Journal of Magnetism and Magnetic Materials最新文献

英文中文

Influence of silane coating and graphene oxide integration on the magnetothermal Behaviors of La1-xSrxMnO3 nanoparticles

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-18 DOI: 10.1016/j.jmmm.2025.172808

Buse Sert , Gul Kaya , Sinem Cicek , Ersan Harputlu , Telem Şimşek , Atakan Tekgül , C. Gokhan Unlu , Fatma Yurt , Kasim Ocakoglu

In this study, La_1-xSr_xMnO₃ (x = 0.27, 0.3, 0.33) magnetic nanoparticles (MNPs) were synthesized and then these nanoparticles synthesized in the core–shell structure were coated with silane for potential magnetic hyperthermia applications. In order to provide support material for the coated magnetic nanoparticles, silane-coated hybrid magnetic nanoparticles were obtained by producing graphene oxide (GO) nanoflakes. The structural and magnetic properties and magnetothermal properties of these structures were investigated. It was observed that the structure of the silane-coated magnetic nanoparticles remained intact and did not show any degradation compared to the uncoated materials. In addition, the highest saturation magnetization (M_S) value was observed in the sample doped with x = 0.30. This value indicated that the heating power would be higher than the other doped samples in the specific absorption ratio (SAR) measurements. In this context, the heating amount in the silane-coated samples showed a slight decrease compared to the uncoated samples. Despite the decrease in the SAR values of the integrated samples by incorporating GO into the coated MNPs, it is anticipated that effective results will be obtained for practical applications with the advantage of increasing the thermal conductivity of GO.

{"title":"Influence of silane coating and graphene oxide integration on the magnetothermal Behaviors of La1-xSrxMnO3 nanoparticles","authors":"Buse Sert , Gul Kaya , Sinem Cicek , Ersan Harputlu , Telem Şimşek , Atakan Tekgül , C. Gokhan Unlu , Fatma Yurt , Kasim Ocakoglu","doi":"10.1016/j.jmmm.2025.172808","DOIUrl":"10.1016/j.jmmm.2025.172808","url":null,"abstract":"<div><div>In this study, La<sub>1-x</sub>Sr<sub>x</sub>MnO<sub>3</sub> (x = 0.27, 0.3, 0.33) magnetic nanoparticles (MNPs) were synthesized and then these nanoparticles synthesized in the core–shell structure were coated with silane for potential magnetic hyperthermia applications. In order to provide support material for the coated magnetic nanoparticles, silane-coated hybrid magnetic nanoparticles were obtained by producing graphene oxide (GO) nanoflakes. The structural and magnetic properties and magnetothermal properties of these structures were investigated. It was observed that the structure of the silane-coated magnetic nanoparticles remained intact and did not show any degradation compared to the uncoated materials. In addition, the highest saturation magnetization (<em>M<sub>S</sub></em>) value was observed in the sample doped with x = 0.30. This value indicated that the heating power would be higher than the other doped samples in the specific absorption ratio (SAR) measurements. In this context, the heating amount in the silane-coated samples showed a slight decrease compared to the uncoated samples. Despite the decrease in the SAR values of the integrated samples by incorporating GO into the coated MNPs, it is anticipated that effective results will be obtained for practical applications with the advantage of increasing the thermal conductivity of GO.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172808"},"PeriodicalIF":2.5,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098416","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

Dynamics of current-driven spin waves in a confined track

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-18 DOI: 10.1016/j.jmmm.2025.172800

Yunxi Jiang , Xi Chen , Chen Xuan , Hem Raj Sharma , Hao Yu

This study investigates the generation, propagation, and decay of current-induced spin waves in a confined magnetic track through both theoretical analysis and numerical simulations. We derive an analytical expression for the spin wave dispersion and amplitude, establishing a linear relationship between the applied current density and the emitted wave frequency. The results reveal a deviation between the spin wave propagation direction and the current direction. As the spin waves decay, domain walls are generated in the system, with the number of domain walls being controlled by the current density and pulse duration. This research has promising applications in the field of spintronic devices, where controlled spin wave dynamics and domain wall creation could improve information processing and data storage. By tuning current-induced spin waves, these findings may support the development of magnetic memory elements, logic devices, and neuromorphic computing architectures that use domain walls for non-volatile memory and reconfigurable processing capabilities.

引用次数: 0

Evolution of the ground state of Yb ion in YbCu5-xSnx

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-18 DOI: 10.1016/j.jmmm.2025.172804

F. Akbar , I. Čurlík , J. Kúdelčík , M. Reiffers , M. Giovannini

Structural and magnetic studies have been carried out for the cubic YbCu_5-xSn_x system of the MgCu₄Sn-type, which exists in the solubility range 0.2 ≤ x ≤ 0.7. The magnetic properties of this system were compared with those of the analogous system YbCu_5-xIn_x (0.1 ≤ x ≤ 1.0). These two systems appear to share the same scenario of evolution from a localized trivalent state of the Yb atom for low values of x(x = 0.2) to valence transition state in a wide temperature range (T ∼ 40–80 K) for intermediate values of x(x = 0.6, 0.7). Specific heat measurements performed for one of these compositions, YbCu_4.4Sn_0.6, show an increase at low temperatures T < 7 K most probably due to the presence of a high density of magnetic excitations.

引用次数: 0

An investigation of tribological properties of magnetorheological grease with thermomagnetic coupling

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-18 DOI: 10.1016/j.jmmm.2025.172809

Jiabao Pan , Junjie Wang , Jin Wang , Guangxin Yang , Xiaolei Wang

Frictional and wear between components in magnetorheological devices critically influence on the operating stability, control accuracy, and service life. In particular, wear of the elastic seals may cause medium leakage and eventually lead to seal failure. This paper aims to investigate the tribological properties of magnetorheological grease with different thermomagnetic coupling conditions. First, a simulation analysis of the magnetic field distribution surrounding the friction subsurface is presented. Then, the tribological experiments are performed. Subsequently, experimental results and an ultra-depth digital microscope interactive system were combined to reveal thermomagnetic coupling lubrication mechanism. The experimental results indicate that different thermomagnetic coupling fields affect the tribological properties of magnetorheological grease and the magnetic field could compensate for the effect of temperature rise. The magnetic particles covered by the base oil will participate in the lubrication process. Moreover, the dispersed magnetic particles act as an intermediate layer and change the contact form in the friction area, thus reducing the friction coefficient. However, if the magnetic particles are agglomerated in large quantities, it may cause abrasive wear and increase the wear of the contact surface.

{"title":"An investigation of tribological properties of magnetorheological grease with thermomagnetic coupling","authors":"Jiabao Pan , Junjie Wang , Jin Wang , Guangxin Yang , Xiaolei Wang","doi":"10.1016/j.jmmm.2025.172809","DOIUrl":"10.1016/j.jmmm.2025.172809","url":null,"abstract":"<div><div>Frictional and wear between components in magnetorheological devices critically influence on the operating stability, control accuracy, and service life. In particular, wear of the elastic seals may cause medium leakage and eventually lead to seal failure. This paper aims to investigate the tribological properties of magnetorheological grease with different thermomagnetic coupling conditions. First, a simulation analysis of the magnetic field distribution surrounding the friction subsurface is presented. Then, the tribological experiments are performed. Subsequently, experimental results and an ultra-depth digital microscope interactive system were combined to reveal thermomagnetic coupling lubrication mechanism. The experimental results indicate that different thermomagnetic coupling fields affect the tribological properties of magnetorheological grease and the magnetic field could compensate for the effect of temperature rise. The magnetic particles covered by the base oil will participate in the lubrication process. Moreover, the dispersed magnetic particles act as an intermediate layer and change the contact form in the friction area, thus reducing the friction coefficient. However, if the magnetic particles are agglomerated in large quantities, it may cause abrasive wear and increase the wear of the contact surface.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172809"},"PeriodicalIF":2.5,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098421","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

Metrological determination of the soft magnetic properties of slot wedge material in electrical machines

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-17 DOI: 10.1016/j.jmmm.2025.172801

Florian Kirchner , Andreas Kremser

Soft magnetic slot wedges as a composite of iron powder, resin and glass fiber are used to close the slots for the winding in electrical machines. Due to their magnetic properties, they influence the magnetic air gap field and the stray behavior of the electrical machine. By precisely dimensioning the material parameters, a reduction in the additional no-load losses and respectively an increase in the efficiency of the machines can be achieved. The determination and validation of the material properties are essential for the development of suitable materials and machine models. This document presents a measurement method for determining the magnetization curve and total losses, which in particular also enables the application to anisotropic materials as well as powders and pastes. The method was validated by comparative measurements using a standardized measurement method. After validation, various slot wedge materials were tested, and the results compared. It is shown that the magnetization curve and the total losses are depending on the filler share of soft magnetic particles. Using the specialized measurement setup, it was also found that some traditional soft magnetic slot wedge materials show anisotropic characteristics. In machine models with soft magnetic slot wedges, the investigated anisotropy as well as the total losses have not been considered in detail yet.

{"title":"Metrological determination of the soft magnetic properties of slot wedge material in electrical machines","authors":"Florian Kirchner , Andreas Kremser","doi":"10.1016/j.jmmm.2025.172801","DOIUrl":"10.1016/j.jmmm.2025.172801","url":null,"abstract":"<div><div>Soft magnetic slot wedges as a composite of iron powder, resin and glass fiber are used to close the slots for the winding in electrical machines. Due to their magnetic properties, they influence the magnetic air gap field and the stray behavior of the electrical machine. By precisely dimensioning the material parameters, a reduction in the additional no-load losses and respectively an increase in the efficiency of the machines can be achieved. The determination and validation of the material properties are essential for the development of suitable materials and machine models. This document presents a measurement method for determining the magnetization curve and total losses, which in particular also enables the application to anisotropic materials as well as powders and pastes. The method was validated by comparative measurements using a standardized measurement method. After validation, various slot wedge materials were tested, and the results compared. It is shown that the magnetization curve and the total losses are depending on the filler share of soft magnetic particles. Using the specialized measurement setup, it was also found that some traditional soft magnetic slot wedge materials show anisotropic characteristics. In machine models with soft magnetic slot wedges, the investigated anisotropy as well as the total losses have not been considered in detail yet.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172801"},"PeriodicalIF":2.5,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149702","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

Influence of excitation parameters on the magnetization of MFL ILI tools for small-diameter pipelines

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-16 DOI: 10.1016/j.jmmm.2025.172780

Jia Zhang , Lin Qin , Mingnan Sun , Dong Lin , Chang Liu , Zhaoming Zhou

Magnetic flux leakage (MFL) method has been widely applied for the detection and localization of defects in pipes with nominal diameters greater than 6-inch, due to its high detection efficiency. In small-diameter pipelines, where space is constrained, achieving a high magnetic flux is vital for enhancing the sensitivity and reliability of defect detection. A well-designed excitation unit significantly improves the coupling between permanent magnets and the pipeline material, thereby maximizing the induced magnetization within the pipe wall. This aspect is particularly crucial for applications involving small-diameter pipelines ILI. The primary objective of this study is to identify the optimal dimensional parameters of the excitation unit for 4-inch MFL tools. The finite element method (FEM) was employed to analyze the evolution patterns of the magnetic field at defect sites across various operational parameters. Key factors influencing magnetization capability were examined, including magnetic core diameter, permanent magnet dimensions, lift-off height, pipe wall thickness, and operational speed. Additionally, the relationships between these influencing factors within the magnetic circuit and the induced magnetic field in the pipe wall were established. A fitting analysis of the characteristic signals was also conducted. The findings provide valuable insights into maximizing information utilization within limited space and establishing a balance between detection quality and signal precision. It is of great significance to promote the development of safety detection technology for small-diameter pipelines.

{"title":"Influence of excitation parameters on the magnetization of MFL ILI tools for small-diameter pipelines","authors":"Jia Zhang , Lin Qin , Mingnan Sun , Dong Lin , Chang Liu , Zhaoming Zhou","doi":"10.1016/j.jmmm.2025.172780","DOIUrl":"10.1016/j.jmmm.2025.172780","url":null,"abstract":"<div><div>Magnetic flux leakage (MFL) method has been widely applied for the detection and localization of defects in pipes with nominal diameters greater than 6-inch, due to its high detection efficiency. In small-diameter pipelines, where space is constrained, achieving a high magnetic flux is vital for enhancing the sensitivity and reliability of defect detection. A well-designed excitation unit significantly improves the coupling between permanent magnets and the pipeline material, thereby maximizing the induced magnetization within the pipe wall. This aspect is particularly crucial for applications involving small-diameter pipelines ILI. The primary objective of this study is to identify the optimal dimensional parameters of the excitation unit for 4-inch MFL tools. The finite element method (FEM) was employed to analyze the evolution patterns of the magnetic field at defect sites across various operational parameters. Key factors influencing magnetization capability were examined, including magnetic core diameter, permanent magnet dimensions, lift-off height, pipe wall thickness, and operational speed. Additionally, the relationships between these influencing factors within the magnetic circuit and the induced magnetic field in the pipe wall were established. A fitting analysis of the characteristic signals was also conducted. The findings provide valuable insights into maximizing information utilization within limited space and establishing a balance between detection quality and signal precision. It is of great significance to promote the development of safety detection technology for small-diameter pipelines.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"616 ","pages":"Article 172780"},"PeriodicalIF":2.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164783","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

Baromagnetic, magnetostrain and magnetocaloric properties in Ni54FeMn20Ga25 alloy

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-16 DOI: 10.1016/j.jmmm.2025.172806

Yuanlei Zhang , Meilan Dai , Hongwei Liu , Shengxian Wei , Kun Xu , Yiming Cao , Zhe Li , Chao Jing

The crystalline structure, martensitic transformation, strain behavior, and the effect of hydrostatic pressure on magnetocrystalline anisotropy and magnetocaloric effect have been comprehensively investigated using various experimental methods in a polycrystalline Ni₅₄FeMn₂₀Ga₂₆ Heusler alloy. It is shown that the studied alloy possesses a coexistence phase of L2₁ cubic austenite and seven-layer modulated orthorhombic martensite at room temperature. Under low magnetic fields, the alloy undergoes a ferromagnetically martensitic transformation from the ferromagnetic austenite to the weakly ferromagnetic martensite with decreasing temperature, accompanied by a pseudo-decrease in magnetization. Meanwhile, an anti-baromagnetic effect was observed in the alloy, which can be attributed to the fact that when the applied pressure exceeds 8 kbar, the magnetocrystalline anisotropy constant decreases gradually with the increase of applied hydrostatic pressure. Benefiting from the rotation of magnetic domains within the martensitic variants possible, a considerable magnetostrain with a value of about 0.2 % was obtained under a magnetic field change of 3 T. In addition, the isothermal entropy change was calculated to be approximately −9.5 J/kg·K, yielding a refrigerant capacity of about 28 J/kg in the present alloy. The peak position of the isothermal entropy change shifts to higher temperatures, while the isothermal entropy change and refrigerant capacity decrease slightly under the application of hydrostatic pressure.

{"title":"Baromagnetic, magnetostrain and magnetocaloric properties in Ni54FeMn20Ga25 alloy","authors":"Yuanlei Zhang , Meilan Dai , Hongwei Liu , Shengxian Wei , Kun Xu , Yiming Cao , Zhe Li , Chao Jing","doi":"10.1016/j.jmmm.2025.172806","DOIUrl":"10.1016/j.jmmm.2025.172806","url":null,"abstract":"<div><div>The crystalline structure, martensitic transformation, strain behavior, and the effect of hydrostatic pressure on magnetocrystalline anisotropy and magnetocaloric effect have been comprehensively investigated using various experimental methods in a polycrystalline Ni<sub>54</sub>FeMn<sub>20</sub>Ga<sub>26</sub> Heusler alloy. It is shown that the studied alloy possesses a coexistence phase of <em>L</em>2<sub>1</sub> cubic austenite and seven-layer modulated orthorhombic martensite at room temperature. Under low magnetic fields, the alloy undergoes a ferromagnetically martensitic transformation from the ferromagnetic austenite to the weakly ferromagnetic martensite with decreasing temperature, accompanied by a pseudo-decrease in magnetization. Meanwhile, an anti-baromagnetic effect was observed in the alloy, which can be attributed to the fact that when the applied pressure exceeds 8 kbar, the magnetocrystalline anisotropy constant decreases gradually with the increase of applied hydrostatic pressure. Benefiting from the rotation of magnetic domains within the martensitic variants possible, a considerable magnetostrain with a value of about 0.2 % was obtained under a magnetic field change of 3 T. In addition, the isothermal entropy change was calculated to be approximately −9.5 J/kg·K, yielding a refrigerant capacity of about 28 J/kg in the present alloy. The peak position of the isothermal entropy change shifts to higher temperatures, while the isothermal entropy change and refrigerant capacity decrease slightly under the application of hydrostatic pressure.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172806"},"PeriodicalIF":2.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149703","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 effect of Fe-doping on martensitic transformation for Co50V34Ga16 Heusler alloys

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-16 DOI: 10.1016/j.jmmm.2025.172805

Junwei Tan , Yakun Liu , Yuetong Qian , Hongwei Liu , Wenying Yu , Tao Zhou , Zhe Li , Xiaodong Si , Yongsheng Liu

In this work, the Co₅₀Fe_xV_34-_xGa₁₆ (x = 1, 2, 3) Heusler alloys were prepared by arc melting. The martensitic transformation near room temperature was excited in the alloys. Owing to the Fe substitution, the alloys are more likely to stabilize in the low-temperature martensitic phase. Thermo-magnetization curves demonstrate that martensitic transformation temperatures increase and martensitic transformation entropy decreases with increasing Fe content. Additionally, the alloy exhibits a shape memory, and the value of strain decreases with increasing Fe content, with a maximum value of ∼ 0.32 % as x = 1.

引用次数: 0

Spin gapped metals: A novel class of materials for multifunctional spintronic devices

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-16 DOI: 10.1016/j.jmmm.2025.172792

E. Şaşıoğlu , M. Tas , S. Ghosh , W. Beida , B. Sanyal , S. Blügel , I. Mertig , I. Galanakis

Gapped metals, a recently proposed class of materials, possess a band gap slightly above or below the Fermi level, behaving as intrinsic p- or n-type semiconductors without requiring external doping. Inspired by this concept, we propose a novel material class: ”spin gapped metals”. These materials exhibit intrinsic p- or n-type character independently for each spin channel, similar to dilute magnetic semiconductors but without the need for transition metal doping. A key advantage of spin gapped metals lies in the absence of band tails that exist within the band gap of conventional p- and n-type semiconductors. Band tails degrade the performance of devices like tunnel field-effect transistors (causing high subthreshold slopes) and negative differential resistance tunnel diodes (resulting in low peak-to-valley current ratios). Here, we demonstrate the viability of spin gapped metals using first-principles electronic band structure calculations on half-Heusler compounds. Our analysis reveals compounds displaying both gapped metal and spin gapped metal behavior, paving the way for next-generation multifunctional devices in spintronics and nanoelectronics.

{"title":"Spin gapped metals: A novel class of materials for multifunctional spintronic devices","authors":"E. Şaşıoğlu , M. Tas , S. Ghosh , W. Beida , B. Sanyal , S. Blügel , I. Mertig , I. Galanakis","doi":"10.1016/j.jmmm.2025.172792","DOIUrl":"10.1016/j.jmmm.2025.172792","url":null,"abstract":"<div><div>Gapped metals, a recently proposed class of materials, possess a band gap slightly above or below the Fermi level, behaving as intrinsic p- or n-type semiconductors without requiring external doping. Inspired by this concept, we propose a novel material class: ”spin gapped metals”. These materials exhibit intrinsic p- or n-type character independently for each spin channel, similar to dilute magnetic semiconductors but without the need for transition metal doping. A key advantage of spin gapped metals lies in the absence of band tails that exist within the band gap of conventional p- and n-type semiconductors. Band tails degrade the performance of devices like tunnel field-effect transistors (causing high subthreshold slopes) and negative differential resistance tunnel diodes (resulting in low peak-to-valley current ratios). Here, we demonstrate the viability of spin gapped metals using first-principles electronic band structure calculations on half-Heusler compounds. Our analysis reveals compounds displaying both gapped metal and spin gapped metal behavior, paving the way for next-generation multifunctional devices in spintronics and nanoelectronics.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172792"},"PeriodicalIF":2.5,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098419","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

Phase composition and magnetic properties of SmCo5/Fe nanocomposite powder prepared by cryomilling

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

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-15 DOI: 10.1016/j.jmmm.2025.172790

Bangzhen Li , Shizhong An , Wuhui Li , Fengzhang Ren

Ball milling temperature is a significant factor influencing the phase composition and magnetic properties of ball-milled powders. We compare the morphology, phase composition and magnetic properties of SmCo₅ and SmCo₅/Fe powders produced through cryomilling and conventional milling techniques. Our findings indicate that cryomilling effectively inhibits cold welding and phase transformations, reduces contamination, and enhances the magnetic properties of powders compared with conventional ball milling. Larger sized particles formed due to cold welding were observed in conventional milled powders, while better dispersion was observed in cryomilled powders. Sm₂Co₁₇ phase appeared in the SmCo₅ powder after 12 h of conventional ball milling, while only an amorphous phase was found in the cryomilled one. When ball milling time was extended from 2 h to 12 h, the Fe content in the conventional milled SmCo₅ powder increased from 4.6 wt% to 7.9 wt%, which was much higher than that in the cryomilled SmCo₅ powder (from 1.4 wt% to 2.2 wt%). After 8 h of ball milling, the coercivity of the cryomilled SmCo₅ powder reached 3.01 kOe, representing a 64.48 % increase compared with that of the conventional milled powder. The saturation magnetization of cryomilled SmCo₅/Fe composite powder was 122.89 emu/g, which is 4.34 % higher than that of the conventional milling. As the annealing temperature increases from 500 °C to 700 °C, the main phase of the hard magnetic phase in the SmCo₅/Fe nanocomposite powders transformed from SmCo₃ phase to Sm₂Co₁₇ phase, and the content of the soft magnetic Fe(Co) phase is decreasing, and the coercivity is increasing. SmCo₅/Fe cryomilled magnetic powder annealed at 550 °C possesses a M_r of 79.63 emu/g, a M_r/M_s of 0.71, a H_c of 6.16 kOe, which are much higher than that of the conventional milled SmCo₅/Fe powder annealed at 550 °C. This work provides a ball milling process optimization strategy for the preparation of high performance nanocomposite magnets.

{"title":"Phase composition and magnetic properties of SmCo5/Fe nanocomposite powder prepared by cryomilling","authors":"Bangzhen Li , Shizhong An , Wuhui Li , Fengzhang Ren","doi":"10.1016/j.jmmm.2025.172790","DOIUrl":"10.1016/j.jmmm.2025.172790","url":null,"abstract":"<div><div>Ball milling temperature is a significant factor influencing the phase composition and magnetic properties of ball-milled powders. We compare the morphology, phase composition and magnetic properties of SmCo<sub>5</sub> and SmCo<sub>5</sub>/Fe powders produced through cryomilling and conventional milling techniques. Our findings indicate that cryomilling effectively inhibits cold welding and phase transformations, reduces contamination, and enhances the magnetic properties of powders compared with conventional ball milling. Larger sized particles formed due to cold welding were observed in conventional milled powders, while better dispersion was observed in cryomilled powders. Sm<sub>2</sub>Co<sub>17</sub> phase appeared in the SmCo<sub>5</sub> powder after 12 h of conventional ball milling, while only an amorphous phase was found in the cryomilled one. When ball milling time was extended from 2 h to 12 h, the Fe content in the conventional milled SmCo<sub>5</sub> powder increased from 4.6 wt% to 7.9 wt%, which was much higher than that in the cryomilled SmCo<sub>5</sub> powder (from 1.4 wt% to 2.2 wt%). After 8 h of ball milling, the coercivity of the cryomilled SmCo<sub>5</sub> powder reached 3.01 kOe, representing a 64.48 % increase compared with that of the conventional milled powder. The saturation magnetization of cryomilled SmCo<sub>5</sub>/Fe composite powder was 122.89 emu/g, which is 4.34 % higher than that of the conventional milling. As the annealing temperature increases from 500 °C to 700 °C, the main phase of the hard magnetic phase in the SmCo<sub>5</sub>/Fe nanocomposite powders transformed from SmCo<sub>3</sub> phase to Sm<sub>2</sub>Co<sub>17</sub> phase, and the content of the soft magnetic Fe(Co) phase is decreasing, and the coercivity is increasing. SmCo<sub>5</sub>/Fe cryomilled magnetic powder annealed at 550 °C possesses a M<sub>r</sub> of 79.63 emu/g, a M<sub>r</sub>/M<sub>s</sub> of 0.71, a H<sub>c</sub> of 6.16 kOe, which are much higher than that of the conventional milled SmCo<sub>5</sub>/Fe powder annealed at 550 °C. This work provides a ball milling process optimization strategy for the preparation of high performance nanocomposite magnets.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172790"},"PeriodicalIF":2.5,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098423","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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