Pub Date : 2025-12-16DOI: 10.1016/j.jmmm.2025.173763
J. Taurines, N. Galopin
This study presents a new analytical model for isotropic magnetic hysteresis. It is thermodynamically consistent using an appropriate choice of evolution law for an internal variable that describes the dissipation of the material, in this case by introducing an irreversible part of the magnetic field. The paper also provides a detailed procedure for identifying the two hysteresis parameters. Soft and hard magnetic materials, as well as symmetric minor loops, were both tested successfully. The model is sufficiently flexible to be extended to anisotropic materials or to modify specific assumptions, such as the distribution of pinning sites.
{"title":"Analytical isotropic magnetic hysteresis modeling with two material hysteresis parameters","authors":"J. Taurines, N. Galopin","doi":"10.1016/j.jmmm.2025.173763","DOIUrl":"10.1016/j.jmmm.2025.173763","url":null,"abstract":"<div><div>This study presents a new analytical model for isotropic magnetic hysteresis. It is thermodynamically consistent using an appropriate choice of evolution law for an internal variable that describes the dissipation of the material, in this case by introducing an irreversible part of the magnetic field. The paper also provides a detailed procedure for identifying the two hysteresis parameters. Soft and hard magnetic materials, as well as symmetric minor loops, were both tested successfully. The model is sufficiently flexible to be extended to anisotropic materials or to modify specific assumptions, such as the distribution of pinning sites.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173763"},"PeriodicalIF":3.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760600","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 : 2025-12-15DOI: 10.1016/j.jmmm.2025.173744
Hyun Ho Park , Heehyuk Lee , YeongJun Park , Deuk-Kyu Hwang
This paper presents a regression based method to predict near-field magnetic shielding effectiveness (NSE) below 100 MHz using the real relative permeability and thickness of magnetic sheets. The relative permeability and NSE of commercial sheets were measured separately, with permeability measured using a Keysight 16454A test fixture and NSE measured using a microstrip line to generate the magnetic field and a loop probe for sensing. The measurement principles and procedures are described in detail to ensure reproducibility. Five polynomial regression models of frequency, real permeability, and thickness were developed from the measurement data using Minitab and applied to predict NSE. The accuracy of the models was evaluated by analyzing the mean square errors between measured and predicted values. Compared to numerical simulations that require substantial computational resources, this method provides accurate NSE predictions with minimal calculation time. This approach is both efficient and practical for the design and optimization of magnetic sheets where shielding is mainly determined by real permeability, and it can facilitate rapid material selection and performance estimation in engineering applications.
{"title":"Prediction of near-field shielding effectiveness for magnetic sheets by regression analysis","authors":"Hyun Ho Park , Heehyuk Lee , YeongJun Park , Deuk-Kyu Hwang","doi":"10.1016/j.jmmm.2025.173744","DOIUrl":"10.1016/j.jmmm.2025.173744","url":null,"abstract":"<div><div>This paper presents a regression based method to predict near-field magnetic shielding effectiveness (NSE) below 100 MHz using the real relative permeability and thickness of magnetic sheets. The relative permeability and NSE of commercial sheets were measured separately, with permeability measured using a Keysight 16454A test fixture and NSE measured using a microstrip line to generate the magnetic field and a loop probe for sensing. The measurement principles and procedures are described in detail to ensure reproducibility. Five polynomial regression models of frequency, real permeability, and thickness were developed from the measurement data using Minitab and applied to predict NSE. The accuracy of the models was evaluated by analyzing the mean square errors between measured and predicted values. Compared to numerical simulations that require substantial computational resources, this method provides accurate NSE predictions with minimal calculation time. This approach is both efficient and practical for the design and optimization of magnetic sheets where shielding is mainly determined by real permeability, and it can facilitate rapid material selection and performance estimation in engineering applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173744"},"PeriodicalIF":3.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145838535","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 : 2025-12-15DOI: 10.1016/j.jmmm.2025.173760
Tyler Paplham , Yuankang Wang , Alex Leary , Paul R. Ohodnicki
Transverse field- or stress-annealing of Co-rich nanocrystalline alloys is known to produce large induced magnetic anisotropies , associated with a highly sheared, linear hysteresis loop. This is attractive for extreme temperature (>300 °C) inductive applications such as in aerospace, since it precludes the need for gapping of the inductor, thus avoiding the use of impregnating resins with decomposition temperatures well below the target for operation. However, while previous studies have reported basic trends of anisotropy energy with temperature in these alloys, none have systematically explored effects of extended time at a given temperature, a critical aspect for components expected to operate near or above their primary crystallization temperature. Here we introduce the problem of extreme temperature magnetic stability and present results for the stability of both field- and stress-induced anisotropies as a function of time and temperature in a representative Co-rich chemistry up to 24 h. Possible mechanisms affecting anisotropy stability are identified and through comparison of microstructural and anisotropy evolution, associations between particular mechanisms and observed short- and long-term dynamics in the anisotropy are suggested.
{"title":"Extreme temperature stability of induced magnetic anisotropies in Co-rich soft magnetic nanocrystalline ribbon","authors":"Tyler Paplham , Yuankang Wang , Alex Leary , Paul R. Ohodnicki","doi":"10.1016/j.jmmm.2025.173760","DOIUrl":"10.1016/j.jmmm.2025.173760","url":null,"abstract":"<div><div>Transverse field- or stress-annealing of Co-rich nanocrystalline alloys is known to produce large induced magnetic anisotropies <span><math><msub><mi>K</mi><mi>u</mi></msub></math></span>, associated with a highly sheared, linear hysteresis loop. This is attractive for extreme temperature (>300 °C) inductive applications such as in aerospace, since it precludes the need for gapping of the inductor, thus avoiding the use of impregnating resins with decomposition temperatures well below the target for operation. However, while previous studies have reported basic trends of anisotropy energy with temperature in these alloys, none have systematically explored effects of extended time at a given temperature, a critical aspect for components expected to operate near or above their primary crystallization temperature. Here we introduce the problem of extreme temperature magnetic stability and present results for the stability of both field- and stress-induced anisotropies as a function of time and temperature in a representative Co-rich chemistry up to 24 h. Possible mechanisms affecting anisotropy stability are identified and through comparison of microstructural and anisotropy evolution, associations between particular mechanisms and observed short- and long-term dynamics in the anisotropy are suggested.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173760"},"PeriodicalIF":3.0,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145799259","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 : 2025-12-13DOI: 10.1016/j.jmmm.2025.173761
M. López-Cruz , J. Zamora , J.L. Sánchez Llamazares
This investigation highlights the effectiveness of Spark Plasma Sintering (SPS) for consolidating all-d-metal Ni-Co-Mn-Ti multicaloric alloys, which is significant for their potential applications. Highly dense sintered samples with a nominal composition of Ni37.5Co12.5Mn35Ti15 were prepared from single-phase melt-spun ribbon flakes used as precursors. The sintered samples exhibited essentially the same elemental chemical composition and phase transformation characteristics as the precursor, as confirmed by EDS analysis, thermomagnetic analysis, and differential scanning calorimetry. The martensitic transformation (MT) in both samples occurs from a B2-type cubic ferromagnetic austenite (AST) to a five-layer modulated (5 M) monoclinic antiferromagnetic martensite (MST) without a significant change in the initial and final temperatures of the structural transition. For a magnetic field change of 0–2 T, SPS samples showed a maximum magnetic-field-induced isothermal entropy change │ΔST│max of 8.6 J∙kg−1∙K−1 for the MST to AST transformation, which is comparable to that reported by other authors.
{"title":"Spark plasma sintering consolidation of all-d-metal Ni-Co-Mn-Ti alloys from melt-spun ribbons: magnetostructural and magnetocaloric characterization","authors":"M. López-Cruz , J. Zamora , J.L. Sánchez Llamazares","doi":"10.1016/j.jmmm.2025.173761","DOIUrl":"10.1016/j.jmmm.2025.173761","url":null,"abstract":"<div><div>This investigation highlights the effectiveness of Spark Plasma Sintering (SPS) for consolidating all-d-metal Ni-Co-Mn-Ti multicaloric alloys, which is significant for their potential applications. Highly dense sintered samples with a nominal composition of Ni<sub>37.5</sub>Co<sub>12.5</sub>Mn<sub>35</sub>Ti<sub>15</sub> were prepared from single-phase melt-spun ribbon flakes used as precursors. The sintered samples exhibited essentially the same elemental chemical composition and phase transformation characteristics as the precursor, as confirmed by EDS analysis, thermomagnetic analysis, and differential scanning calorimetry. The martensitic transformation (MT) in both samples occurs from a B2-type cubic ferromagnetic austenite (AST) to a five-layer modulated (5 M) monoclinic antiferromagnetic martensite (MST) without a significant change in the initial and final temperatures of the structural transition. For a magnetic field change of 0–2 T, SPS samples showed a maximum magnetic-field-induced isothermal entropy change │ΔS<sub>T</sub>│<sup>max</sup> of 8.6 J∙kg<sup>−1</sup>∙K<sup>−1</sup> for the MST to AST transformation, which is comparable to that reported by other authors.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173761"},"PeriodicalIF":3.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760603","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 : 2025-12-13DOI: 10.1016/j.jmmm.2025.173762
Adnan Khan , Guang Zeng , Yi-pei Zhang , Sha Lu , Cui-mei Cao , Ruo-shi Li , Shi-wei Chen , Shi-heng Liang
The spin-orbit torque (SOT) spintronic devices based on spin-orbit coupling (SOC) effects exhibit properties such as non-volatility, reversibility, high speed, and scalability. Reducing the switching power dissipation in SOT devices is a critical research focus. To address this, we modulated perpendicular magnetization switching by incorporating heavy metals Pt and Ta into ferrimagnetic CoTb thin films. We investigated magnetic field-driven domain wall motion and SOT-induced perpendicular magnetization switching in the ferrimagnetic layer. Our findings reveal that the introduction of Ta or Pt has limited impact on the domain wall pinning potential of CoTb. Notably, Ta-doped samples showed an increasing trend in the critical current density for SOT-driven magnetization switching, while Pt-doped samples exhibited a significant reduction in Jc. Further analysis of switching power dissipation across three sample types identified an approach to reduce energy consumption and enhance switching efficiency in ferrimagnetic systems. This work provides a promising pathway for advancing SOT-based device development.
{"title":"Ultra-low-power spin-orbit torque switching in heavy metal-doped CoTb ferrimagnets","authors":"Adnan Khan , Guang Zeng , Yi-pei Zhang , Sha Lu , Cui-mei Cao , Ruo-shi Li , Shi-wei Chen , Shi-heng Liang","doi":"10.1016/j.jmmm.2025.173762","DOIUrl":"10.1016/j.jmmm.2025.173762","url":null,"abstract":"<div><div>The spin-orbit torque (SOT) spintronic devices based on spin-orbit coupling (SOC) effects exhibit properties such as non-volatility, reversibility, high speed, and scalability. Reducing the switching power dissipation in SOT devices is a critical research focus. To address this, we modulated perpendicular magnetization switching by incorporating heavy metals Pt and Ta into ferrimagnetic CoTb thin films. We investigated magnetic field-driven domain wall motion and SOT-induced perpendicular magnetization switching in the ferrimagnetic layer. Our findings reveal that the introduction of Ta or Pt has limited impact on the domain wall pinning potential of CoTb. Notably, Ta-doped samples showed an increasing trend in the critical current density for SOT-driven magnetization switching, while Pt-doped samples exhibited a significant reduction in <em>J</em><sub>c</sub>. Further analysis of switching power dissipation across three sample types identified an approach to reduce energy consumption and enhance switching efficiency in ferrimagnetic systems. This work provides a promising pathway for advancing SOT-based device development.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173762"},"PeriodicalIF":3.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145799257","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}
In this study, we present a detailed magnetic investigation of the YFe2-xPtxSb2 (x = 0, 0.01, and 0.05) compounds synthesized via solid-state sintering. All samples crystallize in the ThCr2Si2-type structure (space group I4/mmm) at room temperature. Low-field DC magnetic susceptibility measurements were performed on all compositions. The compounds exhibit pronounced magnetic irreversibility at low fields below the coercivity, which is attributed to spin freezing at low temperatures. At elevated temperatures, their magnetic susceptibility follows the modified Curie–Weiss law with high accuracy. Magnetic analyses also indicate the onset of superconductivity below T ≈ 10 K.
The critical current density (Jc) and the normalized pinning force (Fp/Fp,max) were systematically examined as functions of the applied magnetic field. Furthermore, the Fp/Fp,max curves plotted against the reduced field h = H/Hirr scale well according to the Dew–Hughes model.
Finally, the magnetic state of YFe2Sb2 is shown to be strongly influenced by both composition and annealing conditions. High-temperature annealing enhances magnetization by increasing Fe occupancy on the Fe sites, thereby favoring full Fe ordering.
在这项研究中，我们对通过固态烧结合成的YFe2-xPtxSb2 （x = 0,0.01和0.05）化合物进行了详细的磁性研究。所有样品在室温下结晶为thcr2si2型结构（空间群I4/mmm）。对所有成分进行了低场直流磁化率测定。该化合物在低于矫顽力的低磁场下表现出明显的磁不可逆性，这归因于低温下的自旋冻结。在高温下，它们的磁化率符合修正的居里-魏斯定律，精度很高。磁性分析也表明，在T≈10 K以下开始出现超导性。系统研究了临界电流密度（Jc）和归一化钉钉力（Fp/Fp,max）随外加磁场的变化规律。此外，根据Dew-Hughes模型，绘制的Fp/Fp，max曲线与简化场h = h /Hirr的比例很好。结果表明，YFe2Sb2的磁态受成分和退火条件的强烈影响。高温退火通过增加铁在铁位上的占比来增强磁化强度，从而有利于铁的完全有序。
{"title":"Magnetic and structural properties of novel YFe2-xPtxSb2 (x = 0, 0.01, 0.05) compounds","authors":"Cihat Boyraz , Adil Guler , Perihan Aksu , Yildirhan Oner","doi":"10.1016/j.jmmm.2025.173758","DOIUrl":"10.1016/j.jmmm.2025.173758","url":null,"abstract":"<div><div>In this study, we present a detailed magnetic investigation of the YFe<sub>2-x</sub>Pt<sub>x</sub>Sb<sub>2</sub> (x = 0, 0.01, and 0.05) compounds synthesized via solid-state sintering. All samples crystallize in the <em>ThCr</em><sub><em>2</em></sub><em>Si</em><sub><em>2</em></sub>-type structure (space group <em>I4/mmm</em>) at room temperature. Low-field DC magnetic susceptibility measurements were performed on all compositions. The compounds exhibit pronounced magnetic irreversibility at low fields below the coercivity, which is attributed to spin freezing at low temperatures. At elevated temperatures, their magnetic susceptibility follows the modified Curie–Weiss law with high accuracy. Magnetic analyses also indicate the onset of superconductivity below <em>T</em> ≈ 10 K.</div><div>The critical current density (<em>J</em><sub><em>c</em></sub>) and the normalized pinning force (<em>F</em><sub><em>p</em></sub><em>/F</em><sub><em>p,</em>max</sub>) were systematically examined as functions of the applied magnetic field. Furthermore, the <em>F</em><sub><em>p</em></sub><em>/F</em><sub><em>p,max</em></sub> curves plotted against the reduced field <em>h = H/H</em><sub><em>irr</em></sub> scale well according to the Dew–Hughes model.</div><div>Finally, the magnetic state of YFe<sub>2</sub>Sb<sub>2</sub> is shown to be strongly influenced by both composition and annealing conditions. High-temperature annealing enhances magnetization by increasing Fe occupancy on the Fe sites, thereby favoring full Fe ordering.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173758"},"PeriodicalIF":3.0,"publicationDate":"2025-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787262","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 : 2025-12-11DOI: 10.1016/j.jmmm.2025.173756
G. Palai , D.P. Sahu , A. Mohanty , C. Mahapatra , Md.F. Abdullah , A.K. Singh
This article investigates the room temperature (RT) magnetodielectric (MD), electric, magnetic, and structural characteristics of Co doped Y-type hexaferrite Ba2Mg2-xCoxFe12O22 ( 0, 0.5, 1.0, 1.5) (BMCF) prepared by the sol-gel auto combustion method. According to the Rietveld refinement of the XRD patterns, all samples exhibit phase purity and crystallize in a rhombohedral structure with the space group R-3m. UV–visible spectroscopy measurement shows that all the samples exhibit a direct bandgap, and the bandgap value decreased from 1.35 eV (, BMF) to 1.22 eV ( 1.5, BMCF75). Temperature-dependent magnetization suggests that the ferrimagnetic to paramagnetic transition temperature () increased from 627 K for BMF to 735 K for BMCF75. Field-dependent magnetization measurements at 300 K reveal that saturation magnetization, remnant magnetization, and coercivity value are enhanced to ∼26.1035 emu/g, ∼4.3677 emu/g, and ∼90.9104 Oe for BMCF75. Magnetocrystalline anisotropy increased to 4 % for BMCF25 ( 0.5), 20 % for BMCF50 ( 1.0), and 24 % for BMCF75 compared to BMF. Using a Nyquist plot to assess impedance data, it is found that the relaxation process is related to the charge carriers. Activation energy () is calculated by using the Arrhenius equation. The observed Value for bare BMF is 0.224 ± 0.018 eV, and BMCF25 shows a higher value of 0.385 ± 0.021 eV due to higher grain boundary contribution. Frequency-dependent MD coupling exhibits a higher value of ∼6.94 % for BMCF75 at a frequency of 100 Hz. The field-dependent MD effect exhibits a narrow butterfly hysteresis loop for BMCF50 with a coupling of 0.28 %. This feature is valuable in applications like magnetic field sensors and energy harvesting devices.
{"title":"Enhanced magnetodielectric coupling in Co doped Y-type barium hexaferrites at room temperature","authors":"G. Palai , D.P. Sahu , A. Mohanty , C. Mahapatra , Md.F. Abdullah , A.K. Singh","doi":"10.1016/j.jmmm.2025.173756","DOIUrl":"10.1016/j.jmmm.2025.173756","url":null,"abstract":"<div><div>This article investigates the room temperature (RT) magnetodielectric (MD), electric, magnetic, and structural characteristics of Co doped Y-type hexaferrite Ba<sub>2</sub>Mg<sub><em>2-x</em></sub>Co<sub><em>x</em></sub>Fe<sub>12</sub>O<sub>22</sub> (<span><math><mi>x</mi><mo>=</mo></math></span> 0, 0.5, 1.0, 1.5) (BMCF) prepared by the sol-gel auto combustion method. According to the Rietveld refinement of the XRD patterns, all samples exhibit phase purity and crystallize in a rhombohedral structure with the space group <em>R-3m.</em> UV–visible spectroscopy measurement shows that all the samples exhibit a direct bandgap, and the bandgap value decreased from 1.35 eV (<span><math><mi>x</mi><mo>=</mo><mn>0</mn></math></span>, BMF) to 1.22 eV (<span><math><mi>x</mi><mo>=</mo></math></span> 1.5, BMCF75). Temperature-dependent magnetization suggests that the ferrimagnetic to paramagnetic transition temperature (<span><math><msub><mi>T</mi><mi>C</mi></msub></math></span>) increased from 627 K for BMF to 735 K for BMCF75. Field-dependent magnetization measurements at 300 K reveal that saturation magnetization, remnant magnetization, and coercivity value are enhanced to ∼26.1035 emu/g, ∼4.3677 emu/g, and ∼90.9104 Oe for BMCF75. Magnetocrystalline anisotropy increased to 4 % for BMCF25 (<span><math><mi>x</mi><mo>=</mo></math></span> 0.5), 20 % for BMCF50 (<span><math><mi>x</mi><mo>=</mo></math></span> 1.0), and 24 % for BMCF75 compared to BMF. Using a Nyquist plot to assess impedance data, it is found that the relaxation process is related to the charge carriers. Activation energy (<span><math><msub><mi>E</mi><mi>a</mi></msub></math></span>) is calculated by using the Arrhenius equation. The observed <span><math><msub><mi>E</mi><mi>a</mi></msub></math></span> Value for bare BMF is 0.224 ± 0.018 eV, and BMCF25 shows a higher value of 0.385 ± 0.021 eV due to higher grain boundary contribution. Frequency-dependent MD coupling exhibits a higher value of ∼6.94 % for BMCF75 at a frequency of 100 Hz. The field-dependent MD effect exhibits a narrow butterfly hysteresis loop for BMCF50 with a coupling of 0.28 %. This feature is valuable in applications like magnetic field sensors and energy harvesting devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173756"},"PeriodicalIF":3.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733723","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 : 2025-12-11DOI: 10.1016/j.jmmm.2025.173757
Pamulapati Soujanya , Nitish Ghosh , Subhadip Paul , Debajit Deb
We demonstrate defect-mediated charge and spin transport in a p-Si/CoFeO/Alq/Al heterostructure under the impact of bias, light intensity, and magnetic field. Light intensity-dependent current measurements, when probed at a specific DC voltage, show asymmetric response between forward (–1 V +1 V) and reverse (+1 V –1 V) voltage sweeps. At small negative biases, asymmetry reduced due to partial trap involvement, while positive biases enhance trap filling in the forward sweep and detrapping in the reverse sweep, amplifying the asymmetric response. Under an applied magnetic field, spin–flip scattering is suppressed, stabilizing transport thereby making light dependent current response deviate more towards symmetric response for both voltage sweep directions. Modeling of the response using a multi-step phonon-assisted tunneling mechanism reveals that these transport channels are governed by the energetic depth of traps. These results demonstrate that magnetic field dependent control of photo-response allows stable and spin-coherent transport across CFO/Alq hybrid interfaces, which can be employed for magneto-optic spintronic sensor applications.
{"title":"Magnetic field mediated asymmetry of current–light intensity response at CoFe2O4/Alq3 spintronic interface","authors":"Pamulapati Soujanya , Nitish Ghosh , Subhadip Paul , Debajit Deb","doi":"10.1016/j.jmmm.2025.173757","DOIUrl":"10.1016/j.jmmm.2025.173757","url":null,"abstract":"<div><div>We demonstrate defect-mediated charge and spin transport in a p-Si/CoFe<span><math><msub><mrow></mrow><mrow><mn>2</mn></mrow></msub></math></span>O<span><math><msub><mrow></mrow><mrow><mn>4</mn></mrow></msub></math></span>/Alq<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span>/Al heterostructure under the impact of bias, light intensity, and magnetic field. Light intensity-dependent current measurements, when probed at a specific DC voltage, show asymmetric response between forward (–1 V <span><math><mo>→</mo></math></span> +1 V) and reverse (+1 V <span><math><mo>→</mo></math></span> –1 V) voltage sweeps. At small negative biases, asymmetry reduced due to partial trap involvement, while positive biases enhance trap filling in the forward sweep and detrapping in the reverse sweep, amplifying the asymmetric response. Under an applied magnetic field, spin–flip scattering is suppressed, stabilizing transport thereby making light dependent current response deviate more towards symmetric response for both voltage sweep directions. Modeling of the response using a multi-step phonon-assisted tunneling mechanism reveals that these transport channels are governed by the energetic depth of traps. These results demonstrate that magnetic field dependent control of photo-response allows stable and spin-coherent transport across CFO/Alq<span><math><msub><mrow></mrow><mrow><mn>3</mn></mrow></msub></math></span> hybrid interfaces, which can be employed for magneto-optic spintronic sensor applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173757"},"PeriodicalIF":3.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733821","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 : 2025-12-11DOI: 10.1016/j.jmmm.2025.173759
Neeraj Kumar , Sanjay Pant , Kuldeep Singh
The structural, electrical, and magnetic properties of La0.7Ca0.3Mn1−xMxO3 (M = Cr, Fe, Co) compounds have been systematically investigated. All these samples exist as multiphase with La0.87Ce0.13Mn0.95M0.05O3, CeO2 and Mn3O4 compound. This finding is corroborated by the simulated XRD data analysis results. Double transition in electrical properties is explained in terms of competition between double-exchange interaction (DE) and super-exchange interaction (SE). It is found that Mn, Cr, Fe, Co have enhanced tendency to grow SE interaction. The local ordering ferromagnetic clusters are embedded in the anti-ferromagnetic host and conduction follows the percolative path. These results highlight the role of Mn-site dopants in tuning phase competition, transport, and magnetic properties in hole-doped manganites.
{"title":"Effect of Cr, Fe, and Co doping on the structural, transport, and magnetic properties of La0.7Ca0.3Mn1−xMxO3 (M = Cr, Fe, Co) compounds","authors":"Neeraj Kumar , Sanjay Pant , Kuldeep Singh","doi":"10.1016/j.jmmm.2025.173759","DOIUrl":"10.1016/j.jmmm.2025.173759","url":null,"abstract":"<div><div>The structural, electrical, and magnetic properties of La<sub>0.7</sub>Ca<sub>0.3</sub>Mn<sub>1−x</sub>M<sub>x</sub>O<sub>3</sub> (M = Cr, Fe, Co) compounds have been systematically investigated. All these samples exist as multiphase with La<sub>0.87</sub>Ce<sub>0.13</sub>Mn<sub>0.95</sub>M<sub>0.05</sub>O<sub>3</sub>, CeO<sub>2</sub> and Mn<sub>3</sub>O<sub>4</sub> compound. This finding is corroborated by the simulated XRD data analysis results. Double transition in electrical properties is explained in terms of competition between double-exchange interaction (DE) and super-exchange interaction (SE). It is found that Mn, Cr, Fe, Co have enhanced tendency to grow SE interaction. The local ordering ferromagnetic clusters are embedded in the anti-ferromagnetic host and conduction follows the percolative path. These results highlight the role of Mn-site dopants in tuning phase competition, transport, and magnetic properties in hole-doped manganites.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173759"},"PeriodicalIF":3.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787263","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 : 2025-12-11DOI: 10.1016/j.jmmm.2025.173755
J. Griffiths , O.P. Brooks , V. Kozak , W. Xia , H. Kitaguchi , D. Brown , A. Campbell , A. Lambourne , R.S. Sheridan
Sm2TM17 sintered magnets (TM = Co, Fe, Cu, Zr) have been utilised in high temperature electrical machine rotor applications as they have exceptionally stable magnetic properties at 200–350 °C. Sm and Co are critical elements and reliance on the virgin material supply chain must be reduced. Recycling Sm2TM17 magnets from end-of-life applications (EoL) via a hydrogen decrepitation (HD) processing route could be a potential solution and was the focus of this study.
Sm2TM17 magnets were exposed to 2–10 bar pressure at 100 °C for 72 h either loose or constrained within a rotor assembly. The hydrogen absorption/desorption behaviour, unit cell expansion and magnetic properties of the resulting powders were investigated.
Loose and constrained magnets absorbed similar amounts of hydrogen (0.195–0.233 Wt%), with unit cell volume increasing by 1.35–1.87 %, and all samples reached maximum hydrogen desorption at 180–210 °C. Magnets constrained within the rotor assembly were embrittled after HD but required further mechanical agitation to form a powder. Therefore, hydrogen uptake was not impeded by physical constraint, but crack propagation was hampered. Magnetised rotors did not demagnetise during HD but did exhibit reduced magnetic properties. Lattice strain caused by hydrogen uptake may have interfered with magnetic exchange coupling without destroying the domain wall pinning coercivity mechanism.
This study illustrated that HD processing is a potentially viable recycling route for Sm2TM17 sintered magnets, however a combination of mechanical agitation and a demagnetisation step will be required for the most efficient recovery of Sm2TM17 sintered magnets from EoL applications.
{"title":"Hydrogen decrepitation of Sm2TM17 sintered magnets from scrap rotor assemblies","authors":"J. Griffiths , O.P. Brooks , V. Kozak , W. Xia , H. Kitaguchi , D. Brown , A. Campbell , A. Lambourne , R.S. Sheridan","doi":"10.1016/j.jmmm.2025.173755","DOIUrl":"10.1016/j.jmmm.2025.173755","url":null,"abstract":"<div><div>Sm<sub>2</sub>TM<sub>17</sub> sintered magnets (TM = Co, Fe, Cu, Zr) have been utilised in high temperature electrical machine rotor applications as they have exceptionally stable magnetic properties at 200–350 °C. Sm and Co are critical elements and reliance on the virgin material supply chain must be reduced. Recycling Sm<sub>2</sub>TM<sub>17</sub> magnets from end-of-life applications (EoL) via a hydrogen decrepitation (HD) processing route could be a potential solution and was the focus of this study.</div><div>Sm<sub>2</sub>TM<sub>17</sub> magnets were exposed to 2–10 bar pressure at 100 °C for 72 h either loose or constrained within a rotor assembly. The hydrogen absorption/desorption behaviour, unit cell expansion and magnetic properties of the resulting powders were investigated.</div><div>Loose and constrained magnets absorbed similar amounts of hydrogen (0.195–0.233 Wt%), with unit cell volume increasing by 1.35–1.87 %, and all samples reached maximum hydrogen desorption at 180–210 °C. Magnets constrained within the rotor assembly were embrittled after HD but required further mechanical agitation to form a powder. Therefore, hydrogen uptake was not impeded by physical constraint, but crack propagation was hampered. Magnetised rotors did not demagnetise during HD but did exhibit reduced magnetic properties. Lattice strain caused by hydrogen uptake may have interfered with magnetic exchange coupling without destroying the domain wall pinning coercivity mechanism.</div><div>This study illustrated that HD processing is a potentially viable recycling route for Sm<sub>2</sub>TM<sub>17</sub> sintered magnets, however a combination of mechanical agitation and a demagnetisation step will be required for the most efficient recovery of Sm<sub>2</sub>TM<sub>17</sub> sintered magnets from EoL applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173755"},"PeriodicalIF":3.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760602","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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