Pub Date : 2025-04-14DOI: 10.1109/LMAG.2025.3560867
Karthik G;Shipra Das;T. R. Naveen Kumar;K Ravichandran
Engineered Heusler alloys have potential applications in spintronic devices owing to their fascinating properties. Therefore, we synthesized a ternary Cr2MnGe Heusler alloy using a simple solid-state reaction. Rietveld refinement of the X-ray diffraction data confirmed the presence of a cubic Fd-3m structure, specifically the B32a disorder Heusler phase with a space group number of 227. The microstructure and chemical composition of the Cr2MnGe sample confirmed agglomeration and adherence to the nominal composition of the Heusler alloy. Furthermore, the Cr2MnGe sample exhibits antiferromagnetic behavior with ferromagnetic clusters due to the site swapping of Cr–Mn and Cr–Ge, which contributes to a magnetic signal in the zero-field-cooled and field-cooled measurements. These findings highlight the potential of Cr2MnGe for application in magnetic tunnel junctions and spin valves, contributing to advancements in spintronic technologies.
{"title":"Study of Structural and Magnetic Properties of Antiferromagnetic Cr2MnGe Heusler Alloy","authors":"Karthik G;Shipra Das;T. R. Naveen Kumar;K Ravichandran","doi":"10.1109/LMAG.2025.3560867","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3560867","url":null,"abstract":"Engineered Heusler alloys have potential applications in spintronic devices owing to their fascinating properties. Therefore, we synthesized a ternary Cr<sub>2</sub>MnGe Heusler alloy using a simple solid-state reaction. Rietveld refinement of the X-ray diffraction data confirmed the presence of a cubic Fd-3m structure, specifically the B32a disorder Heusler phase with a space group number of 227. The microstructure and chemical composition of the Cr<sub>2</sub>MnGe sample confirmed agglomeration and adherence to the nominal composition of the Heusler alloy. Furthermore, the Cr<sub>2</sub>MnGe sample exhibits antiferromagnetic behavior with ferromagnetic clusters due to the site swapping of Cr–Mn and Cr–Ge, which contributes to a magnetic signal in the zero-field-cooled and field-cooled measurements. These findings highlight the potential of Cr<sub>2</sub>MnGe for application in magnetic tunnel junctions and spin valves, contributing to advancements in spintronic technologies.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-4"},"PeriodicalIF":1.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144232180","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-14DOI: 10.1109/LMAG.2025.3560858
Vadym Zayets
This letter systematically investigates the fundamental mechanisms driving the voltage-controlled magnetic anisotropy (VCMA) effect, with a focus on the dependencies of the anisotropy field and the strength of spin-orbit (SO) interaction on gate voltage, measured in Ta/FeB/MgO nanomagnets. Our findings reveal an intriguing opposite polarity in the gate-voltage dependencies of the anisotropy field and the coefficient of SO interaction across all studied nanomagnets. This discovery challenges the prevailing assumption that SO interaction is the primary contributor to the VCMA effect, instead suggesting that gate-voltage modulation of magnetization is likely the dominant factor, as its polarity aligns with the observed modulation of anisotropy. The modulation of magnetic anisotropy is governed by two major contributions with opposite polarities, which tend to counterbalance each other, reducing the overall VCMA effect. Optimizing this balance could significantly enhance the VCMA effect, offering a promising avenue for broadening its applications. In addition, our measurements confirm that gate voltage does not modulate the in-plane component of spin accumulation, providing further insights into the underlying mechanisms of the VCMA effect.
{"title":"Features and Peculiarities of Gate-Voltage Modulation of Spin-Orbit Interaction in FeB Nanomagnets: Insights Into the Physical Origins of the Voltage-Controlled Magnetic Anisotropy Effect","authors":"Vadym Zayets","doi":"10.1109/LMAG.2025.3560858","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3560858","url":null,"abstract":"This letter systematically investigates the fundamental mechanisms driving the voltage-controlled magnetic anisotropy (VCMA) effect, with a focus on the dependencies of the anisotropy field and the strength of spin-orbit (SO) interaction on gate voltage, measured in Ta/FeB/MgO nanomagnets. Our findings reveal an intriguing opposite polarity in the gate-voltage dependencies of the anisotropy field and the coefficient of SO interaction across all studied nanomagnets. This discovery challenges the prevailing assumption that SO interaction is the primary contributor to the VCMA effect, instead suggesting that gate-voltage modulation of magnetization is likely the dominant factor, as its polarity aligns with the observed modulation of anisotropy. The modulation of magnetic anisotropy is governed by two major contributions with opposite polarities, which tend to counterbalance each other, reducing the overall VCMA effect. Optimizing this balance could significantly enhance the VCMA effect, offering a promising avenue for broadening its applications. In addition, our measurements confirm that gate voltage does not modulate the in-plane component of spin accumulation, providing further insights into the underlying mechanisms of the VCMA effect.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-4"},"PeriodicalIF":1.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144108338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-14DOI: 10.1109/LMAG.2025.3560889
Goran Mihajlović;Wonjoon Jung;Noraica Dávila;Jeffrey Lille;Michael Tran;Jordan A. Katine;Michael K. Grobis
We present an experimental study of the size-dependent tunneling magnetoresistance ratio (TMR) and voltage read signal in perpendicular spin transfer torque magnetoresistive random-access (MRAM) memory cells, which shows that the maximum read signal is mostly independent of the size, while TMR decreases with decreasing size. Our analysis shows that this is due to a size-dependent parasitic resistance specific to the nanofabrication process and that the intrinsic $Delta text{RA}$ of the cells is size-independent. As a consequence, we show that the electrical diameter of an MRAM cell can be reliably extracted down to sub-20 nm assuming that $Delta text{RA}$ does not depend on the cell size.
{"title":"Size Dependence of the Read Voltage and Electrical Diameter of STT MRAM Cells","authors":"Goran Mihajlović;Wonjoon Jung;Noraica Dávila;Jeffrey Lille;Michael Tran;Jordan A. Katine;Michael K. Grobis","doi":"10.1109/LMAG.2025.3560889","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3560889","url":null,"abstract":"We present an experimental study of the size-dependent tunneling magnetoresistance ratio (TMR) and voltage read signal in perpendicular spin transfer torque magnetoresistive random-access (MRAM) memory cells, which shows that the maximum read signal is mostly independent of the size, while TMR decreases with decreasing size. Our analysis shows that this is due to a size-dependent parasitic resistance specific to the nanofabrication process and that the intrinsic <inline-formula><tex-math>$Delta text{RA}$</tex-math></inline-formula> of the cells is size-independent. As a consequence, we show that the electrical diameter of an MRAM cell can be reliably extracted down to sub-20 nm assuming that <inline-formula><tex-math>$Delta text{RA}$</tex-math></inline-formula> does not depend on the cell size.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144072775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-04-14DOI: 10.1109/LMAG.2025.3560886
Yoshiaki Adachi;Daisuke Oyama;Gen Uehara
Acquiring position, orientation, and sensitivity of magnetometers in a helmet-shaped sensor array is crucial for accurate current source reconstruction in magnetoencephalography. To determine these parameters for each magnetometer, we utilize a spherical calibration coil array. In our previous study, the position and orientation of each magnetometer were determined as the solution of an inverse problem through a numerical search that minimized the difference between the theoretical magnetic field signals from each coil and the measured signals detected by the magnetometer. In this study, we applied a deep neural network to estimate the position and orientation of each magnetometer in the helmet-shaped sensor array without solving the inverse problem. A total of 223 million pairs of a given magnetometer's five parameters (x, y, z, θ, and ϕ) and the corresponding theoretical magnetic field signals from the coils were used to train the neural network. The training process required approximately 53 h using a commercially available GPU-equipped computer. The trained neural network was then applied to acquire the sensor geometry from magnetic field data obtained during a conventional calibration procedure for a 160-channel whole-head magnetoencephalograph system using a spherical calibration coil array. The position and orientation of each magnetometer estimated by this method deviated by an average of 0.65 mm and 0.51°, respectively, from those obtained via the conventional inverse problem approach. The acquisition of the geometry for all 160 magnetometers required less than 8 ms. With such high-speed acquisition, this approach opens possibilities for future applications in acquiring positional information of wearable sensor arrays whose structures change in real time.
获取头盔形传感器阵列中磁强计的位置、方向和灵敏度对于脑磁图中电流源的精确重建至关重要。为了确定每个磁强计的这些参数，我们使用球形校准线圈阵列。在我们之前的研究中，每个磁力计的位置和方向都是通过数值搜索来确定的，通过数值搜索来最小化每个线圈的理论磁场信号与磁力计检测到的测量信号之间的差异。在这项研究中，我们应用深度神经网络来估计头盔形传感器阵列中每个磁强计的位置和方向，而不解决逆问题。给定磁力计的五个参数（x, y, z， θ和ϕ）和线圈中相应的理论磁场信号共2.23亿对用于训练神经网络。训练过程需要大约53小时使用市售的gpu配备的计算机。然后应用训练好的神经网络从常规校准过程中获得的磁场数据中获取传感器几何形状，该过程使用球形校准线圈阵列对160通道全头脑磁仪系统进行校准。用该方法估计的每个磁强计的位置和方向与传统的反问题方法分别平均偏差0.65 mm和0.51°。所有160个磁力计的几何形状的采集需要不到8毫秒。通过这种高速采集，该方法为获取结构实时变化的可穿戴传感器阵列的位置信息开辟了未来应用的可能性。
{"title":"Fast Acquisition of Sensor Array Geometry of Whole-Head Magnetoencephalograph Systems Using a Neural Network","authors":"Yoshiaki Adachi;Daisuke Oyama;Gen Uehara","doi":"10.1109/LMAG.2025.3560886","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3560886","url":null,"abstract":"Acquiring position, orientation, and sensitivity of magnetometers in a helmet-shaped sensor array is crucial for accurate current source reconstruction in magnetoencephalography. To determine these parameters for each magnetometer, we utilize a spherical calibration coil array. In our previous study, the position and orientation of each magnetometer were determined as the solution of an inverse problem through a numerical search that minimized the difference between the theoretical magnetic field signals from each coil and the measured signals detected by the magnetometer. In this study, we applied a deep neural network to estimate the position and orientation of each magnetometer in the helmet-shaped sensor array without solving the inverse problem. A total of 223 million pairs of a given magnetometer's five parameters (<italic>x</i>, <italic>y</i>, <italic>z</i>, <italic>θ</i>, and <italic>ϕ</i>) and the corresponding theoretical magnetic field signals from the coils were used to train the neural network. The training process required approximately 53 h using a commercially available GPU-equipped computer. The trained neural network was then applied to acquire the sensor geometry from magnetic field data obtained during a conventional calibration procedure for a 160-channel whole-head magnetoencephalograph system using a spherical calibration coil array. The position and orientation of each magnetometer estimated by this method deviated by an average of 0.65 mm and 0.51°, respectively, from those obtained via the conventional inverse problem approach. The acquisition of the geometry for all 160 magnetometers required less than 8 ms. With such high-speed acquisition, this approach opens possibilities for future applications in acquiring positional information of wearable sensor arrays whose structures change in real time.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10964712","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144179108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-28DOI: 10.1109/LMAG.2025.3555942
Linrong Yao;Hongchao Xie;Bin Hu;Sheng Jiang
Spin Hall nano-oscillators (SHNOs) have garnered attention due to their broad application prospects in microwave generators, information storage, and artificial intelligence computing. This has necessitated the development of efficient methods to control the magneto-dynamics of SHNOs. Magnetic field control requires a field generator, and current control suffers from a narrow frequency range and low efficiency. We present an approach to efficiently control the SHNO magneto-dynamics, i.e., a piezoelectric-based SHNO system, to achieve voltage-modulated magneto-dynamics through magneto-electric coupling. Through micromagnetic simulations, this work demonstrates the indirect control of the magneto-dynamics by voltage-modulated magnetic anisotropy, revealing the impact of changes in magnetic anisotropy on the magneto-dynamics and the underlying physical mechanisms. This discovery enhances the degree of freedom for electrical modulation of SHNOs and contributes to developing advanced spintronic devices.
{"title":"Voltage-Modulated Magneto-Dynamics in Spin Hall Nano-Oscillators","authors":"Linrong Yao;Hongchao Xie;Bin Hu;Sheng Jiang","doi":"10.1109/LMAG.2025.3555942","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3555942","url":null,"abstract":"Spin Hall nano-oscillators (SHNOs) have garnered attention due to their broad application prospects in microwave generators, information storage, and artificial intelligence computing. This has necessitated the development of efficient methods to control the magneto-dynamics of SHNOs. Magnetic field control requires a field generator, and current control suffers from a narrow frequency range and low efficiency. We present an approach to efficiently control the SHNO magneto-dynamics, i.e., a piezoelectric-based SHNO system, to achieve voltage-modulated magneto-dynamics through magneto-electric coupling. Through micromagnetic simulations, this work demonstrates the indirect control of the magneto-dynamics by voltage-modulated magnetic anisotropy, revealing the impact of changes in magnetic anisotropy on the magneto-dynamics and the underlying physical mechanisms. This discovery enhances the degree of freedom for electrical modulation of SHNOs and contributes to developing advanced spintronic devices.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143908431","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-17DOI: 10.1109/LMAG.2025.3551990
Noura Zenbaa;Khrystyna O. Levchenko;Jaganandha Panda;Kristýna Davídková;Moritz Ruhwedel;Sebastian Knauer;Morris Lindner;Carsten Dubs;Qi Wang;Michal Urbánek;Philipp Pirro;Andrii V. Chumak
We demonstrate a magnonic isolator based on a bilayer structure of yttrium iron garnet (YIG) and cobalt iron boron (CoFeB). The bilayer exhibits pronounced nonreciprocal spin-wave propagation, enabled by dipolar coupling and the magnetic properties of the two layers. The YIG layer provides low damping and efficient spin-wave propagation, whereas the CoFeB layer introduces strong magnetic anisotropy, critical for achieving the isolator functionality. Experimental results, supported by numerical simulations, show unidirectional propagation of magneto-static surface spin waves, significantly suppressing backscattered waves. This behavior was confirmed through wavevector-resolved and microfocused Brillouin light scattering measurements and is supported by numerical simulations. The developed YIG/SiO$_{2}$/CoFeB bilayer magnonic isolator demonstrates the feasibility of leveraging nonreciprocal spin-wave dynamics for functional magnonic devices, paving the way for energy-efficient, wave-based signal processing technologies.
{"title":"YIG/CoFeB Bilayer Magnonic Isolator","authors":"Noura Zenbaa;Khrystyna O. Levchenko;Jaganandha Panda;Kristýna Davídková;Moritz Ruhwedel;Sebastian Knauer;Morris Lindner;Carsten Dubs;Qi Wang;Michal Urbánek;Philipp Pirro;Andrii V. Chumak","doi":"10.1109/LMAG.2025.3551990","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3551990","url":null,"abstract":"We demonstrate a magnonic isolator based on a bilayer structure of yttrium iron garnet (YIG) and cobalt iron boron (CoFeB). The bilayer exhibits pronounced nonreciprocal spin-wave propagation, enabled by dipolar coupling and the magnetic properties of the two layers. The YIG layer provides low damping and efficient spin-wave propagation, whereas the CoFeB layer introduces strong magnetic anisotropy, critical for achieving the isolator functionality. Experimental results, supported by numerical simulations, show unidirectional propagation of magneto-static surface spin waves, significantly suppressing backscattered waves. This behavior was confirmed through wavevector-resolved and microfocused Brillouin light scattering measurements and is supported by numerical simulations. The developed YIG/SiO<inline-formula><tex-math>$_{2}$</tex-math></inline-formula>/CoFeB bilayer magnonic isolator demonstrates the feasibility of leveraging nonreciprocal spin-wave dynamics for functional magnonic devices, paving the way for energy-efficient, wave-based signal processing technologies.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10930529","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143865306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-14DOI: 10.1109/LMAG.2025.3551243
Gabriel M. Vieira;Marcelo A. Rosa;Paulo A. P. Wendhausen;Maximiliano D. Martins
Fused deposition modeling (FDM) is an additive manufacturing technique that has become widely used in many fields of engineering and has recently proven to be suitable for producing complex, net-shaped bonded Nd–Fe–B magnets. At the same time, recycling end-of-life magnets has been an emerging concern due to their increasing presence in current technologies and the intrinsic scarcity of rare-Earth elements, such as neodymium and praseodymium. Here, we investigated the feasibility of using recycled nanocrystalline Nd–Fe–B powders, obtained from a hydrogenation–disproportionation–desorption–recombination (HDDR) process in the preparation of FDM feedstock and subsequent printing of magnetic parts. Recycled magnetic powder was mixed with polylactic acid and extruded into filaments containing increasing volume fractions of magnetic powder. It was possible to obtain filaments containing from 6.7% to 23.6% in volume (30.4 to 65.2 wt.%) of the magnetic powder, from which parts could be printed, reaching maximum coercivity (Hcj) of 707.7 ± 3.5 kA/m, maximum remanence (Br) of 84.5 ± 0.4 mT, maximum energy product (BHmax) of 1.3 kJ/m3, and average part porosity of 42 ± 8%. Coercivity loss of about 8.6% was observed in the printed parts compared to the recycled powder (750±75 kA/m). Aging experiments showed that such loss may be a combined effect of thermal and oxidation effects of the magnetic particles during the additive manufacturing processing. The present work has demonstrated the achievement of ready-to-use, high-coercivity FDM filaments, and 3-D-printed parts using recycled Nd–Fe–B HDDR powders.
{"title":"Ready-to-Use Composite Fused Deposition Modeling Filaments Produced With Polylactic Acid and Recycled Nd–Fe–B Nanocrystalline Powder for Additive Manufacturing of Bonded Magnets","authors":"Gabriel M. Vieira;Marcelo A. Rosa;Paulo A. P. Wendhausen;Maximiliano D. Martins","doi":"10.1109/LMAG.2025.3551243","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3551243","url":null,"abstract":"Fused deposition modeling (FDM) is an additive manufacturing technique that has become widely used in many fields of engineering and has recently proven to be suitable for producing complex, net-shaped bonded Nd–Fe–B magnets. At the same time, recycling end-of-life magnets has been an emerging concern due to their increasing presence in current technologies and the intrinsic scarcity of rare-Earth elements, such as neodymium and praseodymium. Here, we investigated the feasibility of using recycled nanocrystalline Nd–Fe–B powders, obtained from a hydrogenation–disproportionation–desorption–recombination (HDDR) process in the preparation of FDM feedstock and subsequent printing of magnetic parts. Recycled magnetic powder was mixed with polylactic acid and extruded into filaments containing increasing volume fractions of magnetic powder. It was possible to obtain filaments containing from 6.7% to 23.6% in volume (30.4 to 65.2 wt.%) of the magnetic powder, from which parts could be printed, reaching maximum coercivity (<italic>H</i><sub>cj</sub>) of 707.7 ± 3.5 kA/m, maximum remanence (<italic>B</i><sub>r</sub>) of 84.5 ± 0.4 mT, maximum energy product (<italic>BH</i><sub>max</sub>) of 1.3 kJ/m<sup>3</sup>, and average part porosity of 42 ± 8%. Coercivity loss of about 8.6% was observed in the printed parts compared to the recycled powder (750±75 kA/m). Aging experiments showed that such loss may be a combined effect of thermal and oxidation effects of the magnetic particles during the additive manufacturing processing. The present work has demonstrated the achievement of ready-to-use, high-coercivity FDM filaments, and 3-D-printed parts using recycled Nd–Fe–B HDDR powders.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143856196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-14DOI: 10.1109/LMAG.2025.3551266
Aakansha Aakansha;Seenipandian Ravi
This letter covers the structural and magnetic properties of lanthanum-substituted gadolinium iron garnet (GIG) (Gd3-xLaxFe5O12), where the La ion was substituted at the Gd site. X-ray diffraction analysis suggested that the synthesized samples possess cubic crystal structure with an increase in lattice constant with La substitution. The crystallite size was estimated through the Williamson–Hall plot analysis and found to increase from 50.577 for ${x}$ = 0 to 67.343 nm for ${x}$ = 0.4. The room temperature magnetization value was increasing from 0.162 to 2.536 emu/g from pure to La-substituted GIG. These materials display a ferrimagnetic to paramagnetic phase transition as high temperature rose from 565 to 573 K, which is attributed to the high superexchange interaction between Fe3+ ions. In addition to transition, temperature magnetic compensation was also observed below room temperature. The coercivity of the samples was estimated from the room temperature hysteresis curve, which shows soft ferrimagnetic behavior. The stable crystal structure, low magnetic compensation, low coercive field, and high transition temperature make these materials suitable for communication devices.
{"title":"Tuning Magnetic Behavior of Lanthanum-Substituted Gd3Fe5O12: An Experimental Study","authors":"Aakansha Aakansha;Seenipandian Ravi","doi":"10.1109/LMAG.2025.3551266","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3551266","url":null,"abstract":"This letter covers the structural and magnetic properties of lanthanum-substituted gadolinium iron garnet (GIG) (Gd<sub>3-</sub><italic><sub>x</sub></i>La<italic><sub>x</sub></i>Fe<sub>5</sub>O<sub>12</sub>), where the La ion was substituted at the Gd site. X-ray diffraction analysis suggested that the synthesized samples possess cubic crystal structure with an increase in lattice constant with La substitution. The crystallite size was estimated through the Williamson–Hall plot analysis and found to increase from 50.577 for <inline-formula><tex-math>${x}$</tex-math></inline-formula> = 0 to 67.343 nm for <inline-formula><tex-math>${x}$</tex-math></inline-formula> = 0.4. The room temperature magnetization value was increasing from 0.162 to 2.536 emu/g from pure to La-substituted GIG. These materials display a ferrimagnetic to paramagnetic phase transition as high temperature rose from 565 to 573 K, which is attributed to the high superexchange interaction between Fe<sup>3+</sup> ions. In addition to transition, temperature magnetic compensation was also observed below room temperature. The coercivity of the samples was estimated from the room temperature hysteresis curve, which shows soft ferrimagnetic behavior. The stable crystal structure, low magnetic compensation, low coercive field, and high transition temperature make these materials suitable for communication devices.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143830542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1109/LMAG.2025.3541915
Yixiao Ding;Xuan Wang;Mark G. Allen
Quasi-static magnetic fields can be used to modulate the magnetic and electrical properties of many magnetic materials, thereby enabling the operation of various magnetic devices, such as multiferroic magnetic field sensors and ferro/ferrimagnetic magneto-static wave filters. We present a magnetic circuit designed to produce a tunable dc magnetic bias field and detail its operating principle. The magnitude of the bias field can be electrically tuned to achieve a desired magnetic field; when not being switched, the achieved field is maintained with zero static power consumption. The magnetic circuit comprises two distinct types of permanent magnets: an NdFeB magnet with relatively high coercivity and an AlNiCo V magnet with relatively low coercivity combined with a tuning coil for adjusting its magnetization. Soft magnetic yoke pieces link the permanent magnets and also define an air gap. Pulses of current through the coil will adjust the remanence of the AlNiCo magnet, thereby changing the flux and field in the air gap. A magnetic bias circuit with a compact volume of 0.27 cm3 has been constructed, providing an adjustable dc magnetic field with a tuning range of 3.7 to 288.5 mT within a 1 mm air gap.
{"title":"A Tunable Magnetic Bias Circuit With Zero Static Power Consumption","authors":"Yixiao Ding;Xuan Wang;Mark G. Allen","doi":"10.1109/LMAG.2025.3541915","DOIUrl":"https://doi.org/10.1109/LMAG.2025.3541915","url":null,"abstract":"Quasi-static magnetic fields can be used to modulate the magnetic and electrical properties of many magnetic materials, thereby enabling the operation of various magnetic devices, such as multiferroic magnetic field sensors and ferro/ferrimagnetic magneto-static wave filters. We present a magnetic circuit designed to produce a tunable dc magnetic bias field and detail its operating principle. The magnitude of the bias field can be electrically tuned to achieve a desired magnetic field; when not being switched, the achieved field is maintained with zero static power consumption. The magnetic circuit comprises two distinct types of permanent magnets: an NdFeB magnet with relatively high coercivity and an AlNiCo V magnet with relatively low coercivity combined with a tuning coil for adjusting its magnetization. Soft magnetic yoke pieces link the permanent magnets and also define an air gap. Pulses of current through the coil will adjust the remanence of the AlNiCo magnet, thereby changing the flux and field in the air gap. A magnetic bias circuit with a compact volume of 0.27 cm<sup>3</sup> has been constructed, providing an adjustable dc magnetic field with a tuning range of 3.7 to 288.5 mT within a 1 mm air gap.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"16 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143637904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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