Pub Date : 2025-11-21DOI: 10.1016/j.jmmm.2025.173697
Zepeng Wang , Qianzhen Su , Jin Chen , Chao Zhang , Bo Zhang , Xiaolong Wen , Jianhua Li
Amorphous wire sensors exhibit significant potential for magnetic bead-based biological detection applications due to their high sensitivity to magnetic fields. However, the flexibility and structural heterogeneity of amorphous microwires hinder their integration into MEMS processes, and their detection area restricts their effectiveness in biological detection applications. To overcome these limitations, we proposed a novel magnetic bead detection system based on the amorphous microwire GMI sensor. The sensor operates based on the off-diagonal magneto-impedance effect, detecting magnetic beads by measuring the voltage change in a pick-up coil. This system utilizes microfabricated grooves on glass substrates to enable precise alignment and fixation of the microwires. To expand the sensing area, an array configuration was adopted. The sensor exhibited a resolution of 0.75nT, a sensitivity of 5.997 V/Oe, and a linearity of 99.97 % within ±0.75 Oe range. Furthermore, by integrating microfluidic technology, we constructed a real-time detection system for monitoring magnetic bead solutions. This system can monitor magnetic bead solutions at concentrations ranging from 1 to 50 μg/ml over an area of 11 mm × 7 mm.
非晶丝传感器由于对磁场的高灵敏度，在基于磁珠的生物检测应用中表现出巨大的潜力。然而，非晶微线的灵活性和结构的非均质性阻碍了其在MEMS工艺中的集成，其检测面积也限制了其在生物检测中的应用。为了克服这些限制，我们提出了一种基于非晶微线GMI传感器的新型磁珠检测系统。该传感器基于非对角线磁阻抗效应工作，通过测量拾取线圈中的电压变化来检测磁珠。该系统利用玻璃基板上的微加工凹槽来实现微线的精确对准和固定。为了扩大传感面积，采用了阵列结构。该传感器的分辨率为0.75 nt，灵敏度为5.997 V/Oe，在±0.75 Oe范围内线性度为99.97%。结合微流控技术，构建了磁珠溶液实时检测系统。该系统可以在11 mm × 7 mm的区域内监测浓度范围为1至50 μg/ml的磁珠溶液。
{"title":"Arrayed amorphous wire sensing system for large-area magnetic beads detection","authors":"Zepeng Wang , Qianzhen Su , Jin Chen , Chao Zhang , Bo Zhang , Xiaolong Wen , Jianhua Li","doi":"10.1016/j.jmmm.2025.173697","DOIUrl":"10.1016/j.jmmm.2025.173697","url":null,"abstract":"<div><div>Amorphous wire sensors exhibit significant potential for magnetic bead-based biological detection applications due to their high sensitivity to magnetic fields. However, the flexibility and structural heterogeneity of amorphous microwires hinder their integration into MEMS processes, and their detection area restricts their effectiveness in biological detection applications. To overcome these limitations, we proposed a novel magnetic bead detection system based on the amorphous microwire GMI sensor. The sensor operates based on the off-diagonal magneto-impedance effect, detecting magnetic beads by measuring the voltage change in a pick-up coil. This system utilizes microfabricated grooves on glass substrates to enable precise alignment and fixation of the microwires. To expand the sensing area, an array configuration was adopted. The sensor exhibited a resolution of 0.75nT, a sensitivity of 5.997 V/Oe, and a linearity of 99.97 % within ±0.75 Oe range. Furthermore, by integrating microfluidic technology, we constructed a real-time detection system for monitoring magnetic bead solutions. This system can monitor magnetic bead solutions at concentrations ranging from 1 to 50 μg/ml over an area of 11 mm × 7 mm.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173697"},"PeriodicalIF":3.0,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621893","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 : 2025-11-21DOI: 10.1016/j.jmmm.2025.173698
Jinmin Ding , Qianni Yang , Zongkui Tian , Jian Sun , Qinglin Xia , Ziyan Luo , Guanghua Guo
As a fundamental unit of magnetic random-access memory, spin valve (SV) has attracted substantial attention. Recently, the development of transition metal dichalcogenides (TMDs) and van der Waals (vdW) ferromagnetic materials offers opportunities to build up all-vdW SV without dangling bonds. Here, we report SV effect observed in Fe5GeTe2/MoS2/Fe5GeTe2 device below 150 K. The platform width of this device at 10 K is 0.32 T, which is larger than that of most all-vdW SV devices. This increased platform width is attributed to the high sensitivity of the coercivity relying on Fe₅GeTe₂ thickness. Additionally, the magnetoresistance (MR) value of this device increases monotonically with decreasing temperature, reaching 0.68 % at 10 K, and the corresponding spin polarization is 5.4 %. The present work establishes a foundation for the development of all-vdW SV devices and multi-state memory.
{"title":"Investigation of spin valve effect on Fe5GeTe2/MoS2/Fe5GeTe2 van der Waals heterostructures","authors":"Jinmin Ding , Qianni Yang , Zongkui Tian , Jian Sun , Qinglin Xia , Ziyan Luo , Guanghua Guo","doi":"10.1016/j.jmmm.2025.173698","DOIUrl":"10.1016/j.jmmm.2025.173698","url":null,"abstract":"<div><div>As a fundamental unit of magnetic random-access memory, spin valve (SV) has attracted substantial attention. Recently, the development of transition metal dichalcogenides (TMDs) and van der Waals (vdW) ferromagnetic materials offers opportunities to build up all-vdW SV without dangling bonds. Here, we report SV effect observed in Fe<sub>5</sub>GeTe<sub>2</sub>/MoS<sub>2</sub>/Fe<sub>5</sub>GeTe<sub>2</sub> device below 150 K. The platform width of this device at 10 K is 0.32 T, which is larger than that of most all-vdW SV devices. This increased platform width is attributed to the high sensitivity of the coercivity relying on Fe₅GeTe₂ thickness. Additionally, the magnetoresistance (MR) value of this device increases monotonically with decreasing temperature, reaching 0.68 % at 10 K, and the corresponding spin polarization is 5.4 %. The present work establishes a foundation for the development of all-vdW SV devices and multi-state memory.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173698"},"PeriodicalIF":3.0,"publicationDate":"2025-11-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621891","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 : 2025-11-20DOI: 10.1016/j.jmmm.2025.173681
Indujan Sivanesarajah , Leon Abelmann , Uwe Hartmann
Thin-film giant magnetoimpedance (GMI) structures are promising candidates for high-frequency magnetic sensing, with their performance governed by the interplay of electronic transport, magnetic softness, and ferromagnetic resonance (FMR). Optimisation therefore requires a comprehensive understanding of the properties of soft magnetic materials. This study investigates the structural, electric, magnetic, and GMI properties of sputtered amorphous CoNbZr single layers, amorphous CoNbZr/Au multilayers, and crystalline NiFe/Au multilayers. GMI measurements reveal distinct FMR frequencies of 1.4 GHz (CoNbZr), 0.7 GHz (CoNbZr/Au), and 0.5 GHz (NiFe/Au). Introducing Au interlayers into CoNbZr lowers the FMR frequency by 50% and enhances the maximum GMI ratio by a comparable margin relative to the single-layer film. At 1.8 GHz, the highest GMI performance is observed in a CoNbZr/Au strip, yielding 300% with a sensitivity of 249%/kAm. Under identical conditions, single-layer CoNbZr reaches 180% (169%/kAm) and NiFe/Au 280% (183%/kAm), confirming the superior response of the CoNbZr/Au multilayer. These improvements are attributed to differences in in-plane demagnetising factors and saturation magnetisations, providing design guidelines for the development of resonant GHz-range GMI sensors.
{"title":"Magnetoimpedance properties of CoNbZr, multilayer CoNbZr/Au and multilayer NiFe/Au thin films","authors":"Indujan Sivanesarajah , Leon Abelmann , Uwe Hartmann","doi":"10.1016/j.jmmm.2025.173681","DOIUrl":"10.1016/j.jmmm.2025.173681","url":null,"abstract":"<div><div>Thin-film giant magnetoimpedance (GMI) structures are promising candidates for high-frequency magnetic sensing, with their performance governed by the interplay of electronic transport, magnetic softness, and ferromagnetic resonance (FMR). Optimisation therefore requires a comprehensive understanding of the properties of soft magnetic materials. This study investigates the structural, electric, magnetic, and GMI properties of sputtered amorphous CoNbZr single layers, amorphous CoNbZr/Au multilayers, and crystalline NiFe/Au multilayers. GMI measurements reveal distinct FMR frequencies of 1.4 GHz (CoNbZr), 0.7 GHz (CoNbZr/Au), and 0.5 GHz (NiFe/Au). Introducing Au interlayers into CoNbZr lowers the FMR frequency by 50% and enhances the maximum GMI ratio by a comparable margin relative to the single-layer film. At 1.8 GHz, the highest GMI performance is observed in a <span><math><mrow><mn>20</mn><mspace></mspace><mi>μ</mi><mi>m</mi><mo>×</mo><mn>5000</mn><mspace></mspace><mi>μ</mi><mi>m</mi></mrow></math></span> CoNbZr/Au strip, yielding 300% with a sensitivity of 249%/kAm<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>. Under identical conditions, single-layer CoNbZr reaches 180% (169%/kAm<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>) and NiFe/Au 280% (183%/kAm<span><math><msup><mrow></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></math></span>), confirming the superior response of the CoNbZr/Au multilayer. These improvements are attributed to differences in in-plane demagnetising factors and saturation magnetisations, providing design guidelines for the development of resonant GHz-range GMI sensors.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173681"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621892","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 : 2025-11-20DOI: 10.1016/j.jmmm.2025.173696
Ankush Saxena , Shiu-Ming Huang , Navneet Kumar Karn , Manish Mani Sharma , Kamal , Che-Min Lin , Mitch Chou , Veer Pal Singh Awana
In this study, we investigated the transport and magnetic behavior of MnSb2Te4, a magnetic topological insulator and structural analogue of MnBi2Te4. Single crystals of MnSb2Te4 were successfully synthesized using a solid-state reaction method. Structural characterization via X-ray diffraction and scanning electron microscopy confirms the phase purity and well-defined crystallinity of the samples. To further probe the lattice dynamics and chemical states, Raman spectroscopy and X-ray photoelectron spectroscopy were employed, revealing distinct vibrational modes and valence states of the constituent elements. Magnetization measurements uncover two distinct magnetic transitions, which are corroborated by temperature-dependent electrical transport data. The resistivity (ρ–T) profile suggests the presence of magnetic polarons, indicative of strong coupling between charge carriers and local magnetic moments. At low temperatures (T < 40 K), magnetoresistance (MR) measurements exhibit hysteresis as a function of magnetic field, pointing to the coexistence of ferromagnetic and antiferromagnetic phases. With increasing temperature, negative MR becomes prominent above the magnetic ordering point due to polaron formation. To gain deeper insight into the electronic structure, density functional theory (DFT) calculations were performed. These reveal a competition between ferromagnetic and antiferromagnetic interactions, underscoring the complex magnetic landscape of MnSb2Te4. Overall, our findings highlight MnSb2Te4 as a compelling system that hosts coexisting magnetic phases intertwined with topological characteristics, warranting further exploration of its magneto-topological coupling.
{"title":"Intrinsic coexistence of ferromagnetic and antiferromagnetic phases in MnSb2Te4 topological layers","authors":"Ankush Saxena , Shiu-Ming Huang , Navneet Kumar Karn , Manish Mani Sharma , Kamal , Che-Min Lin , Mitch Chou , Veer Pal Singh Awana","doi":"10.1016/j.jmmm.2025.173696","DOIUrl":"10.1016/j.jmmm.2025.173696","url":null,"abstract":"<div><div>In this study, we investigated the transport and magnetic behavior of MnSb<sub>2</sub>Te<sub>4</sub>, a magnetic topological insulator and structural analogue of MnBi<sub>2</sub>Te<sub>4</sub>. Single crystals of MnSb<sub>2</sub>Te<sub>4</sub> were successfully synthesized using a solid-state reaction method. Structural characterization via X-ray diffraction and scanning electron microscopy confirms the phase purity and well-defined crystallinity of the samples. To further probe the lattice dynamics and chemical states, Raman spectroscopy and X-ray photoelectron spectroscopy were employed, revealing distinct vibrational modes and valence states of the constituent elements. Magnetization measurements uncover two distinct magnetic transitions, which are corroborated by temperature-dependent electrical transport data. The resistivity (ρ–T) profile suggests the presence of magnetic polarons, indicative of strong coupling between charge carriers and local magnetic moments. At low temperatures (<em>T</em> < 40 K), magnetoresistance (MR) measurements exhibit hysteresis as a function of magnetic field, pointing to the coexistence of ferromagnetic and antiferromagnetic phases. With increasing temperature, negative MR becomes prominent above the magnetic ordering point due to polaron formation. To gain deeper insight into the electronic structure, density functional theory (DFT) calculations were performed. These reveal a competition between ferromagnetic and antiferromagnetic interactions, underscoring the complex magnetic landscape of MnSb<sub>2</sub>Te<sub>4</sub>. Overall, our findings highlight MnSb<sub>2</sub>Te<sub>4</sub> as a compelling system that hosts coexisting magnetic phases intertwined with topological characteristics, warranting further exploration of its magneto-topological coupling.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173696"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578496","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 : 2025-11-20DOI: 10.1016/j.jmmm.2025.173693
R. Preyadarshini , S. Kavita , A. Kumar , D. Sivaprahasam
This study investigates the effects of Sb, Ge, and Ga doping in AlFe2B2 on magnetic and magneto-caloric properties. Samples of AlFe2B2 and AlFe1.9M0.1B2 (M = Ge, Ga and Sb) with 20% excess Al were synthesized by arc melting, and the powders processed were investigated for their phase constituents, microstructure, magnetic properties and magneto-caloric effect. The parent compounds prepared showed the AlFe2B2 phase with a FeB secondary phase. However, in Sb and Ga-doped samples, an additional impurity phase, Al13Fe4, was observed apart from FeB, while in Ge-doped, only the AlB2 impurity phase was present. The Curie temperature of AlFe2B2 is 277 K, increasing with Sb, Ge, and Ga doping to 287 K, 297 K, and 296 K, respectively. The magnetization (M) is also higher with Ge and Ga addition in the 100-300 K range; however, with Sb doping, the M decreases significantly compared to parent AlFe2B2. The magnetic entropy change under 2 T reached 2.31 JKg−1 K−1 near 274 K in AlFe2B2, which decreases to 2.55 JKg−1 K−1 and 1.92 JKg−1 K−1 with Ge and Ga, respectively. With Sb doping, the MC change was affected dramatically to 0.31 JKg−1 K−1. However, the relative cooling power of Ge doped is the same as that of parent AlFe2B2. This research advances the understanding of the relationship between doping elements and magnetic properties in AlFe2B2 and opens pathways for designing magneto-caloric materials with tailored magnetic characteristics.
{"title":"Magnetocaloric properties of Sb, Ge, and Ga doped AlFe2B2","authors":"R. Preyadarshini , S. Kavita , A. Kumar , D. Sivaprahasam","doi":"10.1016/j.jmmm.2025.173693","DOIUrl":"10.1016/j.jmmm.2025.173693","url":null,"abstract":"<div><div>This study investigates the effects of Sb, Ge, and Ga doping in AlFe<sub>2</sub>B<sub>2</sub> on magnetic and magneto-caloric properties. Samples of AlFe<sub>2</sub>B<sub>2</sub> and AlFe<sub>1.9</sub>M<sub>0.1</sub>B<sub>2</sub> (M = Ge, Ga and Sb) with 20% excess Al were synthesized by arc melting, and the powders processed were investigated for their phase constituents, microstructure, magnetic properties and magneto-caloric effect. The parent compounds prepared showed the AlFe<sub>2</sub>B<sub>2</sub> phase with a FeB secondary phase. However, in Sb and Ga-doped samples, an additional impurity phase, Al<sub>13</sub>Fe<sub>4</sub>, was observed apart from FeB, while in Ge-doped, only the AlB<sub>2</sub> impurity phase was present. The Curie temperature of AlFe<sub>2</sub>B<sub>2</sub> is 277 K, increasing with Sb, Ge, and Ga doping to 287 K, 297 K, and 296 K, respectively. The magnetization (M) is also higher with Ge and Ga addition in the 100-300 K range; however, with Sb doping, the M decreases significantly compared to parent AlFe<sub>2</sub>B<sub>2</sub>. The magnetic entropy change under 2 T reached 2.31 JKg<sup>−1</sup> K<sup>−1</sup> near 274 K in AlFe<sub>2</sub>B<sub>2</sub>, which decreases to 2.55 JKg<sup>−1</sup> K<sup>−1</sup> and 1.92 JKg<sup>−1</sup> K<sup>−1</sup> with Ge and Ga, respectively. With Sb doping, the MC change was affected dramatically to 0.31 JKg<sup>−1</sup> K<sup>−1</sup>. However, the relative cooling power of Ge doped is the same as that of parent AlFe<sub>2</sub>B<sub>2</sub>. This research advances the understanding of the relationship between doping elements and magnetic properties in AlFe<sub>2</sub>B<sub>2</sub> and opens pathways for designing magneto-caloric materials with tailored magnetic characteristics.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173693"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578493","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 : 2025-11-20DOI: 10.1016/j.jmmm.2025.173689
Ai-Ling Ma , Jun-Kang Jiang , Cui-E Hu , Hua-Yun Geng , Xiang-Rong Chen
Two-dimensional (2D) ferrovalley materials, characterized by spontaneous spin and valley polarizations, have garnered considerable research interest due to their promising applications in spintronics. In this work, using first-principles calculations and Monte Carlo simulations, we demonstrate that the Janus YClBr monolayer is a ferrovalley semiconductor with a high Curie temperature and intrinsic valley polarization. Carrier doping can induce a semiconductor-to-half-metal transition, achieving 100 % spin polarization. The intrinsic Curie temperature reaches 252 K and can be enhanced to 457 K when hole doping reaches 6.37 × 1013 cm−2 (0.08 holes per atom), surpassing the room-temperature threshold. Even minimal doping triggers a reversible transition of the easy magnetization axis from in-plane to out-of-plane. With out-of-plane mirror symmetry broken, we explored the variations in layer charge under an external electric field. Moreover, the interplay between external and built-in electric fields imparts a distinctive charge transfer behavior to this layer. The coercive force derived from the hysteresis loop is 0.02 T, with minimal hysteresis loss, indicating its high responsiveness to external magnetic fields. These properties make this material an excellent candidate for room-temperature spintronic devices.
{"title":"Electronic structures and magnetic properties of Janus YClBr monolayer controlled by carrier doping","authors":"Ai-Ling Ma , Jun-Kang Jiang , Cui-E Hu , Hua-Yun Geng , Xiang-Rong Chen","doi":"10.1016/j.jmmm.2025.173689","DOIUrl":"10.1016/j.jmmm.2025.173689","url":null,"abstract":"<div><div>Two-dimensional (2D) ferrovalley materials, characterized by spontaneous spin and valley polarizations, have garnered considerable research interest due to their promising applications in spintronics. In this work, using first-principles calculations and Monte Carlo simulations, we demonstrate that the Janus YClBr monolayer is a ferrovalley semiconductor with a high Curie temperature and intrinsic valley polarization. Carrier doping can induce a semiconductor-to-half-metal transition, achieving 100 % spin polarization. The intrinsic Curie temperature reaches 252 K and can be enhanced to 457 K when hole doping reaches 6.37 × 10<sup>13</sup> cm<sup>−2</sup> (0.08 holes per atom), surpassing the room-temperature threshold. Even minimal doping triggers a reversible transition of the easy magnetization axis from in-plane to out-of-plane. With out-of-plane mirror symmetry broken, we explored the variations in layer charge under an external electric field. Moreover, the interplay between external and built-in electric fields imparts a distinctive charge transfer behavior to this layer. The coercive force derived from the hysteresis loop is 0.02 T, with minimal hysteresis loss, indicating its high responsiveness to external magnetic fields. These properties make this material an excellent candidate for room-temperature spintronic devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173689"},"PeriodicalIF":3.0,"publicationDate":"2025-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145621894","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 : 2025-11-19DOI: 10.1016/j.jmmm.2025.173688
H. Zaari , G. Dimitri Ngantso , H. Bouhani , A. El Kenz , A. Benyoussef
Understanding the interplay between magnetic and elastic properties in magnetostrictive materials is crucial for advancing technological applications such as sensors, actuators, and energy harvesting devices. TbFe₂, a rare-earth-based magnetostrictive compound, exhibits complex magnetoelastic coupling that remains partially unexplored. In this study, we investigate the electronic, elastic, and magnetoelastic properties of using density functional theory (DFT) within the generalized gradient approximation (GGA). We analyze the total and partial densities of states (DOS), determine elastic and magnetoelastic constants, and examine the effects of strain on the electronic and magnetic properties. Our findings reveal that Tb atoms play a dominant role in the compound's magnetism, with strain significantly influencing the magnetocrystalline anisotropy and magnetic moments. The calculated elastic and magnetoelastic constants confirm the structural stability of and highlight its strong magnetostrictive response. These results provide valuable insights into the fundamental mechanisms governing magnetoelasticity in , paving the way for its integration into advanced functional devices.
{"title":"Magnetoelastic response and strain-controlled magnetic order in TbFe₂: A first-principles study","authors":"H. Zaari , G. Dimitri Ngantso , H. Bouhani , A. El Kenz , A. Benyoussef","doi":"10.1016/j.jmmm.2025.173688","DOIUrl":"10.1016/j.jmmm.2025.173688","url":null,"abstract":"<div><div>Understanding the interplay between magnetic and elastic properties in magnetostrictive materials is crucial for advancing technological applications such as sensors, actuators, and energy harvesting devices. TbFe₂, a rare-earth-based magnetostrictive compound, exhibits complex magnetoelastic coupling that remains partially unexplored. In this study, we investigate the electronic, elastic, and magnetoelastic properties of <span><math><msub><mi>TbFe</mi><mn>2</mn></msub></math></span> using density functional theory (DFT) within the generalized gradient approximation (GGA). We analyze the total and partial densities of states (DOS), determine elastic and magnetoelastic constants, and examine the effects of strain on the electronic and magnetic properties. Our findings reveal that Tb atoms play a dominant role in the compound's magnetism, with strain significantly influencing the magnetocrystalline anisotropy and magnetic moments. The calculated elastic and magnetoelastic constants confirm the structural stability of <span><math><msub><mi>TbFe</mi><mn>2</mn></msub></math></span> and highlight its strong magnetostrictive response. These results provide valuable insights into the fundamental mechanisms governing magnetoelasticity in <span><math><msub><mi>TbFe</mi><mn>2</mn></msub></math></span>, paving the way for its integration into advanced functional devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173688"},"PeriodicalIF":3.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578492","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 : 2025-11-19DOI: 10.1016/j.jmmm.2025.173690
Kai-Wen Wu , Chuan-Xiao Peng , Zi-Long Wang , Yang Luo , Ning-Tao Quan , Jian-Hui Dong , Xiao-Feng Ji , Yuan-Fei Yang , Qin-Jia Wang , Yue Wang
To enhance the coercivity of hot-deformed magnets via grain boundary diffusion (GBD) while mitigating the detrimental impacts of grain orientation degradation and associated remanence loss, this study proposes a two-stage strategy. Initially, a ternary Pr80Ga10Cu10 (at.%) diffusion source was utilized for GBD to elevate coercivity. Subsequently, a secondary hot deformation (SHD) process was implemented to optimize the crystallographic texture, thereby improving remanence. This approach successfully fabricated a hot-deformed magnet with outstanding comprehensive magnetic properties: a coercivity of 2.23 T, a remanence of 1.31 T, and a maximum energy product ((BH)max) of 327.95 kJ/m3. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed that SHD process effectively optimized the texture of hot-deformed magnets, thereby contributing to an improvement in remanence. Notably, although the width of the grain boundary phase decreased after SHD treatment, the distribution of rare-earth (RE) elements at the grain boundaries became more homogeneous. Furthermore, the presence of the Nd6Fe13Ga phase was identified at the triple junctions. This phase formation reduced the concentration of ferromagnetic phases at the grain boundaries, weakened the intergranular exchange coupling, and consequently maintained the high coercivity of the magnet.
{"title":"Secondary hot deformation to improve the magnetic performance of Pr80Ga10Cu10 grain boundary diffused hot-deformed NdFeB magnets","authors":"Kai-Wen Wu , Chuan-Xiao Peng , Zi-Long Wang , Yang Luo , Ning-Tao Quan , Jian-Hui Dong , Xiao-Feng Ji , Yuan-Fei Yang , Qin-Jia Wang , Yue Wang","doi":"10.1016/j.jmmm.2025.173690","DOIUrl":"10.1016/j.jmmm.2025.173690","url":null,"abstract":"<div><div>To enhance the coercivity of hot-deformed magnets via grain boundary diffusion (GBD) while mitigating the detrimental impacts of grain orientation degradation and associated remanence loss, this study proposes a two-stage strategy. Initially, a ternary Pr<sub>80</sub>Ga<sub>10</sub>Cu<sub>10</sub> (at.%) diffusion source was utilized for GBD to elevate coercivity. Subsequently, a secondary hot deformation (SHD) process was implemented to optimize the crystallographic texture, thereby improving remanence. This approach successfully fabricated a hot-deformed magnet with outstanding comprehensive magnetic properties: a coercivity of 2.23 T, a remanence of 1.31 T, and a maximum energy product ((<em>BH</em>)<sub>max</sub>) of 327.95 kJ/m<sup>3</sup>. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses revealed that SHD process effectively optimized the texture of hot-deformed magnets, thereby contributing to an improvement in remanence. Notably, although the width of the grain boundary phase decreased after SHD treatment, the distribution of rare-earth (RE) elements at the grain boundaries became more homogeneous. Furthermore, the presence of the Nd<sub>6</sub>Fe<sub>13</sub>Ga phase was identified at the triple junctions. This phase formation reduced the concentration of ferromagnetic phases at the grain boundaries, weakened the intergranular exchange coupling, and consequently maintained the high coercivity of the magnet.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173690"},"PeriodicalIF":3.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145600643","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 : 2025-11-19DOI: 10.1016/j.jmmm.2025.173691
Ilya V. Kashin , Alexander S. Iakovlev , Sergei N. Andreev
In this study we present a theoretical investigation of the role that ferromagnetic plane (111) plays in the formation of magnetocrystalline anisotropy (MCA) effects in CoO and FeO monoxides. For this purpose, a first-principles calculations of the electronic structure are performed within the GGA approach. Based on the low-energy model in the Wannier functions basis, the MCA energy angular profile and the isotropic exchange environment of the transition metal atom are estimated using -dependent Green’s functions. We have revealed a clear regularity in the direction of the easy and hard axes in both systems as lying in the (111) plane or along [111]. While for CoO the easy/hard axis orientation is (111)/[111], for FeO it appears reversed and thus emphasizes the fundamental importance of (111) as the geometrical driver of the magnetism in the crystals. The identification of the contributions that individual sublattices make to the MCA energy allowed us to reveal the decisive role of the electron hopping mechanisms in easy axis orientation. Considering the MCA and exchange environment with orbital decomposition in CoO and FeO under homogeneous strain in the (111) plane and along [111] showed a direct interrelation between the ferro- and antiferromagnetic contributions to the exchange environment and the energetic stability of the easy axis.
{"title":"How ferromagnetic plane drives magnetocrystalline anisotropy in antiferromagnetic CoO and FeO","authors":"Ilya V. Kashin , Alexander S. Iakovlev , Sergei N. Andreev","doi":"10.1016/j.jmmm.2025.173691","DOIUrl":"10.1016/j.jmmm.2025.173691","url":null,"abstract":"<div><div>In this study we present a theoretical investigation of the role that ferromagnetic plane (111) plays in the formation of magnetocrystalline anisotropy (MCA) effects in CoO and FeO monoxides. For this purpose, a first-principles calculations of the electronic structure are performed within the GGA<span><math><mrow><mo>+</mo><mi>U</mi></mrow></math></span> approach. Based on the low-energy model in the Wannier functions basis, the MCA energy angular profile and the isotropic exchange environment of the transition metal atom are estimated using <span><math><mi>k</mi></math></span>-dependent Green’s functions. We have revealed a clear regularity in the direction of the easy and hard axes in both systems as lying in the (111) plane or along [111]. While for CoO the easy/hard axis orientation is (111)/[111], for FeO it appears reversed and thus emphasizes the fundamental importance of (111) as the geometrical driver of the magnetism in the crystals. The identification of the contributions that individual sublattices make to the MCA energy allowed us to reveal the decisive role of the electron hopping mechanisms in easy axis orientation. Considering the MCA and exchange environment with orbital decomposition in CoO and FeO under homogeneous strain in the (111) plane and along [111] showed a direct interrelation between the ferro- and antiferromagnetic contributions to the exchange environment and the energetic stability of the easy axis.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173691"},"PeriodicalIF":3.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578494","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 : 2025-11-19DOI: 10.1016/j.jmmm.2025.173686
Christopher C. Tisdell
Recently, Kezzer et al. (2023) analyzed a two-point boundary value problem arising from the velocity field of a MHD hybrid nanofluid flow. There are several anomolies in their work that I would like to correct.
{"title":"Letter to the Editor: Velocity-slip boundary conditions and shape factor effects on MHD hybrid nanofluid flow via converging/diverging channels","authors":"Christopher C. Tisdell","doi":"10.1016/j.jmmm.2025.173686","DOIUrl":"10.1016/j.jmmm.2025.173686","url":null,"abstract":"<div><div>Recently, Kezzer et al. (2023) analyzed a two-point boundary value problem arising from the velocity field of a MHD hybrid nanofluid flow. There are several anomolies in their work that I would like to correct.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"637 ","pages":"Article 173686"},"PeriodicalIF":3.0,"publicationDate":"2025-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145578495","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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