The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-...The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-density magnetic random-access memory due to its ultrafast switching speed and low power consumption.This review systematically explores the generation and switching mechanisms of electron-mediated torques(including both conventional SOTs and orbital torques)and magnon-mediated torques.We discuss key materials that enable these effects:heavy metals,topological insulators,low-crystal-symmetry materials,non-collinear antiferromagnets,and altermagnets for conventional SOTs;3d,4d,and 5d transition metals for orbital torques;and antiferromagnetic insulator Ni O-and multiferroic Bi Fe O_(3)-based sandwich structures for magnon torques.We emphasize that although key components of SOT devices have been demonstrated,numerous promising materials and critical questions regarding their underlying mechanisms remain to be explored.Therefore,this field represents a dynamic and rapidly evolving frontier in spintronics,offering significant potential for advancing next-generation information storage and computational technologies.展开更多
Switched Reluctance Motors(SRMs),outfitted with rugged construction,good speed range,high torque density,and rare earth-free nature that outweigh induction motors(IM)and permanent magnet synchronous motor(PMSM),afford...Switched Reluctance Motors(SRMs),outfitted with rugged construction,good speed range,high torque density,and rare earth-free nature that outweigh induction motors(IM)and permanent magnet synchronous motor(PMSM),afford a broad range of applications in the domain of electric vehicles(EVs).Standard copper magnetic wire and low-carbon steel laminations are used to construct SRMs,which give them high efficiency in the range of 85-95%.Despite SRM's desirable features over traditional motor-speed drives,high torque ripples and radial distortions constrain their deployment in EVs.Precise rotor position is imperative for effective management of the speed and torque of SRMs.This paper provides an illustrative compendium on review of the torque-speed control and ripple mitigation techniques using design enhancements and control methods for SRM drives for EV applications.The various schemes were evaluated on their performance metricsoperational speed range,control complexity,practical realization,need for pre-stored parameters(look-up tables of current,inductance and torque profiles)and motor controller memory requirements.The findings provide valuable insights into balancing the gains and trade-offs associated with EV applications.Furthermore,they pinpoint opportunities for enhancement by analyzing the cost and technical aspects of different SRM controllers.展开更多
Compared to the conventional permanent magnet synchronous machine(PMSM),the main characteristic of permanent magnet torque machine(PMTM)with high torque is that armature current is high,which has a great influence on ...Compared to the conventional permanent magnet synchronous machine(PMSM),the main characteristic of permanent magnet torque machine(PMTM)with high torque is that armature current is high,which has a great influence on magnetic circuit saturation,so this paper proposes a novel analytical method(AM)considering this problem.The key of this new AM is to consider armature reaction flux and armature leakage flux,which are closely related to output torque.Firstly,the expressions,including magnetomotive force(MMF)generated by permanent magnets(PMs)and armature windings are derived,and meanwhile slotting effect is considered by planning flux path.In addition,the expression of leakage flux density generated by armature windings are calculated,and flux density equivalence coefficient of tooth is calculated to be 2/3,which is used to solve the problem of uneven saturation of each tooth.Then,based on main flux factor and leakage flux factor proposed,an improved iteration process is proposed,and by this new process,the flux density of each yoke and tooth can be obtained,which is beneficial to obtain more accurate air-gap flux density and flux linkage.Finally,a prototype of 60-pole 54-slot is fabricated,and the performances of the electric machine,such as back electromotive force(EMF)and output torque,are calculated by this new AM and finite element method(FEM).The results of FEM and experimental test show that this new AM is good enough to calculate the performance of PMTM.展开更多
Geological deformations are generally attributed to compressional, extensional and strike-slip processes. Since the breakup of Gondwana, torque deformation has been responsible for the current configuration of the wes...Geological deformations are generally attributed to compressional, extensional and strike-slip processes. Since the breakup of Gondwana, torque deformation has been responsible for the current configuration of the western coasts of Africa and the eastern shore of South America and the morphotectonic geometry of the rift basins of South America, conditioning the morphostructure of the Andean chain and the current geoforms of the foreland.展开更多
In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant...In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant harmonics.The key of this study is to evaluate the contributions of harmonics on torque and loss,and further determines the harmonics related to them.Based on this,the torque enhancement factor and loss suppression factor are defined based on the selected dominant harmonics.And,the two factors are set as the optimization objectives,aiming at improving the characteristics of torque and loss.At the same time,to achieve an efficient optimization,a layered optimization method is presented,which includes magnet source layer and permeance layer.Based on the optimization,the motor torque is improved effectively,while the rotor iron loss is also reduced significantly.Then,a prototype motor is manufactured for experimental test.Finally,the simulation analysis and test results verify the validation of the studied motor and the proposed optimization method based on dominant harmonics.展开更多
Ferrimagnets are important for next-generation high-density ultrafast spintronic device applications.Magnetization compensation temperature(TM)is a fundamentally critical magnetic parameter for ferrimagnets besides th...Ferrimagnets are important for next-generation high-density ultrafast spintronic device applications.Magnetization compensation temperature(TM)is a fundamentally critical magnetic parameter for ferrimagnets besides their Curie temperature.Around TM,the spin-orbit switching efficiencies are extraordinarily high.Therefore,the accurate manipulation of TM from the material fabrication process is essential for the electrical steering of ferrimagnetic spins.In this work,CoTb thin films,with the 3 d and 4 f magnetic sublattices antiferromagnetically coupled to each other,are deposited at different temperatures.The magnetotransport and magnetic properties of these films are systematically investigated.It was found that the TM of this rare-earth ferrimagnet largely depends on the growth temperature and it can be tuned by over 100 K.Accordingly,the spins of an optimized ferrimagnetic CoTb thin film with its TM close to room temperature can be efficiently switched by the current-pulse-induced spin-orbit torque.Moreover,an artificial neural network utilizing the spin-orbit torque device was constructed,demonstrating an image recognition accuracy of approximately 92.5%,which is comparable to that of conventional software solutions.Thus,this work demonstrates the large tunability of TM of a rare earth ferrimagnet by chemical ordering and the great potential of such a ferrimagnet for electrically operated spintronic devices.展开更多
Joint health is critical for musculoskeletal(MSK)conditions that are affecting approximately one-third of the global population.Monitoring of joint torque can offer an important pathway for the evaluation of joint hea...Joint health is critical for musculoskeletal(MSK)conditions that are affecting approximately one-third of the global population.Monitoring of joint torque can offer an important pathway for the evaluation of joint health and guided intervention.However,there is no technology that can provide the precision,effectiveness,low-resource setting,and longterm wearability to simultaneously achieve both rapid and accurate joint torque measurement to enable risk assessment of joint injury and long-term monitoring of joint rehabilitation in wider environments.Herein,we propose a piezoelectric boron nitride nanotubes(BNNTs)-based,AI-enabled wearable device for regular monitoring of joint torque.We first adopted an iterative inverse design to fabricate the wearable materials with a Poisson's ratio precisely matched to knee biomechanics.A highly sensitive piezoelectric film was constructed based on BNNTs and polydimethylsiloxane and applied to precisely capture the knee motion,while concurrently realizing self-sufficient energy harvesting.With the help of a lightweight on-device artificial neural network,the proposed wearable device was capable of accurately extracting targeted signals from the complex piezoelectric outputs and then effectively mapping these signals to their corresponding physical characteristics,including torque,angle,and loading.A real-time platform was constructed to demonstrate the capability of fine real-time torque estimation.This work offers a relatively low-cost wearable solution for effective,regular joint torque monitoring that can be made accessible to diverse populations in countries and regions with heterogeneous development levels,potentially producing wide-reaching global implications for joint health,MSK conditions,ageing,rehabilitation,personal health,and beyond.展开更多
The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contribu...The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contributions. In multilayer systems, extrinsic interfacial scattering, along with scattering from defects or impurities inside the materials, plays a crucial role in affecting the SOT efficiency. In this study, we successfully fabricated high-quality epitaxially grown [Ir/Pt]N superlattices with an increasing number of interfaces using a magnetron sputtering system to investigate the contribution of extrinsic interfacial scattering to SOT efficiency. We measured SOT efficiency through spin-torque ferromagnetic resonance methods and determined the spin Hall angle using the spin pumping technique. Additionally, we calculated spin transparency based on the SOT efficiency and spin Hall angle. Our findings indicate that the values of SOT efficiency, spin Hall angle, and spin transparency are enhanced in the superlattice structure compared to Pt, which we attribute to the increase in interfacial scattering.This research offers an effective strategy for designing and fabricating advanced spintronic devices.展开更多
The digital twin,as the decision center of the automated drilling system,incorporates physical or data-driven models to predict the system response(rate of penetration,down-hole circulating pressure,drilling torques,e...The digital twin,as the decision center of the automated drilling system,incorporates physical or data-driven models to predict the system response(rate of penetration,down-hole circulating pressure,drilling torques,etc.).Real-time drilling torque prediction aids in drilling parameter optimization,drill string stabilization,and comparing the discrepancy between observed signal and theoretical trend to detect down-hole anomalies.Due to their inability to handle huge amounts of time series data,current machine learning techniques are unsuitable for the online prediction of drilling torque.Therefore,a new way,the just-in-time learning(JITL)framework and local machine learning model,are proposed to solve the problem.The steps in this method are:(1)a specific metric is designed to measure the similarity between time series drilling data and scenarios to be predicted ahead of bit;(2)parts of drilling data are selected to train a local model for a specific prediction scenario separately;(3)the local machine learning model is used to predict drilling torque ahead of bit.Both the model data test results and the field data application results certify the advantages of the method over the traditional sliding window methods.Moreover,the proposed method has been proven to be effective in drilling parameter optimization and pipe sticking trend detection.Finally,we offer suggestions for the selection of local machine learning algorithms and real-time prediction with this approach based on the test results.展开更多
Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms ...Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.展开更多
In-memory computing(IMC)based on spin-logic devices is regarded as an advantageous way to optimize the Von Neumann bottleneck.However,performing complete Boolean logic with spintronic devices typi-cally requires an in...In-memory computing(IMC)based on spin-logic devices is regarded as an advantageous way to optimize the Von Neumann bottleneck.However,performing complete Boolean logic with spintronic devices typi-cally requires an initialization operation,which can reduce processing speed.In this work,we conceptu-alize and experimentally demonstrate a programmable and initialization-free spin-logic gate,leveraging spin-orbit torque(SOT)to effectuate magnetization switching,assisted by in-plane Oersted field gener-ated by an integrated bias-field Au line.This spin-logic gate,fabricated as a Hall bar,allows complete Boolean logic operations without initialization.A current flowing through the bias-field line,which is electrically isolated from the device by a dielectric,generates an in-plane magnetic field that can invert the SOT-induced switching chirality,enabling on-the-fly complete Boolean logic operations.Additionally,the device demonstrated good reliability,repeatability,and reproducibility during logic operations.Our work demonstrates programmable and scalable spin-logic functions in a single device,offering a new approach for spin-logic operations in an IMC architecture.展开更多
The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-per...The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.展开更多
We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128...We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128∘Y-LiNbO_(3) substrate exhibits uniform out-of-plane spin angular momentum.This acoustic spin triggers the DW motion at a velocity exceeding 50 m/s in a way that is similar to the spin-transfer-torque effect.This phenomenon highlights the potential of acoustic spin in enabling rapid DW displacement,offering an innovative approach to developing energy-efficient spintronic devices.展开更多
Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic ...Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.展开更多
Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),i...Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),in particular the resonant portion,is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER.While the electromagnetic torque always opposes the plasma flow,the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction.A peculiar double-peak structure for the net NTV torque is robustly computed for ITER,as the toroidal rotation frequency is scanned near the zero value.This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral(over the particle pitch angle)in the superbanana plateau NTV regime in ITER.These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity,the plasma pedestal flow and the assumed frequency of the rotating RMP field.展开更多
To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delaye...To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delayed to reduce transmission output shaft torque during gear shift. In contrast to traditional control method, the closed loop control system based on torque observer can obviously reduce the transmission output shaft torque during gear shift. It can be concluded that by way of torque feedback closed loop control, transmission shift shock can be reduced.展开更多
Permanent magnet assisted synchronous reluctance motor(PMA-SynRM)is a kind of high torque density energy conversion device widely used in modern industry.In this paper,based on the basic topology of PMA-SynRM,a novel ...Permanent magnet assisted synchronous reluctance motor(PMA-SynRM)is a kind of high torque density energy conversion device widely used in modern industry.In this paper,based on the basic topology of PMA-SynRM,a novel PMA-SynRM of asymmetric rotor with position-biased magnet is proposed.The asymmetric rotor design with position-biased magnet realizes the concentration of magnetic field lines in the motor air gap to obtain higher electromagnetic torque,and makes both of magnetic and reluctance torque obtain the peak value at the same current phase angle.The asymmetric rotor configuration is theoretically illustrated by space vector diagram,and the feasibility of high torque performance of the motor is verified.Through the finite element simulation,the effect of the side barrier on output torque and the Mises stress under the rotor asymmetrical design are analyzed.Then the motor characteristics including airgap flux density,back EMF,magnetic torque,reluctance torque,torque ripple,losses,and efficiency are calculated for both the basic and proposed PMA-SynRMs.The results show that the proposed PMA-SynRM has higher torque and efficiency than the basic topology.Moreover,the torque ripple of the proposed PMA-SynRM is reduced by the method with harmonic current injection,and the torque characteristics in the whole current cycle are analyzed.Finally,the endurance to avoid PM demagnetization is confirmed based on the PM remanence calculation.展开更多
We study inserting Co layer thickness-dependent spin transport and spin-orbit torques(SOTs)in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance.The interfacial perpendicular magnetic anisotropy(IPMA)energy...We study inserting Co layer thickness-dependent spin transport and spin-orbit torques(SOTs)in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance.The interfacial perpendicular magnetic anisotropy(IPMA)energy density(Ks=2.7 erg/cm^(2),1 erg=10^(-7) J),which is dominated by interfacial spin-orbit coupling(ISOC)in the Pt/Co interface,total effective spin-mixing conductance(G↑↓eff,tot=0.42×10^(15) Ω^(-1)·m^(-2))and two-magnon scattering(βTMS=0.46 nm2)are first characterized,and the damping-like torque(ξDL=0.103)and field-like torque(ξFL=-0.017)efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer.The significant enhancement of ξDL and ξFL in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface.Additionally,we find a considerable out-of-plane spin polarization SOT,which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface.Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation.Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface.展开更多
Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosys...Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosystems.This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output torque.Firstly,the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed.Secondly,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM.Then,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in CTR.Meanwhile,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation.Finally,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.U24A6002,12174237(X.X.),52471253(F.W.),12404091(J.L.),52171183(Z.Q.))the support from the National Key Research and Development Program of China(Grant No.2022YFB3505301)+4 种基金the support from the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Province(Grant No.20240019)Central Government’s Special Fund for Local Science and Technology Development(Grant No.YDZJSX2024D058)the support from the Basic Research Plan of Shanxi Province(Grant No.202403021212016)the support from the Fundamental Research Program of Shanxi Province(Grant No.202403021222252)the Higher Education Science and Technology Innovation Plan Project of Shanxi(Grant No.2024L146)。
文摘The growing demand for artificial intelligence and complex computing has underscored the urgent need for advanced data storage technologies.Spin-orbit torque(SOT)has emerged as a leading candidate for high-speed,high-density magnetic random-access memory due to its ultrafast switching speed and low power consumption.This review systematically explores the generation and switching mechanisms of electron-mediated torques(including both conventional SOTs and orbital torques)and magnon-mediated torques.We discuss key materials that enable these effects:heavy metals,topological insulators,low-crystal-symmetry materials,non-collinear antiferromagnets,and altermagnets for conventional SOTs;3d,4d,and 5d transition metals for orbital torques;and antiferromagnetic insulator Ni O-and multiferroic Bi Fe O_(3)-based sandwich structures for magnon torques.We emphasize that although key components of SOT devices have been demonstrated,numerous promising materials and critical questions regarding their underlying mechanisms remain to be explored.Therefore,this field represents a dynamic and rapidly evolving frontier in spintronics,offering significant potential for advancing next-generation information storage and computational technologies.
基金supported in part by the Universitat Politècnica de València under grant PAID-10-21supported through AMRITA Seed Grant(Proposal ID:ASG2022188)。
文摘Switched Reluctance Motors(SRMs),outfitted with rugged construction,good speed range,high torque density,and rare earth-free nature that outweigh induction motors(IM)and permanent magnet synchronous motor(PMSM),afford a broad range of applications in the domain of electric vehicles(EVs).Standard copper magnetic wire and low-carbon steel laminations are used to construct SRMs,which give them high efficiency in the range of 85-95%.Despite SRM's desirable features over traditional motor-speed drives,high torque ripples and radial distortions constrain their deployment in EVs.Precise rotor position is imperative for effective management of the speed and torque of SRMs.This paper provides an illustrative compendium on review of the torque-speed control and ripple mitigation techniques using design enhancements and control methods for SRM drives for EV applications.The various schemes were evaluated on their performance metricsoperational speed range,control complexity,practical realization,need for pre-stored parameters(look-up tables of current,inductance and torque profiles)and motor controller memory requirements.The findings provide valuable insights into balancing the gains and trade-offs associated with EV applications.Furthermore,they pinpoint opportunities for enhancement by analyzing the cost and technical aspects of different SRM controllers.
基金supported in part by the National Natural Science Foundation of China under Grant 52125701.
文摘Compared to the conventional permanent magnet synchronous machine(PMSM),the main characteristic of permanent magnet torque machine(PMTM)with high torque is that armature current is high,which has a great influence on magnetic circuit saturation,so this paper proposes a novel analytical method(AM)considering this problem.The key of this new AM is to consider armature reaction flux and armature leakage flux,which are closely related to output torque.Firstly,the expressions,including magnetomotive force(MMF)generated by permanent magnets(PMs)and armature windings are derived,and meanwhile slotting effect is considered by planning flux path.In addition,the expression of leakage flux density generated by armature windings are calculated,and flux density equivalence coefficient of tooth is calculated to be 2/3,which is used to solve the problem of uneven saturation of each tooth.Then,based on main flux factor and leakage flux factor proposed,an improved iteration process is proposed,and by this new process,the flux density of each yoke and tooth can be obtained,which is beneficial to obtain more accurate air-gap flux density and flux linkage.Finally,a prototype of 60-pole 54-slot is fabricated,and the performances of the electric machine,such as back electromotive force(EMF)and output torque,are calculated by this new AM and finite element method(FEM).The results of FEM and experimental test show that this new AM is good enough to calculate the performance of PMTM.
文摘Geological deformations are generally attributed to compressional, extensional and strike-slip processes. Since the breakup of Gondwana, torque deformation has been responsible for the current configuration of the western coasts of Africa and the eastern shore of South America and the morphotectonic geometry of the rift basins of South America, conditioning the morphostructure of the Andean chain and the current geoforms of the foreland.
文摘In this paper,a 12/14-pole permanent magnet in-wheel motor is studied for potential in-wheel application,and the torque and loss are improved simultaneously based on designing and optimizing the corresponding dominant harmonics.The key of this study is to evaluate the contributions of harmonics on torque and loss,and further determines the harmonics related to them.Based on this,the torque enhancement factor and loss suppression factor are defined based on the selected dominant harmonics.And,the two factors are set as the optimization objectives,aiming at improving the characteristics of torque and loss.At the same time,to achieve an efficient optimization,a layered optimization method is presented,which includes magnet source layer and permeance layer.Based on the optimization,the motor torque is improved effectively,while the rotor iron loss is also reduced significantly.Then,a prototype motor is manufactured for experimental test.Finally,the simulation analysis and test results verify the validation of the studied motor and the proposed optimization method based on dominant harmonics.
基金financial support from the National Key R&D Program of China(Nos.2022YFB3506000 and 2022YFA1602700)financial support from Fundamental Research Funds for the Central Universities+6 种基金financial support from the National Natural Science Foundation of China(Nos.52425106,52121001,and 52271235)financial support from the Beijing Natural Science Foundation(No.JQ23005)financial support from the National Natural Science Foundation of China(No.52401300)funding from the China National Postdoctoral Program for Innovative Talents(No.BX20230451)from the China Postdoctoral Science Foundation(No.2024M754058)financial support from the National Natural Science Foundation of China(No.62401276)financial support from the National Natural Science Foundation of China(No.524B2003).
文摘Ferrimagnets are important for next-generation high-density ultrafast spintronic device applications.Magnetization compensation temperature(TM)is a fundamentally critical magnetic parameter for ferrimagnets besides their Curie temperature.Around TM,the spin-orbit switching efficiencies are extraordinarily high.Therefore,the accurate manipulation of TM from the material fabrication process is essential for the electrical steering of ferrimagnetic spins.In this work,CoTb thin films,with the 3 d and 4 f magnetic sublattices antiferromagnetically coupled to each other,are deposited at different temperatures.The magnetotransport and magnetic properties of these films are systematically investigated.It was found that the TM of this rare-earth ferrimagnet largely depends on the growth temperature and it can be tuned by over 100 K.Accordingly,the spins of an optimized ferrimagnetic CoTb thin film with its TM close to room temperature can be efficiently switched by the current-pulse-induced spin-orbit torque.Moreover,an artificial neural network utilizing the spin-orbit torque device was constructed,demonstrating an image recognition accuracy of approximately 92.5%,which is comparable to that of conventional software solutions.Thus,this work demonstrates the large tunability of TM of a rare earth ferrimagnet by chemical ordering and the great potential of such a ferrimagnet for electrically operated spintronic devices.
基金support from the EPSRC REMIN project(EP/W009412/1)the UCL Fellowship Incubator Award+6 种基金the EPSRC award(TEGMOF EP/Z534146/1)for fundingfinancial support from the China Scholarship Councilfinancial support from UCL Research Excellence Scholarshipthe Wellcome Trust and EPSRC through the WEISS Centre(grant:203145Z/16/Z)at UCLsupport from the Royal Society Research Grant(RGSR2222333)Engineering and Physical Sciences Research Council Grant(13171178 R00287)European Innovative Council(EIC)under the European Union’s Horizon Europe research and innovation program(Grant agreement No.101099093)。
文摘Joint health is critical for musculoskeletal(MSK)conditions that are affecting approximately one-third of the global population.Monitoring of joint torque can offer an important pathway for the evaluation of joint health and guided intervention.However,there is no technology that can provide the precision,effectiveness,low-resource setting,and longterm wearability to simultaneously achieve both rapid and accurate joint torque measurement to enable risk assessment of joint injury and long-term monitoring of joint rehabilitation in wider environments.Herein,we propose a piezoelectric boron nitride nanotubes(BNNTs)-based,AI-enabled wearable device for regular monitoring of joint torque.We first adopted an iterative inverse design to fabricate the wearable materials with a Poisson's ratio precisely matched to knee biomechanics.A highly sensitive piezoelectric film was constructed based on BNNTs and polydimethylsiloxane and applied to precisely capture the knee motion,while concurrently realizing self-sufficient energy harvesting.With the help of a lightweight on-device artificial neural network,the proposed wearable device was capable of accurately extracting targeted signals from the complex piezoelectric outputs and then effectively mapping these signals to their corresponding physical characteristics,including torque,angle,and loading.A real-time platform was constructed to demonstrate the capability of fine real-time torque estimation.This work offers a relatively low-cost wearable solution for effective,regular joint torque monitoring that can be made accessible to diverse populations in countries and regions with heterogeneous development levels,potentially producing wide-reaching global implications for joint health,MSK conditions,ageing,rehabilitation,personal health,and beyond.
基金financially supported by the Science Center of the National Science Foundation of China (Grant No. 52088101)the National Natural Science Foundation of China (Grant Nos. 52161160334, 12274437, 12174426, and 52271237)+1 种基金the Chinese Academy of Sciences (CAS) Project for Young Scientists in Basic Research No. YSBR-084the CAS Youth Interdisciplinary Team。
文摘The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contributions. In multilayer systems, extrinsic interfacial scattering, along with scattering from defects or impurities inside the materials, plays a crucial role in affecting the SOT efficiency. In this study, we successfully fabricated high-quality epitaxially grown [Ir/Pt]N superlattices with an increasing number of interfaces using a magnetron sputtering system to investigate the contribution of extrinsic interfacial scattering to SOT efficiency. We measured SOT efficiency through spin-torque ferromagnetic resonance methods and determined the spin Hall angle using the spin pumping technique. Additionally, we calculated spin transparency based on the SOT efficiency and spin Hall angle. Our findings indicate that the values of SOT efficiency, spin Hall angle, and spin transparency are enhanced in the superlattice structure compared to Pt, which we attribute to the increase in interfacial scattering.This research offers an effective strategy for designing and fabricating advanced spintronic devices.
基金support from the Natural Science Foundation of China(Grant numbers:U23B6010 and 52122401).
文摘The digital twin,as the decision center of the automated drilling system,incorporates physical or data-driven models to predict the system response(rate of penetration,down-hole circulating pressure,drilling torques,etc.).Real-time drilling torque prediction aids in drilling parameter optimization,drill string stabilization,and comparing the discrepancy between observed signal and theoretical trend to detect down-hole anomalies.Due to their inability to handle huge amounts of time series data,current machine learning techniques are unsuitable for the online prediction of drilling torque.Therefore,a new way,the just-in-time learning(JITL)framework and local machine learning model,are proposed to solve the problem.The steps in this method are:(1)a specific metric is designed to measure the similarity between time series drilling data and scenarios to be predicted ahead of bit;(2)parts of drilling data are selected to train a local model for a specific prediction scenario separately;(3)the local machine learning model is used to predict drilling torque ahead of bit.Both the model data test results and the field data application results certify the advantages of the method over the traditional sliding window methods.Moreover,the proposed method has been proven to be effective in drilling parameter optimization and pipe sticking trend detection.Finally,we offer suggestions for the selection of local machine learning algorithms and real-time prediction with this approach based on the test results.
基金supported by the Scientific Research Innovation Capability Support Project for Young Faculty (Grant No.ZYGXQNJSKYCXNLZCXMI3)the National Key Research and Development Program of China (Grant No.2022YFA1604402)+1 种基金the National Natural Science Foundation of China (Grant Nos.U23A6002,92250307,and 52225106)the Beijing Municipal Science and Technology Commission,Administrative Commission of Zhongguancun Science Park (Grant No.Z25110000692500)。
文摘Strong-field terahertz(THz) radiation holds significant potential in non-equilibrium state manipulation, electron acceleration, and biomedical effects. However, distortion-free detection of strong-field THz waveforms remains an essential challenge in THz science and technology. To address this issue, we propose a ferromagnetic detection scheme based on Zeeman torque sampling, achieving distortion-free strong-field THz waveform detection in Py films. Thickness-dependent characterization(3–21 nm) identifies peak detection performance at 21 nm within the investigated range. Furthermore, by structurally engineering the Py ferromagnetic layer, we demonstrate strong-field THz detection in symmetric Ta(3 nm)/Py(9 nm)/Ta(3 nm) heterostructure while simultaneously resolving Zeeman torque responses and collective spin-wave dynamics in asymmetric W(4 nm)/Py(9 nm)/Pt(2 nm)heterostructure. We calculated spin wave excitations and spin orbit torque distributions in asymmetric heterostructures, along with spin wave excitations in symmetric modes. This approach overcomes the sensitivity limitations of conventional techniques in strong-field conditions.
基金supported by the National Science and Technology Major Project(2020AAA0109005)the National Natural Science Foundation of China(62374055,12327806,62304083,62074063,61821003,61904060,61904051,61674062)+4 种基金the Interdisciplinary Program of Wuhan National High Magnetic Field Center(WHMFC202119)the Shenzhen Science and Technology Program Award(JCYJ20220818103410022)the Shenzhen Virtual University Park(2021Szvup091)the Natural Science Foundation of Wuhan(2024040701010049)Shuai Zhang acknowledges support from the China Postdoctoral Science Foundation(2022M721237).
文摘In-memory computing(IMC)based on spin-logic devices is regarded as an advantageous way to optimize the Von Neumann bottleneck.However,performing complete Boolean logic with spintronic devices typi-cally requires an initialization operation,which can reduce processing speed.In this work,we conceptu-alize and experimentally demonstrate a programmable and initialization-free spin-logic gate,leveraging spin-orbit torque(SOT)to effectuate magnetization switching,assisted by in-plane Oersted field gener-ated by an integrated bias-field Au line.This spin-logic gate,fabricated as a Hall bar,allows complete Boolean logic operations without initialization.A current flowing through the bias-field line,which is electrically isolated from the device by a dielectric,generates an in-plane magnetic field that can invert the SOT-induced switching chirality,enabling on-the-fly complete Boolean logic operations.Additionally,the device demonstrated good reliability,repeatability,and reproducibility during logic operations.Our work demonstrates programmable and scalable spin-logic functions in a single device,offering a new approach for spin-logic operations in an IMC architecture.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1204000)the Beijing National Natural Science Foundation(Grant No.Z230006)the National Natural Science Foundation of China(Grant Nos.12304155 and 12274405).
文摘The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0103300)the open research fund of Songshan Lake Materials Laboratory(Grant No.2023SLABFN26)the Natural Science Foundation of Hubei Province(Grant No.2022CFA088)。
文摘We predict high-velocity magnetic domain wall(DW)motion driven by out-of-plane acoustic spin in surface acoustic waves(SAWs).We demonstrate that the SAW propagating at a 30-degree angle relative to the x-axis of a 128∘Y-LiNbO_(3) substrate exhibits uniform out-of-plane spin angular momentum.This acoustic spin triggers the DW motion at a velocity exceeding 50 m/s in a way that is similar to the spin-transfer-torque effect.This phenomenon highlights the potential of acoustic spin in enabling rapid DW displacement,offering an innovative approach to developing energy-efficient spintronic devices.
基金Project supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C01053)the Key Research and Development Program of Zhejiang Province(Grant No.2021C01039)+1 种基金the National Natural Science Foundation of China(Grant No.62293493)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ21A050001)。
文摘Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.
基金funded by National Natural Science Foundation of China(NSFC)(Nos.12075053,11505021 and 11975068)by National Key R&D Program of China(No.2022YFE 03060002)+1 种基金by Fundamental Research Funds for the Central Universities(No.2232024G-10)supported by the U.S.DoE Office of Science(No.DE-FG02–95ER54309)。
文摘Toroidal torques,generated by the resonant magnetic perturbation(RMP)and acting on the plasma column,are numerically systematically investigated for an ITER baseline scenario.The neoclassical toroidal viscosity(NTV),in particular the resonant portion,is found to provide the dominant contribution to the total toroidal torque under the slow plasma flow regime in ITER.While the electromagnetic torque always opposes the plasma flow,the toroidal torque associated with the Reynolds stress enhances the plasma flow independent of the flow direction.A peculiar double-peak structure for the net NTV torque is robustly computed for ITER,as the toroidal rotation frequency is scanned near the zero value.This structure is found to be ultimately due to a non-monotonic behavior of the wave-particle resonance integral(over the particle pitch angle)in the superbanana plateau NTV regime in ITER.These findings are qualitatively insensitive to variations of a range of factors including the wall resistivity,the plasma pedestal flow and the assumed frequency of the rotating RMP field.
文摘To reduce shock during transmission gear shift, a transmission torque feedback closed loop control system is proposed based on the powertrain system model and a torque observer. The ignition time of engine was delayed to reduce transmission output shaft torque during gear shift. In contrast to traditional control method, the closed loop control system based on torque observer can obviously reduce the transmission output shaft torque during gear shift. It can be concluded that by way of torque feedback closed loop control, transmission shift shock can be reduced.
基金supported in part by the National Natural Science Foundation of China under Grant 52077123 and 51737008in part by the Natural Science Foundation of Shandong Province of China for Outstanding Young Scholars,under Grant ZR2021YQ35。
文摘Permanent magnet assisted synchronous reluctance motor(PMA-SynRM)is a kind of high torque density energy conversion device widely used in modern industry.In this paper,based on the basic topology of PMA-SynRM,a novel PMA-SynRM of asymmetric rotor with position-biased magnet is proposed.The asymmetric rotor design with position-biased magnet realizes the concentration of magnetic field lines in the motor air gap to obtain higher electromagnetic torque,and makes both of magnetic and reluctance torque obtain the peak value at the same current phase angle.The asymmetric rotor configuration is theoretically illustrated by space vector diagram,and the feasibility of high torque performance of the motor is verified.Through the finite element simulation,the effect of the side barrier on output torque and the Mises stress under the rotor asymmetrical design are analyzed.Then the motor characteristics including airgap flux density,back EMF,magnetic torque,reluctance torque,torque ripple,losses,and efficiency are calculated for both the basic and proposed PMA-SynRMs.The results show that the proposed PMA-SynRM has higher torque and efficiency than the basic topology.Moreover,the torque ripple of the proposed PMA-SynRM is reduced by the method with harmonic current injection,and the torque characteristics in the whole current cycle are analyzed.Finally,the endurance to avoid PM demagnetization is confirmed based on the PM remanence calculation.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11774150,12074178,11874135,and 12004171)the Applied Basic Research Programs of the Science and Technology Commission Foundation of Jiangsu Province,China(Grant No.BK20200309)+1 种基金the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology,Key Research and Development Program of Zhejiang Province,China(Grant No.2021C01039)the Scientific Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY220164).
文摘We study inserting Co layer thickness-dependent spin transport and spin-orbit torques(SOTs)in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance.The interfacial perpendicular magnetic anisotropy(IPMA)energy density(Ks=2.7 erg/cm^(2),1 erg=10^(-7) J),which is dominated by interfacial spin-orbit coupling(ISOC)in the Pt/Co interface,total effective spin-mixing conductance(G↑↓eff,tot=0.42×10^(15) Ω^(-1)·m^(-2))and two-magnon scattering(βTMS=0.46 nm2)are first characterized,and the damping-like torque(ξDL=0.103)and field-like torque(ξFL=-0.017)efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer.The significant enhancement of ξDL and ξFL in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface.Additionally,we find a considerable out-of-plane spin polarization SOT,which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface.Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation.Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface.
基金supported in part by the National Nature Science Foundation of China(NSFC)under Project 52122705。
文摘Better torque performance and higher reliability have long been the focus of research for slotted limited-angle torque motors(LATMs),which are primarily used to position first-stage valves in electrohydraulic servosystems.This paper presents a high reliability axial-flux slotted LATM with quasi-Halbach array for torque performance improvement including constant torque range(CTR)and output torque.Firstly,the structure with two sets of windings and the operation principle of the proposed slotted LATM is analyzed.Secondly,a brief design procedure is presented,the structure selections of open slot and double-stator single-rotor(DSSR)interior rotor with surface mounted quasi-Halbach permanent magnet(PM)array are illustrated,and the geometric parameters are optimized to obtain the optimal design of the proposed slotted LATM.Then,3-D finite-element method(FEM)is employed to compare the proposed slotted LATM with the conventional surface mounted PM slotted LATM in terms of cogging torque,no-load back EMF,and output torque,and the results show that the proposed LATM with quasi-Halbach array has a 10%improvement in output torque and a 25%improvement in CTR.Meanwhile,the flux linkages and torque performance of the two sets of windings under various conditions verify good magnetic isolation.Finally,prototypes of two different rotor types are manufactured and a series of experiments are performed to validate the analysis.
