Dynamics of spin torque switching in all-perpendicular spin valve nanopillars
Dynamics of spin torque switching in all-perpendicular spin valve nanopillars
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DOI：
10.1016/j.jmmm.2014.01.061
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发表时间：
2014-05-01
影响因子：
2.7
通讯作者：
Kent, A. D.
中科院分区：
文献类型：
--
作者：
Liu, H.;Bedau, D.;Kent, A. D.
本文以全垂直磁化自旋阀为模型系统，系统地研究了室温下自旋力矩诱导的磁开关统计特性。区分三个物理制度：短时间弹道限制低于几纳秒，其中自旋扭矩占主导地位的反转动力学从初始条件的热分布;一个长的时间限制，其中的磁化反转概率是由自旋扭矩放大的热激活;和交叉制度，其中的自旋扭矩和热搅拌都有助于。对于所涉及的物理过程的基本定量的理解，分析宏观自旋模型，其中包含自旋扭矩动力学和有限温度效应。后者被严格对待使用福克-普朗克形式主义，并解决了具体的参数集的数值实验，以确定在短时间内的切换概率行为和交叉制度。该分析表明，在磁化反转过程中的热波动极大地影响开关的概率在所有的时间尺度上研究，即使在很短的时间限制。(C)2014 Elsevier B. V.保留所有权利，
We present a systematic experimental study of the spin-torque-induced magnetic switching statistics at room temperature, using all-perpendicularly magnetized spin-valves as a model system. Three physical regimes are distinguished: a short-time ballistic limit below a few nanoseconds, where spin-torque dominates the reversal dynamics from a thermal distribution of initial conditions; a long time limit, where the magnetization reversal probability is determined by spin-torque-amplified thermal activation; and a cross-over regime, where the spin-torque and thermal agitation both contribute. For a basic quantitative understanding of the physical processes involved, an analytical macrospin model is presented which contains both spin-torque dynamics and finite temperature effects. The latter was treated rigorously using a Fokker-Plank formalism, and solved numerically for specific sets of parameters relevant to the experiments to determine the switching probability behavior in the short time and cross over regimes. This analysis shows that thermal fluctuations during magnetization reversal greatly affect the switching probability over all the time scales studied, even in the short time limit. (C) 2014 Elsevier B.V. All rights reserved,