Pub Date : 2024-11-12DOI: 10.1109/TMAG.2024.3496695
Abhishek Chandra;Bram Daniels;Mitrofan Curti;Koen Tiels;Elena A. Lomonova
Hysteresis modeling is crucial to comprehend the behavior of magnetic devices, facilitating optimal designs. Hitherto, deep learning-based methods employed to model hysteresis face challenges in generalizing to novel input magnetic fields. This article addresses the generalization challenge by proposing neural operators for modeling constitutive laws that exhibit magnetic hysteresis by learning a mapping between magnetic fields. In particular, three neural operators—deep operator network (DeepONet), Fourier neural operator (FNO), and wavelet neural operator (WNO)—are employed to predict novel first-order reversal curves and minor loops, where novel means that they are not used to train the model. In addition, a rate-independent FNO is proposed to predict material responses at sampling rates different from those used during training to incorporate the rate-independent characteristics of magnetic hysteresis. The presented numerical experiments demonstrate that neural operators efficiently model magnetic hysteresis, outperforming the traditional neural recurrent methods on various metrics and generalizing to novel magnetic fields. The findings emphasize the advantages of using neural operators for modeling hysteresis under varying magnetic conditions, underscoring their importance in characterizing magnetic material-based devices. The codes related to this article are available at https://github.com/chandratue/magnetic_hysteresis_neural_operator .
{"title":"Magnetic Hysteresis Modeling With Neural Operators","authors":"Abhishek Chandra;Bram Daniels;Mitrofan Curti;Koen Tiels;Elena A. Lomonova","doi":"10.1109/TMAG.2024.3496695","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3496695","url":null,"abstract":"Hysteresis modeling is crucial to comprehend the behavior of magnetic devices, facilitating optimal designs. Hitherto, deep learning-based methods employed to model hysteresis face challenges in generalizing to novel input magnetic fields. This article addresses the generalization challenge by proposing neural operators for modeling constitutive laws that exhibit magnetic hysteresis by learning a mapping between magnetic fields. In particular, three neural operators—deep operator network (DeepONet), Fourier neural operator (FNO), and wavelet neural operator (WNO)—are employed to predict novel first-order reversal curves and minor loops, where novel means that they are not used to train the model. In addition, a rate-independent FNO is proposed to predict material responses at sampling rates different from those used during training to incorporate the rate-independent characteristics of magnetic hysteresis. The presented numerical experiments demonstrate that neural operators efficiently model magnetic hysteresis, outperforming the traditional neural recurrent methods on various metrics and generalizing to novel magnetic fields. The findings emphasize the advantages of using neural operators for modeling hysteresis under varying magnetic conditions, underscoring their importance in characterizing magnetic material-based devices. The codes related to this article are available at \u0000<uri>https://github.com/chandratue/magnetic_hysteresis_neural_operator</uri>\u0000.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-11"},"PeriodicalIF":2.1,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912568","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-11DOI: 10.1109/TMAG.2024.3495025
Meenakshi Sravani;Swapnil Bhuktare
The synchronization behavior of two spin torque nano oscillators (STNOs) with second-order anisotropy, connected via parallel coupling, has been studied in the presence of the thermal field. The second-order anisotropy led to the biasing of the free layer (FL) of both the STNOs in the easy cone regime called the conical FL (CFL). This parallel coupling facilitated frequency and in-phase synchronization between the two STNOs without the need for any external field. The simulation results demonstrating this in-phase synchronization have been supported by analytical theory. Further, the effects of parallel coupling on oscillation parameters, such as frequency, power, and linewidth, have been examined. The variation of the frequency with current and the coupling factor has been derived using the LLGS equation. The study achieved a threefold increase in output power and a reduction in linewidth to the order of kHz, without requiring an external field. These advancements highlight the potential of the device for reliable practical applications.
{"title":"Field-Free Mutual Synchronization of Parallel Coupled Spin Torque Nano Oscillators Using a Free Layer With First- and Second-Order Uniaxial Anisotropy","authors":"Meenakshi Sravani;Swapnil Bhuktare","doi":"10.1109/TMAG.2024.3495025","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3495025","url":null,"abstract":"The synchronization behavior of two spin torque nano oscillators (STNOs) with second-order anisotropy, connected via parallel coupling, has been studied in the presence of the thermal field. The second-order anisotropy led to the biasing of the free layer (FL) of both the STNOs in the easy cone regime called the conical FL (CFL). This parallel coupling facilitated frequency and in-phase synchronization between the two STNOs without the need for any external field. The simulation results demonstrating this in-phase synchronization have been supported by analytical theory. Further, the effects of parallel coupling on oscillation parameters, such as frequency, power, and linewidth, have been examined. The variation of the frequency with current and the coupling factor has been derived using the LLGS equation. The study achieved a threefold increase in output power and a reduction in linewidth to the order of kHz, without requiring an external field. These advancements highlight the potential of the device for reliable practical applications.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-7"},"PeriodicalIF":2.1,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-11DOI: 10.1109/TMAG.2024.3493973
Yan Rongge;Zhao Haokai
Contact resistance voltage drop and back electromotive force generated during armature motion are the important parts of muzzle voltage of augmented rail launchers. An inversion method is proposed to accurately obtain the contact resistance between the armature and the rails and the mutual inductance gradient between the inner and outer rails, whose influence on the motion characteristics of augmented rail launchers is further analyzed. First, muzzle voltage, excitation current, armature velocity, and displacement are measured for the contact resistance calculation. Then, a modified adaptive annealing algorithm is used for the inversion of the contact resistance and mutual inductance gradient. Finally, an electromagnetic-force multi-physical field coupling dynamic numerical model for augmented rail launchers is established. The changes of the electromagnetic thrust and current density with the contact resistance and mutual inductance gradient are analyzed, and the calculated armature velocity is compared with the experimental one to verify the effectiveness of the proposed method.
{"title":"Multi-Physical Field Coupling Dynamic Numerical Modeling for Augmented Rail Launchers","authors":"Yan Rongge;Zhao Haokai","doi":"10.1109/TMAG.2024.3493973","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3493973","url":null,"abstract":"Contact resistance voltage drop and back electromotive force generated during armature motion are the important parts of muzzle voltage of augmented rail launchers. An inversion method is proposed to accurately obtain the contact resistance between the armature and the rails and the mutual inductance gradient between the inner and outer rails, whose influence on the motion characteristics of augmented rail launchers is further analyzed. First, muzzle voltage, excitation current, armature velocity, and displacement are measured for the contact resistance calculation. Then, a modified adaptive annealing algorithm is used for the inversion of the contact resistance and mutual inductance gradient. Finally, an electromagnetic-force multi-physical field coupling dynamic numerical model for augmented rail launchers is established. The changes of the electromagnetic thrust and current density with the contact resistance and mutual inductance gradient are analyzed, and the calculated armature velocity is compared with the experimental one to verify the effectiveness of the proposed method.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 3","pages":"1-4"},"PeriodicalIF":2.1,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143496540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multilaminated thin-film inductors are a key to emerging technology that enables highly integrated, on-chip voltage regulators. The permeability of a magnetic core at high frequency is a key determiner of inductance density. In this article, a multilamination magnetic core made up of alternate CoZrTaB (CZTB) amorphous, uniaxially anisotropic magnetic films and AlN dielectric layers is investigated. The individual films are approximately 200 nm thick, appropriate for operation at over 100 MHz, but the laminated structure and overall thickness of several micrometers mean that analytical methods are impractical for computing demagnetization. Magnetostatic finite element analysis (FEAs) is used to model the magnetic core demagnetization, accounting for various length/width dimensions, magnetic film thicknesses, and dielectric thicknesses. At higher frequencies, the dielectric layers, which are included in the structure to suppress induced eddy currents, allow displacement currents to flowthrough the dielectric layers and lead to increased eddy currents circulating around the overall core structure, thus further increasing loss and reducing permeability. Eddy current FEA simulations, which include the displacement currents and an analytically derived equivalent circuit model (ECM), are used to model the real and imaginary (loss) components of permeability spectra. The work, therefore, determines the combined contributions of both demagnetization effects and eddy displacement currents to the reductions in real permeability and the increase in loss components for thicker multilaminated magnetic cores. Permeameter measurements on fabricated cores, having ten laminations, and with various AlN thicknesses (10, 20, 40, and 60 nm) gave excellent agreement with the predicted effective permeability through the approach of combining the FEA and ECM models, over the 10 MHz to 1 GHz frequency range. It was shown, that at 100 MHz, for multilaminated cores with thin or higher k dielectric layers, displacement-eddy currents are dominant, giving a power loss an order of magnitude higher than would be for magnetically induced eddy currents alone.
{"title":"Determining the Effective Permeability of a Laminated CoZrTaB (CZTB) Film Through Consideration of Demagnetization Effects and Eddy-Displacement Currents","authors":"Ruaidhrí Murphy;Guannan Wei;Ansar Masood;Cian O’Mathúna;Zoran Pavlovic;Paul McCloskey;Séamus O’Driscoll","doi":"10.1109/TMAG.2024.3494675","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3494675","url":null,"abstract":"Multilaminated thin-film inductors are a key to emerging technology that enables highly integrated, on-chip voltage regulators. The permeability of a magnetic core at high frequency is a key determiner of inductance density. In this article, a multilamination magnetic core made up of alternate CoZrTaB (CZTB) amorphous, uniaxially anisotropic magnetic films and AlN dielectric layers is investigated. The individual films are approximately 200 nm thick, appropriate for operation at over 100 MHz, but the laminated structure and overall thickness of several micrometers mean that analytical methods are impractical for computing demagnetization. Magnetostatic finite element analysis (FEAs) is used to model the magnetic core demagnetization, accounting for various length/width dimensions, magnetic film thicknesses, and dielectric thicknesses. At higher frequencies, the dielectric layers, which are included in the structure to suppress induced eddy currents, allow displacement currents to flowthrough the dielectric layers and lead to increased eddy currents circulating around the overall core structure, thus further increasing loss and reducing permeability. Eddy current FEA simulations, which include the displacement currents and an analytically derived equivalent circuit model (ECM), are used to model the real and imaginary (loss) components of permeability spectra. The work, therefore, determines the combined contributions of both demagnetization effects and eddy displacement currents to the reductions in real permeability and the increase in loss components for thicker multilaminated magnetic cores. Permeameter measurements on fabricated cores, having ten laminations, and with various AlN thicknesses (10, 20, 40, and 60 nm) gave excellent agreement with the predicted effective permeability through the approach of combining the FEA and ECM models, over the 10 MHz to 1 GHz frequency range. It was shown, that at 100 MHz, for multilaminated cores with thin or higher k dielectric layers, displacement-eddy currents are dominant, giving a power loss an order of magnitude higher than would be for magnetically induced eddy currents alone.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-10"},"PeriodicalIF":2.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912473","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1109/TMAG.2024.3494534
Kyungseon Cho;Yeongkyo Seo
This article proposes a hybrid spin-complementary metal–oxide–semiconductor (CMOS) logic design based on cascadable spin-torque majority gate (STMG), which allows the implementation of multiple STMG logic stages for very large-scale integration circuits by addressing the cascading and fan-out issues encountered in conventional STMGs. In conventional STMG-based logic circuits, excessive current flow occurs owing to simultaneous majority-gate operation across all stages, which may degrade the reliability of domain walls. In contrast, the cascadable STMG (C-STMG), composed of an STMG device and transistors, enables sequential majority gate operations at only selected stages. Furthermore, C-STMG circuits can be segmented into finer stages, enabling fine-grained pipelining, thereby achieving a higher throughput than conventional STMG. Additionally, this article presents a method for designing a 16-bit full-adder (FA) circuit using C-STMG. After the design and verification of the 16-bit C-STMG FA, 32-bit and 64-bit C-STMG FAs are designed, and all configurations are compared with the corresponding CMOS FAs under the same conditions. The C-STMG FAs achieve over 28% improvement in the energy compared with CMOS FAs. Moreover, the improvement in energy consumption is more significant at smaller activity ratios because C-STMG circuits exhibit almost-zero leakage power consumption owing to their non-volatility. In particular, the 64-bit C-STMG FA achieves 76.8% lower-energy dissipation at activity ratios of 1% compared with the corresponding CMOS FA.
{"title":"Energy-Efficient Hybrid Spin-CMOS Logic Design Based on Cascadable Spin-Torque Majority Gate","authors":"Kyungseon Cho;Yeongkyo Seo","doi":"10.1109/TMAG.2024.3494534","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3494534","url":null,"abstract":"This article proposes a hybrid spin-complementary metal–oxide–semiconductor (CMOS) logic design based on cascadable spin-torque majority gate (STMG), which allows the implementation of multiple STMG logic stages for very large-scale integration circuits by addressing the cascading and fan-out issues encountered in conventional STMGs. In conventional STMG-based logic circuits, excessive current flow occurs owing to simultaneous majority-gate operation across all stages, which may degrade the reliability of domain walls. In contrast, the cascadable STMG (C-STMG), composed of an STMG device and transistors, enables sequential majority gate operations at only selected stages. Furthermore, C-STMG circuits can be segmented into finer stages, enabling fine-grained pipelining, thereby achieving a higher throughput than conventional STMG. Additionally, this article presents a method for designing a 16-bit full-adder (FA) circuit using C-STMG. After the design and verification of the 16-bit C-STMG FA, 32-bit and 64-bit C-STMG FAs are designed, and all configurations are compared with the corresponding CMOS FAs under the same conditions. The C-STMG FAs achieve over 28% improvement in the energy compared with CMOS FAs. Moreover, the improvement in energy consumption is more significant at smaller activity ratios because C-STMG circuits exhibit almost-zero leakage power consumption owing to their non-volatility. In particular, the 64-bit C-STMG FA achieves 76.8% lower-energy dissipation at activity ratios of 1% compared with the corresponding CMOS FA.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912401","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study devised a novel optimization technique for toroidal inductors utilizing a two-step Monte Carlo tree search (MCTS) algorithm. The proposed method integrates a global search based on analytical formulas with a local search involving 3-D finite element analysis (FEA). By employing this approach, the optimal core materials, sizes, number of turns, and windings are determined to enhance efficiency and reduce the overall size of the inductors. The proposed method was applied to optimize inductors in a 6.78 MHz electrically coupled power transfer system. The results of the study demonstrate that the optimized inductor, identified through the proposed method, not only achieved superior efficiency but also minimized computational costs. Subsequent system measurements confirmed that the optimized inductor improved system efficiency by over 1.8% compared with inductors designed through empirical methods.
{"title":"Two-Step Monte Carlo Tree Search for Optimal Design of High-Frequency Toroidal Inductors in Power Electronics Circuits","authors":"Nobuto Misono;Tomoki Hirosawa;Yuki Sato;Hirokazu Matsumoto","doi":"10.1109/TMAG.2024.3493941","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3493941","url":null,"abstract":"This study devised a novel optimization technique for toroidal inductors utilizing a two-step Monte Carlo tree search (MCTS) algorithm. The proposed method integrates a global search based on analytical formulas with a local search involving 3-D finite element analysis (FEA). By employing this approach, the optimal core materials, sizes, number of turns, and windings are determined to enhance efficiency and reduce the overall size of the inductors. The proposed method was applied to optimize inductors in a 6.78 MHz electrically coupled power transfer system. The results of the study demonstrate that the optimized inductor, identified through the proposed method, not only achieved superior efficiency but also minimized computational costs. Subsequent system measurements confirmed that the optimized inductor improved system efficiency by over 1.8% compared with inductors designed through empirical methods.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-5"},"PeriodicalIF":2.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this article, a method for calculating the cogging torque and air-gap flux density of a surface-mounted permanent magnet synchronous machine (SPMSM) is studied. First, a simplified model of the SPMSM is presented for electromagnetic analysis, and the magnetic vector potential is derived using the governing equations based on Maxwell’s equations in a 2-D polar coordinate system. The air-gap flux density is derived using appropriate boundary conditions, and based on analytical solutions, the cogging torque was calculated. The analysis results derived through the proposed method, and the skew of the rotor, the skew angle, and segment that satisfy the optimal cogging torque of SPMSMs are derived. The accuracy of the proposed method is verified through a comparison with the analysis results with the finite element method (FEM).
{"title":"Analytical Study and Experimental Verification of Electromagnetic Vibration Sources and Optimization of Rotor Skew in Surface-Mounted Permanent Magnet Synchronous Machines","authors":"Jun-Won Yang;Tae-Seong Kim;Manh-Dung Nguyen;Yong-Joo Kim;Kyung-Hun Shin;Jang-Young Choi","doi":"10.1109/TMAG.2024.3493943","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3493943","url":null,"abstract":"In this article, a method for calculating the cogging torque and air-gap flux density of a surface-mounted permanent magnet synchronous machine (SPMSM) is studied. First, a simplified model of the SPMSM is presented for electromagnetic analysis, and the magnetic vector potential is derived using the governing equations based on Maxwell’s equations in a 2-D polar coordinate system. The air-gap flux density is derived using appropriate boundary conditions, and based on analytical solutions, the cogging torque was calculated. The analysis results derived through the proposed method, and the skew of the rotor, the skew angle, and segment that satisfy the optimal cogging torque of SPMSMs are derived. The accuracy of the proposed method is verified through a comparison with the analysis results with the finite element method (FEM).","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-4"},"PeriodicalIF":2.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142905788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1109/TMAG.2024.3494027
F. Maspero;O. Koplak;A. Plaza;B. Heinz;F. Kohl;P. Pirro;R. Bertacco
Integration of samarium-cobalt hard magnets on silicon requires buffer/protective layers that can enhance the magnetic properties of the magnet while preserving its structure and chemical composition after post-annealing treatments needed for the formation of the magnetically hard phase. In this work, a comparison of samarium-cobalt films for five different buffer/protective layers, namely, Ti, W, TiW, Ta, and Cr, and two different annealing temperatures, 650 °C and 750 °C, is presented. Depending on materials and annealing temperatures, magnetic properties such as saturation and coercivity of the SmCo film can be finely tuned. We show that coercivity up to 3.65 T or saturation magnetization up to 0.95 T can be reached by proper choice of the relevant process parameters: deposition temperature, material for the buffer/protective layer, and annealing temperature. Such value of coercivity is among the highest found in the literature for thin films of SmCo.
{"title":"Influence of Buffer/Protective Layers on the Structural and Magnetic Properties of SmCo Films on Silicon","authors":"F. Maspero;O. Koplak;A. Plaza;B. Heinz;F. Kohl;P. Pirro;R. Bertacco","doi":"10.1109/TMAG.2024.3494027","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3494027","url":null,"abstract":"Integration of samarium-cobalt hard magnets on silicon requires buffer/protective layers that can enhance the magnetic properties of the magnet while preserving its structure and chemical composition after post-annealing treatments needed for the formation of the magnetically hard phase. In this work, a comparison of samarium-cobalt films for five different buffer/protective layers, namely, Ti, W, TiW, Ta, and Cr, and two different annealing temperatures, 650 °C and 750 °C, is presented. Depending on materials and annealing temperatures, magnetic properties such as saturation and coercivity of the SmCo film can be finely tuned. We show that coercivity up to 3.65 T or saturation magnetization up to 0.95 T can be reached by proper choice of the relevant process parameters: deposition temperature, material for the buffer/protective layer, and annealing temperature. Such value of coercivity is among the highest found in the literature for thin films of SmCo.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-8"},"PeriodicalIF":2.1,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1109/TMAG.2024.3487188
Lai Jiang;Vincent Sokalski
Previous research has shown that an in-plane magnetic field can lead to asymmetric growth of magnetic domains in thin films with interfacial Dzyaloshinskii-Moriya interaction (DMI). Moreover, in some Pt/Co/Ni systems, the growth becomes highly directional and deviates from the longitudinal direction. It has been suggested that this is caused by a non-zero effective magnetic field acting on the domain wall (DW) that drives the DW magnetization away from its static equilibrium configuration during growth. In previous work, a transient steady-state model was applied to thin films with relatively weak interfacial DMI and low damping coefficient that accurately predicted the aforementioned directional growth. In this work, we experimentally tested a range of DMIs by systematically varying the thin-film stacking. Off-axis directional growth was found less pronounced with larger interfacial DMI and Gilbert damping constant experimentally, as imaged via magneto-optical Kerr effect (MOKE) microscopy, which is consistent with the transient model proposed previously. This work contributes to understanding the complexity of asymmetric domain expansion within the creep regime, while also expanding the applicable property range of the transient steady-state model.
{"title":"The Observation of the Role of Damping and Interfacial DMI on Directional Domain Wall Creep","authors":"Lai Jiang;Vincent Sokalski","doi":"10.1109/TMAG.2024.3487188","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3487188","url":null,"abstract":"Previous research has shown that an in-plane magnetic field can lead to asymmetric growth of magnetic domains in thin films with interfacial Dzyaloshinskii-Moriya interaction (DMI). Moreover, in some Pt/Co/Ni systems, the growth becomes highly directional and deviates from the longitudinal direction. It has been suggested that this is caused by a non-zero effective magnetic field acting on the domain wall (DW) that drives the DW magnetization away from its static equilibrium configuration during growth. In previous work, a transient steady-state model was applied to thin films with relatively weak interfacial DMI and low damping coefficient that accurately predicted the aforementioned directional growth. In this work, we experimentally tested a range of DMIs by systematically varying the thin-film stacking. Off-axis directional growth was found less pronounced with larger interfacial DMI and Gilbert damping constant experimentally, as imaged via magneto-optical Kerr effect (MOKE) microscopy, which is consistent with the transient model proposed previously. This work contributes to understanding the complexity of asymmetric domain expansion within the creep regime, while also expanding the applicable property range of the transient steady-state model.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-5"},"PeriodicalIF":2.1,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-04DOI: 10.1109/TMAG.2024.3491573
You Wang;Da Song;Erya Deng;Yefan Xu;Yu Gong;Weiqiang Liu
Spin-transfer torque magnetic random access memory (STT-MRAM) is a promising storage technology due to its low power consumption, great scalability, and high endurance. However, with the downscaling of the technology node, the process variation of the device increases fast, leading to increased read failures and read disturbance in STT-MRAM. Moreover, as STT-MRAM is usually considered as an energy-efficient device for low-power designs, the overscaling of supply voltage further degrades the read yield and read latency. In this article, a novel sensing circuit is proposed to improve read yield and read speed by utilizing a path-switching approach. The simulation results demonstrate a sensing latency of 400 ps at a supply voltage of 1 V, with a read yield of 99.9%. Moreover, the proposed circuit exhibits no degradation in read yield at 100 °C or with the supply voltage as low as 0.6 V, demonstrating high reliability.
{"title":"A High-Speed and High-Yield Path-Switching Sensing Circuit for STT-MRAM","authors":"You Wang;Da Song;Erya Deng;Yefan Xu;Yu Gong;Weiqiang Liu","doi":"10.1109/TMAG.2024.3491573","DOIUrl":"https://doi.org/10.1109/TMAG.2024.3491573","url":null,"abstract":"Spin-transfer torque magnetic random access memory (STT-MRAM) is a promising storage technology due to its low power consumption, great scalability, and high endurance. However, with the downscaling of the technology node, the process variation of the device increases fast, leading to increased read failures and read disturbance in STT-MRAM. Moreover, as STT-MRAM is usually considered as an energy-efficient device for low-power designs, the overscaling of supply voltage further degrades the read yield and read latency. In this article, a novel sensing circuit is proposed to improve read yield and read speed by utilizing a path-switching approach. The simulation results demonstrate a sensing latency of 400 ps at a supply voltage of 1 V, with a read yield of 99.9%. Moreover, the proposed circuit exhibits no degradation in read yield at 100 °C or with the supply voltage as low as 0.6 V, demonstrating high reliability.","PeriodicalId":13405,"journal":{"name":"IEEE Transactions on Magnetics","volume":"61 1","pages":"1-6"},"PeriodicalIF":2.1,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142912402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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