructures, offering valuable considerations for the design and optimization of on-chip microwave devices in spintronics and magnonics applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172939"},"PeriodicalIF":2.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632162","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}
Pub Date : 2025-03-14DOI: 10.1016/j.jmmm.2025.172938
S.M. Bakharev, M.A. Borich, S.P. Savchenko
The dependencies of the caustic patterns of magnetoelastic waves on the direction of the magnetic field in Fe82Ga18 crystals are investigated. The phenomenological approach is used. The long-wavelength approximation is assumed in this approach. The energy of the system is made up of three terms: elastic, magnetic, and magnetoelastic. The caustic patterns are calculated for the diagonal plane of the crystal.
{"title":"Magnetoelastic wave caustic pattern dependency on direction of magnetic field in Fe82Ga18 crystals","authors":"S.M. Bakharev, M.A. Borich, S.P. Savchenko","doi":"10.1016/j.jmmm.2025.172938","DOIUrl":"10.1016/j.jmmm.2025.172938","url":null,"abstract":"<div><div>The dependencies of the caustic patterns of magnetoelastic waves on the direction of the magnetic field in Fe<sub>82</sub>Ga<sub>18</sub> crystals are investigated. The phenomenological approach is used. The long-wavelength approximation is assumed in this approach. The energy of the system is made up of three terms: elastic, magnetic, and magnetoelastic. The caustic patterns are calculated for the diagonal plane of the crystal.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172938"},"PeriodicalIF":2.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643576","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}
Pub Date : 2025-03-14DOI: 10.1016/j.jmmm.2025.172969
Bo Meng, Ou Man Lin, Hongyun Zhang
In this work, we investigated the stability, electronic structures, and magnetic properties of a 2D pentagonal iron phosphide (penta-FeP2) through density functional theory (DFT) calculations. The predicted penta-FeP2 is an FM semiconductor with thermal, dynamical, and mechanical stability, and narrow direct band gap of 0.916 eV. The estimated TC surpasses 705 K, which is sufficiently higher than room temperature. The MAE is as high as 358 μeV/Fe, which enhances the FM stability of the penta-FeP2. In addition, the 2D material also exhibits ultrahigh mobility for both holes and electrons. The light electron mobility is up to 21, 992 cm2 V−1 s−1, while the light hole mobility is 2, 890 cm2 V−1 s−1. It also exhibits isotropic visible light absorption and a low lattice thermal conductivity of ∼20 W m−1 K−1 at room temperature. The 2D FeP2 displays a number of desirable properties, including excellent stability, high TC, large MAE, high carrier mobility, and a direct band gap. These characteristics make it a promising candidate for spintronic devices.
{"title":"Two-dimensional ferromagnetic penta-FeP2 with high Curie temperature and carrier mobility","authors":"Bo Meng, Ou Man Lin, Hongyun Zhang","doi":"10.1016/j.jmmm.2025.172969","DOIUrl":"10.1016/j.jmmm.2025.172969","url":null,"abstract":"<div><div>In this work, we investigated the stability, electronic structures, and magnetic properties of a 2D pentagonal iron phosphide (penta-FeP<sub>2</sub>) through density functional theory (DFT) calculations. The predicted penta-FeP<sub>2</sub> is an FM semiconductor with thermal, dynamical, and mechanical stability, and narrow direct band gap of 0.916 eV. The estimated T<sub>C</sub> surpasses 705 K, which is sufficiently higher than room temperature. The MAE is as high as 358 μeV/Fe, which enhances the FM stability of the penta-FeP<sub>2</sub>. In addition, the 2D material also exhibits ultrahigh mobility for both holes and electrons. The light electron mobility is up to 21, 992 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>, while the light hole mobility is 2, 890 cm<sup>2</sup> V<sup>−1</sup> s<sup>−1</sup>. It also exhibits isotropic visible light absorption and a low lattice thermal conductivity of ∼20 W m<sup>−1</sup> K<sup>−1</sup> at room temperature. The 2D FeP<sub>2</sub> displays a number of desirable properties, including excellent stability, high T<sub>C</sub>, large MAE, high carrier mobility, and a direct band gap. These characteristics make it a promising candidate for spintronic devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172969"},"PeriodicalIF":2.5,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143643575","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}
The monoisotopic impurity ions of 53Cr in a single crystal of yttrium orthosilicate (Y2SiO5) have been studied by the electron paramagnetic resonance (EPR). Several X-band EPR spin transitions of the chromium ion (S = 3/2) were recorded in magnetic fields up to 1.7 T. The chromium ion exhibited a substantial fine structure of spin sublevels, with two doublets split by 53 GHz. As a consequence of the high anisotropy of the zero-field interactions, the resonance conditions of the EPR transitions are strongly dependent on the direction of the external magnetic field relative to the crystallographic axes. In some orientations, the nonlinear dependence of the spin sublevels on the magnetic field leads to the formation of an anticrossing between spin states with projections and . In addition to this well established anticrossing region, a new region formed by the states with projections and has been identified. It appears near the upper limit of the EPR spectrometer (1.7 T), where the core of the spectrometer magnet approaches saturation. The EPR spectra of the scandium endofullerene Sc2@C80(CH2Ph) are taken as a standard to calibrate the magnetic field in this regime. This procedure enables a more accurate determination of the fine structure of the chromium ion. The values D = 25.07 GHz and E = 5.29 GHz are derived by comparing calibrated experimental data with numerical simulations.
{"title":"A new anticrossing region of monoisotopic impurity 53Cr ions in Y2SiO5","authors":"R.B. Zaripov, I.T. Khairutdinov, V.F. Tarasov, Yu.E. Kandrashkin","doi":"10.1016/j.jmmm.2025.172956","DOIUrl":"10.1016/j.jmmm.2025.172956","url":null,"abstract":"<div><div>The monoisotopic impurity ions of <sup>53</sup>Cr in a single crystal of yttrium orthosilicate (Y<sub>2</sub>SiO<sub>5</sub>) have been studied by the electron paramagnetic resonance (EPR). Several X-band EPR spin transitions of the chromium ion (S = 3/2) were recorded in magnetic fields up to 1.7 T. The chromium ion exhibited a substantial fine structure of spin sublevels, with two doublets split by 53 GHz. As a consequence of the high anisotropy of the zero-field interactions, the resonance conditions of the EPR transitions are strongly dependent on the direction of the external magnetic field relative to the crystallographic axes. In some orientations, the nonlinear dependence of the spin sublevels on the magnetic field leads to the formation of an anticrossing between spin states with projections <span><math><mrow><msub><mi>m</mi><mi>S</mi></msub><mo>=</mo><mo>+</mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msub><mi>m</mi><mi>S</mi></msub><mo>=</mo><mo>-</mo><mn>3</mn><mo>/</mo><mn>2</mn></mrow></math></span>. In addition to this well established anticrossing region, a new region formed by the states with projections <span><math><mrow><msub><mi>m</mi><mi>S</mi></msub><mo>=</mo><mo>-</mo><mn>1</mn><mo>/</mo><mn>2</mn></mrow></math></span> and <span><math><mrow><msub><mi>m</mi><mi>S</mi></msub><mo>=</mo><mo>-</mo><mn>3</mn><mo>/</mo><mn>2</mn></mrow></math></span> has been identified. It appears near the upper limit of the EPR spectrometer (1.7 T), where the core of the spectrometer magnet approaches saturation. The EPR spectra of the scandium endofullerene Sc<sub>2</sub>@C<sub>80</sub>(CH<sub>2</sub>Ph) are taken as a standard to calibrate the magnetic field in this regime. This procedure enables a more accurate determination of the fine structure of the chromium ion. The values D = 25.07 GHz and E = 5.29 GHz are derived by comparing calibrated experimental data with numerical simulations.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172956"},"PeriodicalIF":2.5,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143627900","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}
La-Fe-Si alloys are of high interest for near room temperature magnetocaloric applications. La1.4Fe11Co0.8Si1.2 magnetocaloric composites were prepared by hot-deformation and diffusion annealing to improve the kinetics of the formation rate of the desired 1:13 phase and reduce its brittleness. The effects of La1.4Fe11Co0.8Si1.2 particle size on the formation of 1:13 phase, as well as the magnetocaloric, mechanical and corrosion properties were investigated. The results showed that the process deployed in this work shortened the annealing time and promoted the formation of 1:13 phase. The initial particle size influenced phase formation during diffusion annealing. For smaller particle size, the 1:13 phase content and microstructural homogeneity were enhanced after annealing. The diffusion distance between the La-rich phase and the α-Fe phase decreased. Significantly, the bulk composites exhibited a large magnetic entropy change (5.6–6.1 J·kg−1·K−1, μ0ΔH = 2 T) and high refrigeration cooling power (128.7–142.1 J·kg−1) near room temperature owing to its high 1:13 phase content. These composites also had large bending strength and good corrosion resistance. Thus, this processing technology was demonstrated to be a facile method to fabricate magnetocaloric composites with excellent near room temperature performance.
{"title":"Improvement in magnetocaloric, mechanical and corrosion properties of La1.4Fe11Co0.8Si1.2 bulk composites prepared by hot-deformation and diffusion annealing","authors":"X.C. Zhong , Z.H. Liao , G.P. Li , X. Huang , J.H. Huang , C.L. Liu , Y.D. Zhang , Z.W. Liu , D.L. Jiao , W.Q. Qiu , R.V. Ramanujan","doi":"10.1016/j.jmmm.2025.172944","DOIUrl":"10.1016/j.jmmm.2025.172944","url":null,"abstract":"<div><div>La-Fe-Si alloys are of high interest for near room temperature magnetocaloric applications. La<sub>1.4</sub>Fe<sub>11</sub>Co<sub>0.8</sub>Si<sub>1.2</sub> magnetocaloric composites were prepared by hot-deformation and diffusion annealing to improve the kinetics of the formation rate of the desired 1:13 phase and reduce its brittleness. The effects of La<sub>1.4</sub>Fe<sub>11</sub>Co<sub>0.8</sub>Si<sub>1.2</sub> particle size on the formation of 1:13 phase, as well as the magnetocaloric, mechanical and corrosion properties were investigated. The results showed that the process deployed in this work shortened the annealing time and promoted the formation of 1:13 phase. The initial particle size influenced phase formation during diffusion annealing. For smaller particle size, the 1:13 phase content and microstructural homogeneity were enhanced after annealing. The diffusion distance between the La-rich phase and the α-Fe phase decreased. Significantly, the bulk composites exhibited a large magnetic entropy change (5.6–6.1 J·kg<sup>−1</sup>·K<sup>−1</sup>, <em>μ</em><sub>0</sub>Δ<em>H</em> = 2 T) and high refrigeration cooling power (128.7–142.1 J·kg<sup>−1</sup>) near room temperature owing to its high 1:13 phase content. These composites also had large bending strength and good corrosion resistance. Thus, this processing technology was demonstrated to be a facile method to fabricate magnetocaloric composites with excellent near room temperature performance.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172944"},"PeriodicalIF":2.5,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143619504","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}
Pub Date : 2025-03-11DOI: 10.1016/j.jmmm.2025.172953
Xinyue Zhu , Xiaolong Yang , Yifan Wang , Wanhua Shi , Minmin Qiu
To study the wear mechanism of the magnetorheological brake, a set of composite disc magnetorheological brake system is proposed for easy disassembly and a brake wear mechanism experimental setup is constructed to experimentally study the effects of the number of braking times, the material of the brake disc, and the size of the magnetorheological fluid working clearance on the wear of the brake disc. The experimental results show that: with the increase of the number of braking times, the surface roughness of the brake disc gradually becomes smaller, the wear on the surface of the brake disc will worsen, and the braking torque of the magnetorheological brake will become larger. With the increase of the hardness of the brake disc, the surface wear of the brake disc will reduce accordingly. With the reduction of the magnetorheological fluid working clearance, the surface wear of the brake disc will worsen accordingly. The results of this study are of great significance for the improvement of the service life of the magnetorheological brake.
{"title":"Study on the wear mechanism of the composite disk magnetorheological brake","authors":"Xinyue Zhu , Xiaolong Yang , Yifan Wang , Wanhua Shi , Minmin Qiu","doi":"10.1016/j.jmmm.2025.172953","DOIUrl":"10.1016/j.jmmm.2025.172953","url":null,"abstract":"<div><div>To study the wear mechanism of the magnetorheological brake, a set of composite disc magnetorheological brake system is proposed for easy disassembly and a brake wear mechanism experimental setup is constructed to experimentally study the effects of the number of braking times, the material of the brake disc, and the size of the magnetorheological fluid working clearance on the wear of the brake disc. The experimental results show that: with the increase of the number of braking times, the surface roughness of the brake disc gradually becomes smaller, the wear on the surface of the brake disc will worsen, and the braking torque of the magnetorheological brake will become larger. With the increase of the hardness of the brake disc, the surface wear of the brake disc will reduce accordingly. With the reduction of the magnetorheological fluid working clearance, the surface wear of the brake disc will worsen accordingly. The results of this study are of great significance for the improvement of the service life of the magnetorheological brake.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"622 ","pages":"Article 172953"},"PeriodicalIF":2.5,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632163","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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