Pub Date : 2022-12-02DOI: 10.1109/LMAG.2022.3226031
Brooke C. McGoldrick;Jonathan Z. Sun
Probabilistic bits (p-bits) based on magnetic tunnel junctions are of recent interest in probabilistic and neuromorphic computing architectures based on their small size, high operating speeds, and truly stochastic nature. In practical systems, the output probability of the bit can be tuned by an applied current, which is generally characterized by a quasi-static tuning curve. In this letter, we instead focus on the finite time it takes the p-bit's probabilistic distribution to respond to an applied bias current. We find that this settling time is in the range of hundreds of picoseconds for a typical junction, and is highly dependent on various parameters, including the device size, material properties, and magnitude of the applied current. These results provide a baseline understanding of the dynamic properties of a nanomagnetic p-bit's probability distribution, which is helpful for p-bit-related system architecture discussions.
{"title":"Settling Time of Current-Tunable Probabilistic Bit's Distribution","authors":"Brooke C. McGoldrick;Jonathan Z. Sun","doi":"10.1109/LMAG.2022.3226031","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3226031","url":null,"abstract":"Probabilistic bits (p-bits) based on magnetic tunnel junctions are of recent interest in probabilistic and neuromorphic computing architectures based on their small size, high operating speeds, and truly stochastic nature. In practical systems, the output probability of the bit can be tuned by an applied current, which is generally characterized by a quasi-static tuning curve. In this letter, we instead focus on the finite time it takes the p-bit's probabilistic distribution to respond to an applied bias current. We find that this settling time is in the range of hundreds of picoseconds for a typical junction, and is highly dependent on various parameters, including the device size, material properties, and magnitude of the applied current. These results provide a baseline understanding of the dynamic properties of a nanomagnetic p-bit's probability distribution, which is helpful for p-bit-related system architecture discussions.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741588","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}
Wearable and implantable devices (WIDs) come with several separate blocks such as preprocessing units, memory, and data transmission blocks. Hence, in this letter, we present the concept of memory and communication-in-logic (MCL) using a magnetic tunnel junction (MTJ). Here, MTJ is presented as a memory device as well as an oscillator for communication purposes. Vortex-based spin-torque nanooscillators (V-STNO) and precessional STNOs (P-STNO) generate a microwave frequency range (a few hundred MHz to a few GHz) wherein the frequency readout technique using the spin-torque diode is implemented for memory read function. In this work, a 300 nm nanodisk V-STNO generates 296 and 312 MHz frequency for two states of chirality (a characteristic of magnetic vortex), respectively. These different frequencies can be sensed for a bit “0”/ “1” read out through which the data from WIDs can be transmitted in a more energy- and area-efficient way. The output power emission is 3.22 and 1.76 µW for bit “1” and “0,” respectively, for V-STNO, which is three orders of magnitude larger than that of P-STNO. Finally, we demonstrate that V-STNO can transmit data up to 10 m in the air medium, which is much longer than P-STNO (0.24 m).
{"title":"Memory and Communication-in-Logic Using Vortex and Precessional Oscillations in a Magnetic Tunnel Junction","authors":"Sonal Shreya;Milad Zamani;Yaseer Rezaeiyan;Hamdam Ghanatian;Tim Böhnert;Alex S. Jenkins;Ricardo Ferreira;Hooman Farkhani;Farshad Moradi","doi":"10.1109/LMAG.2022.3224676","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3224676","url":null,"abstract":"Wearable and implantable devices (WIDs) come with several separate blocks such as preprocessing units, memory, and data transmission blocks. Hence, in this letter, we present the concept of memory and communication-in-logic (MCL) using a magnetic tunnel junction (MTJ). Here, MTJ is presented as a memory device as well as an oscillator for communication purposes. Vortex-based spin-torque nanooscillators (V-STNO) and precessional STNOs (P-STNO) generate a microwave frequency range (a few hundred MHz to a few GHz) wherein the frequency readout technique using the spin-torque diode is implemented for memory read function. In this work, a 300 nm nanodisk V-STNO generates 296 and 312 MHz frequency for two states of chirality (a characteristic of magnetic vortex), respectively. These different frequencies can be sensed for a bit “0”/ “1” read out through which the data from WIDs can be transmitted in a more energy- and area-efficient way. The output power emission is 3.22 and 1.76 µW for bit “1” and “0,” respectively, for V-STNO, which is three orders of magnitude larger than that of P-STNO. Finally, we demonstrate that V-STNO can transmit data up to 10 m in the air medium, which is much longer than P-STNO (0.24 m).","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-11-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741587","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}
In this letter, we study the effect of buffer and cap layers on thermally stable perpendicular magnetic anisotropy (PMA) in a buffer/CoFeB/MgO/cap structure. Not only is the buffer layer crucial, but the type of cap layer also affects the thermal stability of PMA. Relative to the Ta samples, the W samples that adopt a W buffer or cap layer acquire a wider PMA thickness range for further increasing the PMA thermal stability in magnetic random-access memory applications. And similarly for the W buffer layer, the annealing temperature for the W cap layer also increases by 30 °C (from 270 °C to 300 °C). Via detailed anomalous Hall effect measurements, the thermal stability of PMA in buffer/CoFeB/MgO/cap was investigated. This work provides a promising way to obtain high thermal stability of PMA in CoFeB-MgO-based spintronic applications, and it is significant for designing next-generation information storage devices.
{"title":"Effect of Buffer and Cap Layer on Thermally Stable Perpendicular Magnetic Anisotropy in Buffer/CoFeB/MgO/Cap Structure","authors":"Wei Du;Mengli Liu;Fengxuan Han;Hua Su;Bo Liu;Hao Meng;Xiaoli Tang","doi":"10.1109/LMAG.2022.3221050","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3221050","url":null,"abstract":"In this letter, we study the effect of buffer and cap layers on thermally stable perpendicular magnetic anisotropy (PMA) in a buffer/CoFeB/MgO/cap structure. Not only is the buffer layer crucial, but the type of cap layer also affects the thermal stability of PMA. Relative to the Ta samples, the W samples that adopt a W buffer or cap layer acquire a wider PMA thickness range for further increasing the PMA thermal stability in magnetic random-access memory applications. And similarly for the W buffer layer, the annealing temperature for the W cap layer also increases by 30 °C (from 270 °C to 300 °C). Via detailed anomalous Hall effect measurements, the thermal stability of PMA in buffer/CoFeB/MgO/cap was investigated. This work provides a promising way to obtain high thermal stability of PMA in CoFeB-MgO-based spintronic applications, and it is significant for designing next-generation information storage devices.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741586","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 : 2022-11-03DOI: 10.1109/LMAG.2022.3219234
Gyuyeol Kong;Taehyoung Kim;Minchae Jung
An iterative multihead multitrack detection scheme for bit-patterned media recording is described in this letter. The scheme employs two iterative strategies with multihead, multitrack detection where three tracks are simultaneously processed to accurately estimate the channel with track misregistration (TMR) and effectively detect the data by using intertrack interference ( ITI ) information with high reliability. The first outer iteration aims to compensate for the TMR effect, and the second inner iteration aims to improve the reliability of the data. In the outer iteration, the TMR effect is compensated by modifying the generalized partial response (GPR) target to a channel that reflects the TMR estimated by a TMR estimator using an expectation and maximization algorithm. In the inner iteration, iterative equalization and decoding (IED) is conducted between the two-dimensional partial response maximum-likelihood detector and the low-density parity check decoder based on the revised GPR target. Since each track has a different channel performance according to the amount of ITI information in the multitrack detection, we design the GPR target and the code rate separately for each track to maximize the overall channel performance. The bit error rate performances of the proposed IED scheme are compared with the conventional IED scheme when the areal density is 2 $text{Tb/in}^{2}$ . Simulation results show that the IED scheme has more than 2 dB gain compared with the conventional IED scheme for 30 $%$ TMR.
{"title":"Iterative Multihead Multitrack Detection Scheme for Bit-Patterned Media Recording","authors":"Gyuyeol Kong;Taehyoung Kim;Minchae Jung","doi":"10.1109/LMAG.2022.3219234","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3219234","url":null,"abstract":"An iterative multihead multitrack detection scheme for bit-patterned media recording is described in this letter. The scheme employs two iterative strategies with multihead, multitrack detection where three tracks are simultaneously processed to accurately estimate the channel with track misregistration (TMR) and effectively detect the data by using intertrack interference (\u0000<bold>ITI</b>\u0000) information with high reliability. The first outer iteration aims to compensate for the TMR effect, and the second inner iteration aims to improve the reliability of the data. In the outer iteration, the TMR effect is compensated by modifying the generalized partial response (GPR) target to a channel that reflects the TMR estimated by a TMR estimator using an expectation and maximization algorithm. In the inner iteration, iterative equalization and decoding (IED) is conducted between the two-dimensional partial response maximum-likelihood detector and the low-density parity check decoder based on the revised GPR target. Since each track has a different channel performance according to the amount of ITI information in the multitrack detection, we design the GPR target and the code rate separately for each track to maximize the overall channel performance. The bit error rate performances of the proposed IED scheme are compared with the conventional IED scheme when the areal density is 2 \u0000<inline-formula><tex-math>$text{Tb/in}^{2}$</tex-math></inline-formula>\u0000. Simulation results show that the IED scheme has more than 2 dB gain compared with the conventional IED scheme for 30\u0000<inline-formula><tex-math>$%$</tex-math></inline-formula>\u0000 TMR.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741659","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 : 2022-09-26DOI: 10.1109/LMAG.2022.3209647
Martina Kiechle;Levente Maucha;Valentin Ahrens;Carsten Dubs;Wolfgang Porod;Gyorgy Csaba;Markus Becherer;Adam Papp
In this letter, we present the design and experimental realization of a device that acts like a spin-wave lens i.e., it focuses spin waves to a specified location. The structure of the lens does not resemble any conventional lens design. It is a nonintuitive pattern produced by a machine-learning algorithm. As a spin-wave design tool, we used our custom micromagnetic solver SpinTorch, which has built-in automatic gradient calculation and can perform backpropagation through time for spin-wave propagation. The training itself is performed with the saturation magnetization of a yttrium-iron-garnet (YIG) film as a variable parameter, with the goal to guide spin waves to a predefined location. We verified the operation of the device in the widely used mumax $^{3}$ micromagnetic solver, and by experimental realization. For the experimental implementation, we developed a technique to create effective saturation-magnetization landscapes in YIG by direct focused-ion-beam (FIB) irradiation. This allows us to rapidly transfer the nanoscale design patterns to the YIG medium, without patterning the material by etching. We measured the effective saturation magnetization corresponding to the FIB dose levels in advance and used this mapping to translate the designed scatterer to the required dose levels. Our demonstration serves as a proof of concept for a workflow that can be used to realize more sophisticated spin-wave devices with complex functionality, e.g., spin-wave signal processors, or neuromorphic devices.
{"title":"Experimental Demonstration of a Spin-Wave Lens Designed With Machine Learning","authors":"Martina Kiechle;Levente Maucha;Valentin Ahrens;Carsten Dubs;Wolfgang Porod;Gyorgy Csaba;Markus Becherer;Adam Papp","doi":"10.1109/LMAG.2022.3209647","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3209647","url":null,"abstract":"In this letter, we present the design and experimental realization of a device that acts like a spin-wave lens i.e., it focuses spin waves to a specified location. The structure of the lens does not resemble any conventional lens design. It is a nonintuitive pattern produced by a machine-learning algorithm. As a spin-wave design tool, we used our custom micromagnetic solver SpinTorch, which has built-in automatic gradient calculation and can perform backpropagation through time for spin-wave propagation. The training itself is performed with the saturation magnetization of a yttrium-iron-garnet (YIG) film as a variable parameter, with the goal to guide spin waves to a predefined location. We verified the operation of the device in the widely used mumax\u0000<inline-formula><tex-math>$^{3}$</tex-math></inline-formula>\u0000 micromagnetic solver, and by experimental realization. For the experimental implementation, we developed a technique to create effective saturation-magnetization landscapes in YIG by direct focused-ion-beam (FIB) irradiation. This allows us to rapidly transfer the nanoscale design patterns to the YIG medium, without patterning the material by etching. We measured the effective saturation magnetization corresponding to the FIB dose levels in advance and used this mapping to translate the designed scatterer to the required dose levels. Our demonstration serves as a proof of concept for a workflow that can be used to realize more sophisticated spin-wave devices with complex functionality, e.g., spin-wave signal processors, or neuromorphic devices.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741658","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 : 2022-09-12DOI: 10.1109/LMAG.2022.3205881
Xiangang Li;Shenggang Yan;Jianguo Liu;Youyu Yan
There are various technology routes for the localization of magnetic targets. Among them, localization methods based on magnetic gradient tensor invariants have remarkable preponderance. For instance, such invariants are not sensitive to the jitter of the coordinate system, which means this kind of method can be very suitable for application in moving carriers. The traditional classic method contains ellipse error, which cannot be simply ignored. In order to eliminate this error, the general solution of the location vector is derived in this letter. Three methods for solving the general solution are given. To validate the effectiveness of the methods, the localization problem of the measurement array surrounding a static target is simulated. In this simulation, the localization results of the traditional method and the proposed methods are analyzed and compared. The conclusions show that the developed methods successfully remove the ellipse error and improve the localization accuracy.
{"title":"Novel Magnetic Localization Methods for Minimizing the Ellipse Error Based on Tensor Invariants","authors":"Xiangang Li;Shenggang Yan;Jianguo Liu;Youyu Yan","doi":"10.1109/LMAG.2022.3205881","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3205881","url":null,"abstract":"There are various technology routes for the localization of magnetic targets. Among them, localization methods based on magnetic gradient tensor invariants have remarkable preponderance. For instance, such invariants are not sensitive to the jitter of the coordinate system, which means this kind of method can be very suitable for application in moving carriers. The traditional classic method contains ellipse error, which cannot be simply ignored. In order to eliminate this error, the general solution of the location vector is derived in this letter. Three methods for solving the general solution are given. To validate the effectiveness of the methods, the localization problem of the measurement array surrounding a static target is simulated. In this simulation, the localization results of the traditional method and the proposed methods are analyzed and compared. The conclusions show that the developed methods successfully remove the ellipse error and improve the localization accuracy.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67902598","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 : 2022-08-26DOI: 10.1109/LMAG.2022.3202135
Rahnuma Rahman;Supriyo Bandyopadhyay
Binary stochastic neurons (BSNs) are excellent hardware accelerators for machine learning. A popular platform for implementing them is low- or zero-energy barrier nanomagnets possessing in-plane magnetic anisotropy (e.g., circular disks or quasi-elliptical disks with very small eccentricity). Unfortunately, small geometric variations in the lateral shapes of such nanomagnets can produce large changes in the BSN response times if the nanomagnets are made of common metallic ferromagnets (Co, Ni, Fe) with large saturation magnetization. In addition, the response times become very sensitive to initial conditions, i.e., the initial magnetization orientation. In this letter, we show that if the nanomagnets are made of dilute magnetic semiconductors with much smaller saturation magnetization than common metallic ferromagnets, then the variability in their response times (due to shape variations and variation in the initial condition) is drastically suppressed. This significantly reduces the device-to-device variation, which is a serious challenge for large-scale neuromorphic systems. A simple material choice can, therefore, alleviate one of the most aggravating problems in probabilistic computing with nanomagnets.
{"title":"Robustness of Binary Stochastic Neurons Implemented With Low Barrier Nanomagnets Made of Dilute Magnetic Semiconductors","authors":"Rahnuma Rahman;Supriyo Bandyopadhyay","doi":"10.1109/LMAG.2022.3202135","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3202135","url":null,"abstract":"Binary stochastic neurons (BSNs) are excellent hardware accelerators for machine learning. A popular platform for implementing them is low- or zero-energy barrier nanomagnets possessing in-plane magnetic anisotropy (e.g., circular disks or quasi-elliptical disks with very small eccentricity). Unfortunately, small geometric variations in the lateral shapes of such nanomagnets can produce large changes in the BSN response times if the nanomagnets are made of common metallic ferromagnets (Co, Ni, Fe) with large saturation magnetization. In addition, the response times become very sensitive to initial conditions, i.e., the initial magnetization orientation. In this letter, we show that if the nanomagnets are made of dilute magnetic semiconductors with much smaller saturation magnetization than common metallic ferromagnets, then the variability in their response times (due to shape variations and variation in the initial condition) is drastically suppressed. This significantly reduces the device-to-device variation, which is a serious challenge for large-scale neuromorphic systems. A simple material choice can, therefore, alleviate one of the most aggravating problems in probabilistic computing with nanomagnets.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-4"},"PeriodicalIF":1.2,"publicationDate":"2022-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67902601","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}
In this letter, a spintronic true random number generator (TRNG) is designed using the stochastic switching feature of the magnetic tunnel junction device in the subcritical current regime. The proposed structure consumes low power and occupies a small area. Also, to improve the quality of random numbers production and compensate for the impact of process variations on the quality of the random output, the proposed TRNG includes an internal postprocessing unit. Compared to state-of-the-art designs, using an internal postprocessing unit reduces the proposed generator's area overhead and power consumption. The simulation results show that the TRNG proposed in this letter consumes up to 68% less power and occupies up to 64% smaller area than the state-of-the-art design. Also, due to the existence of the efficient postprocessing unit, the proposed TRNG successfully passes the National Institute of Standards and Technology random number tests even in the presence of the fabrication process variations.
{"title":"Theoretical Circuit Design of an Efficient Spintronic Random Number Generator With an Internal Postprocessing Unit","authors":"Saeed Mehri;Abdolah Amirany;Mohammad Hossein Moaiyeri;Kian Jafari","doi":"10.1109/LMAG.2022.3200326","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3200326","url":null,"abstract":"In this letter, a spintronic true random number generator (TRNG) is designed using the stochastic switching feature of the magnetic tunnel junction device in the subcritical current regime. The proposed structure consumes low power and occupies a small area. Also, to improve the quality of random numbers production and compensate for the impact of process variations on the quality of the random output, the proposed TRNG includes an internal postprocessing unit. Compared to state-of-the-art designs, using an internal postprocessing unit reduces the proposed generator's area overhead and power consumption. The simulation results show that the TRNG proposed in this letter consumes up to 68% less power and occupies up to 64% smaller area than the state-of-the-art design. Also, due to the existence of the efficient postprocessing unit, the proposed TRNG successfully passes the National Institute of Standards and Technology random number tests even in the presence of the fabrication process variations.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67740925","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 : 2022-08-16DOI: 10.1109/LMAG.2022.3199170
Alexander Chizhik;Paula Corte-León;Valentina Zhukova;Julian Gonzalez;Arcady Zhukov
We studied the magneto-optical and magnetic behavior of Co- and Fe-rich microwires that were stress-annealed at temperatures distributed along the microwire length. There was a transformation of the magnetic structure across zones subjected to annealing at different temperatures. Differences in the magnetic behavior between the surface and bulk were observed for both Co- and Fe-rich microwires. The formation and subsequent transformation of a helical magnetic structure were observed, depending on the type of microwire. Annealing at temperatures below 100 °C affected the magnetic system of microwires. This effect is due to a weak but noticeable relaxation of the initial stresses in all parts of the microwire that even occurs in the low temperature range.
{"title":"Longitudinal Transformation of Magnetic Properties in Magnetic Microwires With Graded Magnetic Anisotropy","authors":"Alexander Chizhik;Paula Corte-León;Valentina Zhukova;Julian Gonzalez;Arcady Zhukov","doi":"10.1109/LMAG.2022.3199170","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3199170","url":null,"abstract":"We studied the magneto-optical and magnetic behavior of Co- and Fe-rich microwires that were stress-annealed at temperatures distributed along the microwire length. There was a transformation of the magnetic structure across zones subjected to annealing at different temperatures. Differences in the magnetic behavior between the surface and bulk were observed for both Co- and Fe-rich microwires. The formation and subsequent transformation of a helical magnetic structure were observed, depending on the type of microwire. Annealing at temperatures below 100 °C affected the magnetic system of microwires. This effect is due to a weak but noticeable relaxation of the initial stresses in all parts of the microwire that even occurs in the low temperature range.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741242","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 : 2022-08-16DOI: 10.1109/LMAG.2022.3198370
Mai Lu;Shoogo Ueno
This work investigates the exposure experienced by the nursing staff executing deep transcranial magnetic stimulations (TMS) using H-coil. The safety assessment was implemented by employing the H-coil and realistic human model. The 144 relative positions of the H-coil with respect to the TMS operator body were considered, including the distance and vertical height. Dependence of the magnetic flux density and induced electric fields in the human model were obtained by using the impedance method. Results were compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Regarding the occupational exposure, safe distances of 120 and 100 cm are derived from the ICNIRP reference level (RL) and basic restriction (BR), respectively. At the distance of 100 cm, the exposure level does not exceed the ICNIRP BR, and although the exposure level exceeds the RL, continued exposure is allowed. The findings suggest that nursing staff should stand at least 100 cm apart from the H-coil.
{"title":"Safety Assessment of H-Coil for Nursing Staff in Deep Transcranial Magnetic Stimulation","authors":"Mai Lu;Shoogo Ueno","doi":"10.1109/LMAG.2022.3198370","DOIUrl":"https://doi.org/10.1109/LMAG.2022.3198370","url":null,"abstract":"This work investigates the exposure experienced by the nursing staff executing deep transcranial magnetic stimulations (TMS) using H-coil. The safety assessment was implemented by employing the H-coil and realistic human model. The 144 relative positions of the H-coil with respect to the TMS operator body were considered, including the distance and vertical height. Dependence of the magnetic flux density and induced electric fields in the human model were obtained by using the impedance method. Results were compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Regarding the occupational exposure, safe distances of 120 and 100 cm are derived from the ICNIRP reference level (RL) and basic restriction (BR), respectively. At the distance of 100 cm, the exposure level does not exceed the ICNIRP BR, and although the exposure level exceeds the RL, continued exposure is allowed. The findings suggest that nursing staff should stand at least 100 cm apart from the H-coil.","PeriodicalId":13040,"journal":{"name":"IEEE Magnetics Letters","volume":"13 ","pages":"1-5"},"PeriodicalIF":1.2,"publicationDate":"2022-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://ieeexplore.ieee.org/iel7/5165412/9656771/09857568.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67741202","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}
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