We review our recent works on dynamics of magnetization in ferromagnet with spin-transfer torque. Driven by constant spin-polarized current, the spin-transfer torque counteracts both the precession driven by the effec...We review our recent works on dynamics of magnetization in ferromagnet with spin-transfer torque. Driven by constant spin-polarized current, the spin-transfer torque counteracts both the precession driven by the effective field and the Gilbert damping term different from the common understanding. When the spin current exceeds the critical value, the conjunctive action of Gilbert damping and spin-transfer torque leads naturally the novel screw-pitch effect characterized by the temporal oscillation of domain wall velocity and width. Driven by space- and time-dependent spin-polarized current and magnetic field, we expatiate the formation of domain wall velocity in ferromagnetic nanowire. We discuss the properties of dynamic magnetic soliton in uniaxial anisotropic ferromagnetic nanowire driven by spin-transfer torque, and analyze the modulation instability and dark soliton on the spin wave background, which shows the characteristic breather behavior of the soliton as it propagates along the ferromagnetic nanowire. With stronger breather character, we get the novel magnetic rogue wave and clarify its formation mechanism. The generation of magnetic rogue wave mainly arises from the accumulation of energy and magnons toward to its central part. We also observe that the spin-polarized current can control the exchange rate of magnons between the envelope soliton and the background, and the critical current condition is obtained analytically. At last, we have theoretically investigated the current-excited and frequency-adjusted ferromagnetic resonance in magnetic trilayers. A particular case of the perpendicular analyzer reveals that the ferromagnetic resonance curves, including the resonant location and the resonant linewidth, can be adjusted by changing the pinned magnetization direction and the direct current. Under the control of the current and external magnetic field, several magnetic states, such as quasi-parallel and quasi-antiparallel stable states, out-of-plane precession, and bistable states can be realized. The precession frequency can be expressed as a function of the current and external magnetic field.展开更多
The spin-transfer nano-oscillator （STNO） has recently acquired a huge amount of research interest, due to its promising easy tunability along with the miniature size. The output frequency control of an STNO through ...The spin-transfer nano-oscillator （STNO） has recently acquired a huge amount of research interest, due to its promising easy tunability along with the miniature size. The output frequency control of an STNO through magnetic field and current has been examined almost to its full extent; however, there are issues that still need to be addressed. Here, we propose a novel way of voltage control of the output frequency of an STNO, and alongside reducing its power requirement.展开更多
Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access ...Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access memory(MRAM) and spintorque oscillators.We review the fundamental mechanism and experimental progress of the STT effect.Then,different formula of STT torque has been classified,which can be added to the conventional Landau-Lifshitz-Gilbert equation.After that,we show some simulation results that mainly concern the STT-driven vortex dynamics,magnetization oscillations excited by a perpendicular polarizer,and the detail dynamics by in-plane and out-of-plane dual spin polarizers.展开更多
电子自旋属性的自旋电子器件,由于其低能耗、高效率和强稳定性等特点,在磁性存储和计算技术的发展中发挥了重大作用。而如何以一种高能效、确定性和可扩展的方式对作为信息载体的磁性进行操控,这个重要问题在自旋电子学领域引起了利用...电子自旋属性的自旋电子器件,由于其低能耗、高效率和强稳定性等特点,在磁性存储和计算技术的发展中发挥了重大作用。而如何以一种高能效、确定性和可扩展的方式对作为信息载体的磁性进行操控,这个重要问题在自旋电子学领域引起了利用电流操控磁化翻转的广泛研究。本文综述了利用自旋极化电流和纯自旋流操控磁化翻转的研究背景、重要工作和最新进展,详细介绍了自旋转移矩(spin transfer torque,STT)和自旋轨道矩(spinorbit torque,SOT)的产生和作用机制,重点阐述了利用SOT驱动磁畴壁运动和垂直磁化翻转,以及无外磁场磁化翻转的原理。最后探讨了SOT在人工合成反铁磁(synthetic antiferromagnet,SAF)结构中驱动的磁化翻转,为人工合成反铁磁体作为磁性随机访问存储器(magnetic random access memory,MRAM)的应用提供了重要基础,同时也为纯电流操控的自旋电子存储器件相关研究提供了有价值的参考。展开更多
基金supported by the Natural Science Foundation of Hebei Province of China(Grant No.A2012202022)supported by the Aid Program for Young Teachers of Hunan University,the Project-sponsored by SRF for ROCS,SEM+2 种基金the Aid Program for Science and Technology Innovative Research Team in Higher Educational Institution of Hunan Province,Chinasupported by the National Basic Research Program of China(Grant Nos.2011CB921502 and 2012CB821305)the National Natural Science Foundation of China(Grant Nos.61227902 and 61378017)
文摘We review our recent works on dynamics of magnetization in ferromagnet with spin-transfer torque. Driven by constant spin-polarized current, the spin-transfer torque counteracts both the precession driven by the effective field and the Gilbert damping term different from the common understanding. When the spin current exceeds the critical value, the conjunctive action of Gilbert damping and spin-transfer torque leads naturally the novel screw-pitch effect characterized by the temporal oscillation of domain wall velocity and width. Driven by space- and time-dependent spin-polarized current and magnetic field, we expatiate the formation of domain wall velocity in ferromagnetic nanowire. We discuss the properties of dynamic magnetic soliton in uniaxial anisotropic ferromagnetic nanowire driven by spin-transfer torque, and analyze the modulation instability and dark soliton on the spin wave background, which shows the characteristic breather behavior of the soliton as it propagates along the ferromagnetic nanowire. With stronger breather character, we get the novel magnetic rogue wave and clarify its formation mechanism. The generation of magnetic rogue wave mainly arises from the accumulation of energy and magnons toward to its central part. We also observe that the spin-polarized current can control the exchange rate of magnons between the envelope soliton and the background, and the critical current condition is obtained analytically. At last, we have theoretically investigated the current-excited and frequency-adjusted ferromagnetic resonance in magnetic trilayers. A particular case of the perpendicular analyzer reveals that the ferromagnetic resonance curves, including the resonant location and the resonant linewidth, can be adjusted by changing the pinned magnetization direction and the direct current. Under the control of the current and external magnetic field, several magnetic states, such as quasi-parallel and quasi-antiparallel stable states, out-of-plane precession, and bistable states can be realized. The precession frequency can be expressed as a function of the current and external magnetic field.
文摘The spin-transfer nano-oscillator （STNO） has recently acquired a huge amount of research interest, due to its promising easy tunability along with the miniature size. The output frequency control of an STNO through magnetic field and current has been examined almost to its full extent; however, there are issues that still need to be addressed. Here, we propose a novel way of voltage control of the output frequency of an STNO, and alongside reducing its power requirement.
基金support by the National Natural Science Foundation of China(Grant Nos.11074046,11274241,51171047 and 51222103)the Shuguang Program of Shanghai Education Commission(Grant No.09SG22)the New Century Educational Talents Plan of Chinese Education Ministry(Grant No.NCET-10-0603)
文摘Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access memory(MRAM) and spintorque oscillators.We review the fundamental mechanism and experimental progress of the STT effect.Then,different formula of STT torque has been classified,which can be added to the conventional Landau-Lifshitz-Gilbert equation.After that,we show some simulation results that mainly concern the STT-driven vortex dynamics,magnetization oscillations excited by a perpendicular polarizer,and the detail dynamics by in-plane and out-of-plane dual spin polarizers.
文摘电子自旋属性的自旋电子器件,由于其低能耗、高效率和强稳定性等特点,在磁性存储和计算技术的发展中发挥了重大作用。而如何以一种高能效、确定性和可扩展的方式对作为信息载体的磁性进行操控,这个重要问题在自旋电子学领域引起了利用电流操控磁化翻转的广泛研究。本文综述了利用自旋极化电流和纯自旋流操控磁化翻转的研究背景、重要工作和最新进展,详细介绍了自旋转移矩(spin transfer torque,STT)和自旋轨道矩(spinorbit torque,SOT)的产生和作用机制,重点阐述了利用SOT驱动磁畴壁运动和垂直磁化翻转,以及无外磁场磁化翻转的原理。最后探讨了SOT在人工合成反铁磁(synthetic antiferromagnet,SAF)结构中驱动的磁化翻转,为人工合成反铁磁体作为磁性随机访问存储器(magnetic random access memory,MRAM)的应用提供了重要基础,同时也为纯电流操控的自旋电子存储器件相关研究提供了有价值的参考。
