IEEE Magnetics Letters最新文献

{"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}

{"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}

{"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}

{"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\u0000₂\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_D</i>\u0000 = 27 °C to 450 °C) of sputtered Fe\u0000₈₀\u0000Co\u0000₂₀\u0000 ferromagnetic thin films of 30 nm thickness on their microstructural, static, and dynamic properties. The lowest value of Gilbert damping (α\u0000_eff\u0000) of 5.1 \u0000<inline-formula><tex-math>$ times, 10$</tex-math></inline-formula>\u0000⁻³\u0000 with a high saturation magnetization (\u0000<italic>M_S</i>\u0000) is the outcome of the improved atomic ordering and overall film crystallinity with ultralow interfacial roughness (0.23 ± 0.03 nm) of 400 °C grown films. The structural analysis from atomic force microscopy depicts temperature-dependent improvement in films grown at 400 °C. From ferromagnetic resonance and vibrating sample magnetometry experiments, magnetization was determined to be the highest \u0000<italic>M_S</i>\u0000 \u0000<inline-formula><tex-math>$ 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}

{"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}

{"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\u0000₃\u0000Se\u0000₄\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_C\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\u0000₃\u0000Se\u0000₄\u0000 exhibits ferrimagnetic behavior, with a magnetic moment of 4.48 µ\u0000_B\u0000/u.c. and a \u0000<italic>T</i>\u0000_C\u0000 of 354 K. Fe\u0000₃\u0000Se\u0000₄\u0000 shows a high magnetocrystalline anisotropy constant (\u0000<italic>K</i>\u0000_u\u0000) of 0.9 × 10\u0000⁶\u0000 erg/cm\u0000³\u0000. This high \u0000<italic>K</i>\u0000_u\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\u0000₃\u0000Se\u0000₄\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}

{"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}

{"title":"Micromagnetic Modeling of Parametric Amplification of Forward Volume Spin Waves by Noncollinear Surface Acoustic Waves","authors":"Carson Rivard;Albrecht Jander;Pallavi Dhagat","doi":"10.1109/LMAG.2024.3479922","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3479922","url":null,"abstract":"Micromagnetic modeling is used to simulate the parametric amplification of forward volume spin waves by a surface acoustic wave (SAW) traveling noncollinearly in a yttrium–iron–garnet thin film. The angle of incidence between the signal spin wave and the SAW pump determines the strength of parametric coupling as well as the propagation direction of the resulting idler spin wave. In a collinear arrangement, where the spin wave and SAW travel together, the acoustic pump amplitude needed to achieve amplification is greater than the threshold for the parametric generation of spin waves from the thermal background. However, in a noncollinear arrangement with >35° angle of incidence between the signal spin wave and SAW pump, the coupling is enhanced and allows for continuous amplification of spin waves by more than 10× without simultaneously resulting in unconstrained growth of thermal spin waves. The angular dependence of the parametric coupling strength, as determined from the simulations, agrees qualitatively with theoretical predictions.","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":"142713897","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}

{"title":"Multiresonance Microwave Absorption in Ti–Mn Substituted Barium Hexaferrite Composites","authors":"M. J. Vazquez Bernardez;J. Solano;M. Bailleul;N. Vukadinovic;D. Stoeffler;C. Lefevre","doi":"10.1109/LMAG.2024.3479936","DOIUrl":"https://doi.org/10.1109/LMAG.2024.3479936","url":null,"abstract":"Ti–Mn substituted Ba(TiMn)\u0000_<i>x</i>\u0000Fe\u0000_12-2<i>x</i>\u0000O\u0000₁₉\u0000 hexaferrite randomly oriented composites were obtained by conventional ceramic synthesis. At zero applied magnetic field, in its polycrystalline powder form, this ferrimagnetic compound exhibits a multipeak permeability spectrum with two high-frequency resonances that converge under the action of an external magnetic field. We conduct a broad-band ferromagnetic resonances characterization of this system under an applied magnetic field between 0 and 2 T and integrate the results with micromagnetic simulations to investigate the presence of high-frequency resonating magnetic domains contingent upon the sample's microstructure. Simulations show that magnetic domains separated by domain walls upon each magnetic particle are responsible for the multipeak resonance in the Ka-band. By combining the simulated spectra with an effective medium theory accounting for the dilution effect of the dielectric matrix, we reproduce the zero-field permeability spectra.","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":"142679319","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}

{"title":"Role of Shape Ellipticity on Dipole-Exchange Spin Waves in Ferromagnetic Nanorings","authors":"Yassin Elmeligi;Bushra Hussain;Michael G. Cottam","doi":"10.1109/LMAG.2024.3461575","DOIUrl":"10.1109/LMAG.2024.3461575","url":null,"abstract":"The properties of the quantized spin-wave frequencies and the transition field between the two stable magnetization states (the low-field vortex state and the higher-field onion state) are studied for elliptical nanorings. The dependences of these quantities on the nanoring sizes and the degree of ellipticity are examined over a wide range of values for the applied magnetic field and its orientation. The novel effects introduced when the symmetry axes of the inner elliptical edges of the rings are rotated relative to those of the outer elliptical edge are also studied. To characterize these effects, our theory makes use of a Hamiltonian-based dipole-exchange methodology, adapted from that used to elucidate the spin-wave modes in circular nanorings. It is found that spin-wave frequencies and the behavior of the transition field(s) depend sensitively on the degree of ellipticity, the rotation angle of the inner elliptical edge with respect to the outer elliptical edge, and the direction of the applied field relative to the nanoring axes.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"15 ","pages":"1-5"},"PeriodicalIF":1.1,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142259502","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}