Pub Date : 2024-11-13DOI: 10.1109/LMAG.2024.3497794
Sheetal Yadav;Monika Sharma;Bijoy K. Kuanr
Magnon–photon hybrid systems have potential applications in quantum information processing. The spatial distribution of magnetic field intensity plays a crucial role in enhancing coupling strength. We have investigated strong magnon–photon coupling using a planar waveguide with defects in the ground for dual-frequency ranging from S to C band. Dual inverted split ring resonators were used as a photon resonator, and a yttrium iron garnet (YIG) pellet acted as a magnon source. The interaction between magnon and photon modes was manipulated by variations in the spatial distribution of the magnetic field along the microstrip line. The ferrite sample was placed at three different positions, viz., A, B, and C. The coupling strength $g$ was tuned from 188 to 281 MHz by varying YIG locations at different positions along the microstrip line. The spin-number-normalized coupling strength was significantly tuned up to 50% by controlling the position of YIG. Hence, it provides another degree of freedom for the qubit information exchange. The other parameters such as cooperativity and coupling constant were also determined. This work paves the way for developing innovative hybrid systems with tunable high-gain magnon–photon coupling systems in planar geometry.
{"title":"Enhancement of Magnon–Photon Coupling Strength: Effect of Spatial Distribution","authors":"Sheetal Yadav;Monika Sharma;Bijoy K. Kuanr","doi":"10.1109/LMAG.2024.3497794","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3497794","url":null,"abstract":"Magnon–photon hybrid systems have potential applications in quantum information processing. The spatial distribution of magnetic field intensity plays a crucial role in enhancing coupling strength. We have investigated strong magnon–photon coupling using a planar waveguide with defects in the ground for dual-frequency ranging from S to C band. Dual inverted split ring resonators were used as a photon resonator, and a yttrium iron garnet (YIG) pellet acted as a magnon source. The interaction between magnon and photon modes was manipulated by variations in the spatial distribution of the magnetic field along the microstrip line. The ferrite sample was placed at three different positions, viz., A, B, and C. The coupling strength \u0000<inline-formula><tex-math>$g$</tex-math></inline-formula>\u0000 was tuned from 188 to 281 MHz by varying YIG locations at different positions along the microstrip line. The spin-number-normalized coupling strength was significantly tuned up to 50% by controlling the position of YIG. Hence, it provides another degree of freedom for the qubit information exchange. The other parameters such as cooperativity and coupling constant were also determined. This work paves the way for developing innovative hybrid systems with tunable high-gain magnon–photon coupling systems in planar geometry.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142938554","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}
To address the prevalent issue of vibrations in long boring tools with a significant length-to-diameter ratio, we have developed a novel controllable damping boring tool. This innovative tool leverages the unique properties of magnetorheological elastomers (MREs) to counteract vibrations effectively. Using ANSYS software, we analyzed the magnetic field within the tool, revealing a direct link between excitation current and magnetic induction intensity within the MRE. Concurrently, experiments confirmed a strong correlation between magnetic induction and the MRE's elastic modulus, highlighting the material's tunable stiffness under varying magnetic fields. Further investigation through modal and harmonic response analyses has unveiled that augmenting the MRE's elastic modulus achieves two objectives. First, it raises the natural frequency of the boring tool. Second, and perhaps more importantly, it significantly diminishes the tool's response amplitude to vibrations. To illustrate, at an excitation current of 0 A, our measurements recorded a response amplitude of 0.31504 mm for the controllable damping boring tool. Furthermore, when the excitation current was increased to 1 A, the response amplitude was notably reduced to 0.1523 mm. These compelling results highlight the MRE controllable damping boring tool's exceptional dynamic adjustment capabilities and its remarkable efficacy in vibration suppression.
{"title":"Controllable Damping Boring Tool Based on Magnetorheological Elastomer","authors":"Xuhui Liu;Bin Wan;Bin Xu;Jing Qi;Xingyu He;Zheng Zhou;Yan Wu","doi":"10.1109/LMAG.2024.3490385","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3490385","url":null,"abstract":"To address the prevalent issue of vibrations in long boring tools with a significant length-to-diameter ratio, we have developed a novel controllable damping boring tool. This innovative tool leverages the unique properties of magnetorheological elastomers (MREs) to counteract vibrations effectively. Using ANSYS software, we analyzed the magnetic field within the tool, revealing a direct link between excitation current and magnetic induction intensity within the MRE. Concurrently, experiments confirmed a strong correlation between magnetic induction and the MRE's elastic modulus, highlighting the material's tunable stiffness under varying magnetic fields. Further investigation through modal and harmonic response analyses has unveiled that augmenting the MRE's elastic modulus achieves two objectives. First, it raises the natural frequency of the boring tool. Second, and perhaps more importantly, it significantly diminishes the tool's response amplitude to vibrations. To illustrate, at an excitation current of 0 A, our measurements recorded a response amplitude of 0.31504 mm for the controllable damping boring tool. Furthermore, when the excitation current was increased to 1 A, the response amplitude was notably reduced to 0.1523 mm. These compelling results highlight the MRE controllable damping boring tool's exceptional dynamic adjustment capabilities and its remarkable efficacy in vibration suppression.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905879","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 : 2024-10-31DOI: 10.1109/LMAG.2024.3490383
Lei Wang;Chenbing Qu;Rong Zhou;Zhangming Zhu
In this letter, a new differential magnetic field probe with high sensitivity is presented. The differential magnetic probe includes a 180° out-of-phase balun, a pair of differential detection loops, and an output port with a 50 Ω impedance match. Unlike conventional magnetic probes with a single detection loop, a pair of differential detection loops is used to measure double magnetic-field components. Moreover, a 180° out-of-phase balun is utilized to process the differential-mode signals from these differential detection loops, which can make these probes directly connected to the oscilloscope and no longer rely on vector network analyzers. Finally, the differential magnetic probe is designed, simulated, and measured to verify the design effectiveness, and a near-field scanning system is used to characterize the developed probe. Measured results reveal that the designed differential magnetic probe not only can measure more magnetic-field energy, but also directly connect to the oscilloscope due to its own differential mode operation function in the out-of-phase balun. Therefore, the probe is very suitable for actual interference source location testing.
{"title":"A New Differential Magnetic Probe With Out-of-Phase Balun and Differential Loops","authors":"Lei Wang;Chenbing Qu;Rong Zhou;Zhangming Zhu","doi":"10.1109/LMAG.2024.3490383","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3490383","url":null,"abstract":"In this letter, a new differential magnetic field probe with high sensitivity is presented. The differential magnetic probe includes a 180° out-of-phase balun, a pair of differential detection loops, and an output port with a 50 Ω impedance match. Unlike conventional magnetic probes with a single detection loop, a pair of differential detection loops is used to measure double magnetic-field components. Moreover, a 180° out-of-phase balun is utilized to process the differential-mode signals from these differential detection loops, which can make these probes directly connected to the oscilloscope and no longer rely on vector network analyzers. Finally, the differential magnetic probe is designed, simulated, and measured to verify the design effectiveness, and a near-field scanning system is used to characterize the developed probe. Measured results reveal that the designed differential magnetic probe not only can measure more magnetic-field energy, but also directly connect to the oscilloscope due to its own differential mode operation function in the out-of-phase balun. Therefore, the probe is very suitable for actual interference source location testing.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142761395","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 : 2024-10-31DOI: 10.1109/LMAG.2024.3490380
J. Schmidtpeter;Proloy T. Das;Y. Zabila;C. Schubert;T. Gundrum;T. Wondrak;D. Makarov
Planar Hall magnetoresistive sensors (PHMRs) are promising candidates for various magnetic sensing applications due to their high sensitivity, low power consumption, and compatibility with integrated circuit technology. However, their performance is often limited by inherent noise sources, impacting their resolution and overall sensitivity. Here the effect of three bilayer structures NiFe(10 nm)/IrMn(10 nm), NiFe(30 nm)/IrMn(10 nm), and NiFe(30 nm)/IrMn(20 nm) on noise levels is investigated at low frequency (DC-25 Hz). This study includes a detailed investigation on the optimization process and noise characteristics of multiring PHMR sensors, focusing on identifying and quantifying the dominant noise sources. The experimental measurements are complemented by a theoretical analysis of noise sources including thermal noise, 1/ f noise, intermixing, and environmental noise. The best magnetic resolution is observed for the NiFe(30 nm)/IrMn(10 nm) structure, which achieves a detectivity below 1.5 nT/√Hz at 10 Hz in a nonshielded environment at room temperature. In addition, a substantial improvement in sensitivity is observed by annealing the sensors at 250 °C for 1 h. The findings of this study contribute to a deeper understanding of noise behavior in PHMR sensors, paving the way for developing strategies to improve their performance for demanding sensing applications at low frequencies.
{"title":"Exchange-Biased Multiring Planar Hall Magnetoresistive Sensors With Nanotesla Resolution in Nonshielded Environments","authors":"J. Schmidtpeter;Proloy T. Das;Y. Zabila;C. Schubert;T. Gundrum;T. Wondrak;D. Makarov","doi":"10.1109/LMAG.2024.3490380","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3490380","url":null,"abstract":"Planar Hall magnetoresistive sensors (PHMRs) are promising candidates for various magnetic sensing applications due to their high sensitivity, low power consumption, and compatibility with integrated circuit technology. However, their performance is often limited by inherent noise sources, impacting their resolution and overall sensitivity. Here the effect of three bilayer structures NiFe(10 nm)/IrMn(10 nm), NiFe(30 nm)/IrMn(10 nm), and NiFe(30 nm)/IrMn(20 nm) on noise levels is investigated at low frequency (DC-25 Hz). This study includes a detailed investigation on the optimization process and noise characteristics of multiring PHMR sensors, focusing on identifying and quantifying the dominant noise sources. The experimental measurements are complemented by a theoretical analysis of noise sources including thermal noise, 1/\u0000<italic>f</i>\u0000 noise, intermixing, and environmental noise. The best magnetic resolution is observed for the NiFe(30 nm)/IrMn(10 nm) structure, which achieves a detectivity below 1.5 nT/√Hz at 10 Hz in a nonshielded environment at room temperature. In addition, a substantial improvement in sensitivity is observed by annealing the sensors at 250 °C for 1 h. The findings of this study contribute to a deeper understanding of noise behavior in PHMR sensors, paving the way for developing strategies to improve their performance for demanding sensing applications at low frequencies.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142798050","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 : 2024-10-24DOI: 10.1109/LMAG.2024.3484957
Steven Louis;Hannah Bradley;Cody Trevillian;Andrei Slavin;Vasyl Tyberkevych
This letter presents a novel spiking artificial neuron design based on a combined spin valve/magnetic tunnel junction (SV/MTJ). Traditional hardware used in artificial intelligence and machine learning faces significant challenges related to high power consumption and scalability. To address these challenges, spintronic neurons, which can mimic biologically inspired neural behaviors, offer a promising solution. We present a model of an SV/MTJ-based neuron that uses technologies that have been successfully integrated with CMOS in commercially available applications. The operational dynamics of the neuron are derived analytically through the Landau–Lifshitz-Gilbert–Slonczewski equation, demonstrating its ability to replicate key spiking characteristics of biological neurons such as response latency and refractive behavior. Simulation results indicate that the proposed neuron design can operate on a timescale of about 1 ns, without any bias current and with power consumption as low as 50 ${mu }$ W.
{"title":"Spintronic Neuron Using a Magnetic Tunnel Junction for Low-Power Neuromorphic Computing","authors":"Steven Louis;Hannah Bradley;Cody Trevillian;Andrei Slavin;Vasyl Tyberkevych","doi":"10.1109/LMAG.2024.3484957","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3484957","url":null,"abstract":"This letter presents a novel spiking artificial neuron design based on a combined spin valve/magnetic tunnel junction (SV/MTJ). Traditional hardware used in artificial intelligence and machine learning faces significant challenges related to high power consumption and scalability. To address these challenges, spintronic neurons, which can mimic biologically inspired neural behaviors, offer a promising solution. We present a model of an SV/MTJ-based neuron that uses technologies that have been successfully integrated with CMOS in commercially available applications. The operational dynamics of the neuron are derived analytically through the Landau–Lifshitz-Gilbert–Slonczewski equation, demonstrating its ability to replicate key spiking characteristics of biological neurons such as response latency and refractive behavior. Simulation results indicate that the proposed neuron design can operate on a timescale of about 1 ns, without any bias current and with power consumption as low as 50 \u0000<inline-formula><tex-math>${mu }$</tex-math></inline-formula>\u0000W.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142672079","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 : 2024-10-21DOI: 10.1109/LMAG.2024.3484271
Mohammad Asif;Prashant Kumar;Mirza Tariq Beg;M. Nizamuddin;Bijoy Kumar Kuanr
In the present investigation, we have demonstrated the effect of different substrates (Si, SiO 2${rm{, }};text{and};text {{A}}{{{text {l}}}_{2}}{{{text {O}}}_{3}}$ ) and deposition temperatures ( TD = 27 °C to 450 °C) of sputtered Fe 80 Co 20 ferromagnetic thin films of 30 nm thickness on their microstructural, static, and dynamic properties. The lowest value of Gilbert damping (α eff ) of 5.1 $ times, 10$−3 with a high saturation magnetization ( MS ) is the outcome of the improved atomic ordering and overall film crystallinity with ultralow interfacial roughness (0.23 ± 0.03 nm) of 400 °C grown films. The structural analysis from atomic force microscopy depicts temperature-dependent improvement in films grown at 400 °C. From ferromagnetic resonance and vibrating sample magnetometry experiments, magnetization was determined to be the highest MS$ approx text {1628.8} {rm{emu/cc}}$ for the films grown at 400 °C. We have validated the above-mentioned experimental data through micromagnetic simulation using ubermag and an object-oriented micromagnetic framework that is used in backend for computation.
{"title":"Relaxation Dynamics of Sputtered Fe80Co20 Thin Films on Different Substrates: Micromagnetic Validation","authors":"Mohammad Asif;Prashant Kumar;Mirza Tariq Beg;M. Nizamuddin;Bijoy Kumar Kuanr","doi":"10.1109/LMAG.2024.3484271","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3484271","url":null,"abstract":"In the present investigation, we have demonstrated the effect of different substrates (Si, SiO\u0000<sub>2</sub>\u0000<inline-formula><tex-math>${rm{, }};text{and};text {{A}}{{{text {l}}}_{2}}{{{text {O}}}_{3}}$</tex-math></inline-formula>\u0000) and deposition temperatures (\u0000<italic>T<sub>D</sub></i>\u0000 = 27 °C to 450 °C) of sputtered Fe\u0000<sub>80</sub>\u0000Co\u0000<sub>20</sub>\u0000 ferromagnetic thin films of 30 nm thickness on their microstructural, static, and dynamic properties. The lowest value of Gilbert damping (α\u0000<sub>eff</sub>\u0000) of 5.1 \u0000<inline-formula><tex-math>$ times, 10$</tex-math></inline-formula>\u0000<sup>−3</sup>\u0000 with a high saturation magnetization (\u0000<italic>M<sub>S</sub></i>\u0000) is the outcome of the improved atomic ordering and overall film crystallinity with ultralow interfacial roughness (0.23 ± 0.03 nm) of 400 °C grown films. The structural analysis from atomic force microscopy depicts temperature-dependent improvement in films grown at 400 °C. From ferromagnetic resonance and vibrating sample magnetometry experiments, magnetization was determined to be the highest \u0000<italic>M<sub>S</sub></i>\u0000 \u0000<inline-formula><tex-math>$ approx text {1628.8} {rm{emu/cc}}$</tex-math></inline-formula>\u0000 for the films grown at 400 °C. We have validated the above-mentioned experimental data through micromagnetic simulation using ubermag and an object-oriented micromagnetic framework that is used in backend for computation.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142777579","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 : 2024-10-17DOI: 10.1109/LMAG.2024.3483069
Mengting Zou;Xilai Bao;Xinze Li;Yali Xie;Huali Yang;Lili Pan;Xiaojian Zhu;Run-Wei Li
Spin valves have received significant attention in the realm of flexible magnetic materials and devices due to their advantages of rapid response and high integration. Despite these benefits, the practical application of spin valves in wearable devices is constrained by their low stretchability and strain stability under tensile strain. Here, by designing spin valves with zigzag-wrinkled structure, we demonstrated that the magnetotransport properties of our spin valves remained unaffected under 25% biaxial tensile strain, revealing stretchability and strain stability. These outstanding performances are related to the zigzag-wrinkled structure generated after releasing the biaxial prestrain in polymer polydimethylsiloxane substrates. The flattening of the zigzag wrinkles under the biaxial tensile strain releases the direct effect of strain on the metal multilayers, thereby maintaining sensing performances upon stretching. This innovative design paves the way for the development of robust, flexible magnetic devices suitable for wearable technology.
{"title":"Biaxially Stretchable Spin Valves With Stable Magnetic Sensing Performance","authors":"Mengting Zou;Xilai Bao;Xinze Li;Yali Xie;Huali Yang;Lili Pan;Xiaojian Zhu;Run-Wei Li","doi":"10.1109/LMAG.2024.3483069","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3483069","url":null,"abstract":"Spin valves have received significant attention in the realm of flexible magnetic materials and devices due to their advantages of rapid response and high integration. Despite these benefits, the practical application of spin valves in wearable devices is constrained by their low stretchability and strain stability under tensile strain. Here, by designing spin valves with zigzag-wrinkled structure, we demonstrated that the magnetotransport properties of our spin valves remained unaffected under 25% biaxial tensile strain, revealing stretchability and strain stability. These outstanding performances are related to the zigzag-wrinkled structure generated after releasing the biaxial prestrain in polymer polydimethylsiloxane substrates. The flattening of the zigzag wrinkles under the biaxial tensile strain releases the direct effect of strain on the metal multilayers, thereby maintaining sensing performances upon stretching. This innovative design paves the way for the development of robust, flexible magnetic devices suitable for wearable technology.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636398","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 : 2024-10-14DOI: 10.1109/LMAG.2024.3479924
Yang-Ki Hong;Jihoon Park;Hang Nam Ok;Minyeong Choi;Md Abdul Wahed;Myung-Hwa Jung;Chang-Dong Yeo
Monoclinic Fe 3 Se 4 was synthesized using a ceramic method. Mössbauer spectroscopy and density functional theory were used to investigate the physical origins of its ferrimagnetism and high coercivity. At 78 K, 12 Mössbauer absorption lines were observed. These lines are composed of two subspectra, A and B, corresponding to Fe atoms at the 2 a and 4 i sites, respectively. At 320 K, the Mössbauer spectrum collapsed, indicating a transition from a ferrimagnetic to a paramagnetic state. This temperature is close to the Curie temperature ( T C ) of 331 or 315 K reported in the literature. The analysis of local structural symmetry confirmed that the Fe atoms in the 2 a sites are more symmetrically coordinated with neighboring Se atoms than those in the 4 i sites. Therefore, the Fe atoms in the 2 a sites exhibit a higher hyperfine magnetic field (HMF) of 225 kOe and a weaker quadrupole splitting (QS) of 0.17 mm/s than the Fe atoms in the 4 i sites, which exhibit an HMF of 105 kOe and a QS of 0.55 mm/s. Our density functional study confirmed that Fe 3 Se 4 exhibits ferrimagnetic behavior, with a magnetic moment of 4.48 µ B /u.c. and a T C of 354 K. Fe 3 Se 4 shows a high magnetocrystalline anisotropy constant ( K u ) of 0.9 × 10 6 erg/cm 3 . This high K u value is attributed to the Fe atoms at the 4 i sites. It is suggested that the high coercivity of Fe 3 Se 4 , as reported in the literature, is due to the distorted 4 i site, which experiences the Jahn–Teller effect.
采用陶瓷法合成了单斜Fe3Se4。研究人员利用莫斯鲍尔光谱学和密度泛函理论研究了其铁磁性和高矫顽力的物理根源。在 78 K 时，观察到 12 条莫斯鲍尔吸收线。这些线由两个子谱 A 和 B 组成，分别对应于 2a 和 4i 位点上的铁原子。在 320 K 时，莫斯鲍尔光谱坍缩，表明铁磁态向顺磁态过渡。这一温度接近文献报道的居里温度（TC）331 或 315 K。对局部结构对称性的分析证实，与 4i 位点的铁原子相比，2a 位点的铁原子与相邻 Se 原子的配位更对称。因此，2a 位点的铁原子比 4i 位点的铁原子表现出更高的超频磁场（HMF）（225 kOe）和更弱的四极分裂（QS）（0.17 mm/s），后者表现出 105 kOe 的 HMF 和 0.55 mm/s 的 QS。我们的密度泛函研究证实，Fe3Se4 具有铁磁性，磁矩为 4.48 µB/u.c.，TC 为 354 K。这一高 Ku 值归因于 4i 位点上的铁原子。根据文献报道，Fe3Se4 的高矫顽力是由于 4i 位点发生了扭曲，从而产生了贾恩-泰勒效应。
{"title":"Mössbauer and Density Functional Studies of Ferrimagnetic Fe3Se4","authors":"Yang-Ki Hong;Jihoon Park;Hang Nam Ok;Minyeong Choi;Md Abdul Wahed;Myung-Hwa Jung;Chang-Dong Yeo","doi":"10.1109/LMAG.2024.3479924","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3479924","url":null,"abstract":"Monoclinic Fe\u0000<sub>3</sub>\u0000Se\u0000<sub>4</sub>\u0000 was synthesized using a ceramic method. Mössbauer spectroscopy and density functional theory were used to investigate the physical origins of its ferrimagnetism and high coercivity. At 78 K, 12 Mössbauer absorption lines were observed. These lines are composed of two subspectra, A and B, corresponding to Fe atoms at the 2\u0000<italic>a</i>\u0000 and 4\u0000<italic>i</i>\u0000 sites, respectively. At 320 K, the Mössbauer spectrum collapsed, indicating a transition from a ferrimagnetic to a paramagnetic state. This temperature is close to the Curie temperature (\u0000<italic>T</i>\u0000<sub>C</sub>\u0000) of 331 or 315 K reported in the literature. The analysis of local structural symmetry confirmed that the Fe atoms in the 2\u0000<italic>a</i>\u0000 sites are more symmetrically coordinated with neighboring Se atoms than those in the 4\u0000<italic>i</i>\u0000 sites. Therefore, the Fe atoms in the 2\u0000<italic>a</i>\u0000 sites exhibit a higher hyperfine magnetic field (HMF) of 225 kOe and a weaker quadrupole splitting (QS) of 0.17 mm/s than the Fe atoms in the 4\u0000<italic>i</i>\u0000 sites, which exhibit an HMF of 105 kOe and a QS of 0.55 mm/s. Our density functional study confirmed that Fe\u0000<sub>3</sub>\u0000Se\u0000<sub>4</sub>\u0000 exhibits ferrimagnetic behavior, with a magnetic moment of 4.48 µ\u0000<sub>B</sub>\u0000/u.c. and a \u0000<italic>T</i>\u0000<sub>C</sub>\u0000 of 354 K. Fe\u0000<sub>3</sub>\u0000Se\u0000<sub>4</sub>\u0000 shows a high magnetocrystalline anisotropy constant (\u0000<italic>K</i>\u0000<sub>u</sub>\u0000) of 0.9 × 10\u0000<sup>6</sup>\u0000 erg/cm\u0000<sup>3</sup>\u0000. This high \u0000<italic>K</i>\u0000<sub>u</sub>\u0000 value is attributed to the Fe atoms at the 4\u0000<italic>i</i>\u0000 sites. It is suggested that the high coercivity of Fe\u0000<sub>3</sub>\u0000Se\u0000<sub>4</sub>\u0000, as reported in the literature, is due to the distorted 4\u0000<italic>i</i>\u0000 site, which experiences the Jahn–Teller effect.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142636397","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 : 2024-10-14DOI: 10.1109/LMAG.2024.3479932
Kuntal Roy
Topological insulators and giant spin-orbit torque switching of nanomagnets are among the frontier topics for the development of energy-efficient spintronic devices. Spin-circuit representations involving different materials and phenomena are quite well established now for their prowess of interpreting experimental results and then designing complex and efficient functional devices. Here, we construct the spin-circuit representation of spin pumping into topological insulators, considering both the bulk and surface states with parallel channels, which allows for the interpretation of practical experimental results. We show that the high increase in effective spin mixing conductance and inverse spin Hall voltages cannot be explained by the low-conductive bulk states of topological insulators. We determine a high spin Hall angle close to the maximum magnitude of one from experimental results and address the controversy in the literature by correctly estimating the parameters involved in the system. With an eye to designing energy-efficient spin devices, we further employ a spin-sink layer in the spin-circuit formalism to increase the effective spin mixing conductance at low thicknesses and double the inverse spin Hall voltage.
{"title":"Spin-Circuit Representation of Spin Pumping Into Topological Insulators and Determination of Giant Spin Hall Angle and Inverse Spin Hall Voltages","authors":"Kuntal Roy","doi":"10.1109/LMAG.2024.3479932","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3479932","url":null,"abstract":"Topological insulators and giant spin-orbit torque switching of nanomagnets are among the frontier topics for the development of energy-efficient spintronic devices. Spin-circuit representations involving different materials and phenomena are quite well established now for their prowess of interpreting experimental results and then designing complex and efficient functional devices. Here, we construct the spin-circuit representation of spin pumping into topological insulators, considering both the bulk and surface states with parallel channels, which allows for the interpretation of practical experimental results. We show that the high increase in effective spin mixing conductance and inverse spin Hall voltages cannot be explained by the low-conductive bulk states of topological insulators. We determine a high spin Hall angle close to the maximum magnitude of one from experimental results and address the controversy in the literature by correctly estimating the parameters involved in the system. With an eye to designing energy-efficient spin devices, we further employ a spin-sink layer in the spin-circuit formalism to increase the effective spin mixing conductance at low thicknesses and double the inverse spin Hall voltage.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142810338","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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