1304.1284 (Ran Cheng et al.)
Ran Cheng, Qian Niu
When a spin-polarized current flows through a ferromagnetic (FM) metal, angular momentum is transferred to the magnetization via spin transfer torques. In antiferromagnetic (AFM) materials, however, corresponding problems are unsolved puzzles despite their potential applications are anticipated. We derive microscopically the dynamics of an AFM system driven by spin-polarized current, and find that a spin current is able to drive local staggered order directly without inducing FM moments on top of the AFM background. Rather than producing a torque, the spin current exerts a driving force determining second order dynamics of the local staggered order. Two examples are studied: (i) A domain wall is accelerated to a terminal velocity by purely adiabatic effect and no Walker's break-down exists. (ii) Injection of spin imbalance splits the AFM resonance frequencies and a sufficiently large spin current triggers spin-wave instability.
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http://arxiv.org/abs/1304.1284
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