Acoustic-Wave-Induced Ferromagnetic-Resonance-Assisted Spin-Torque Switching of Perpendicular Magnetic Tunnel Junctions with Anisotropy Variation
Acoustic-Wave-Induced Ferromagnetic-Resonance-Assisted Spin-Torque Switching of Perpendicular Magnetic Tunnel Junctions with Anisotropy Variation
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DOI：
10.1103/physrevapplied.14.014088
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
W. A. Misba;M. Rajib;Dhritiman Bhattacharya;J. Atulasimha
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文献类型：
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作者：
W. A. Misba;M. Rajib;Dhritiman Bhattacharya;J. Atulasimha
我们已经研究了表面声波（SAW）诱导的铁磁共振（FMR）辅助自旋转移力矩（STT）开关的垂直MTJ（p-MTJ）的非均匀性使用微磁模拟，包括热噪声的影响。在适当的频率激励下，声表面波能在磁致伸缩材料中诱发铁磁共振，使磁化强度沿垂直于磁致伸缩材料方向的大偏转圆锥进动。随着通过横向各向异性变化以及室温热噪声的不均匀性的并入，在不同增益下的磁化旋进可以是显著不相干的。有趣的是，不同晶粒中的进动被发现是同相的，即使进动幅度（从垂直方向的偏转角）在不同各向异性的晶粒之间变化。然而，高平均偏转角可以通过显著降低STT电流来补充STT切换;即使施加的应力引起的各向异性变化远低于总各向异性势垒。这项工作表明，SAW辅助开关可以提高能量效率，同时可扩展到非常小的尺寸，这对STT-RAM具有重要的技术意义，并阐明了这种范例在具有热噪声和材料不均匀性的现实场景中的潜在鲁棒性的物理机制
We have investigated Surface Acoustic Wave (SAW) induced ferromagnetic resonance (FMR) assisted Spin Transfer Torque (STT) switching of perpendicular MTJ (p-MTJ) with inhomogeneities using micromagnetic simulations that include the effect of thermal noise. With suitable frequency excitation, the SAW can induce ferromagnetic resonance in magnetostrictive materials, and the magnetization can precesses in a cone with high deflection from the perpendicular direction. With incorporation of inhomogeneity via lateral anisotropy variation as well as room temperature thermal noise, the magnetization precession in different gains can be significantly incoherent. Interestingly, the precession in different grains are found to be in phase, even though the precession amplitude (angle of deflection from the perpendicular direction) vary across grains of different anisotropy. Nevertheless, the high mean deflection angle can complement the STT switching by reducing the STT current significantly; even though the applied stress induced change in anisotropy is much lower than the total anisotropy barrier. This work indicates that SAW assisted switching can improve energy efficiency while being scalable to very small dimensions, which is technologically important for STT-RAM and elucidates the physical mechanism for the potential robustness of this paradigm in realistic scenarios with thermal noise and material inhomogeneity