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Publication Citation: Self-consistent calculation of spin transport and magnetization dynamics

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Author(s): Kyung Jin Lee; Mark D. Stiles; Hyun-Woo Lee; Jung-Hwan Moon; Kyoung-Whan Kim; Seo--Won Lee;
Title: Self-consistent calculation of spin transport and magnetization dynamics
Published: October 10, 2013
Abstract: A spin-polarized current transfers its spin-angular momentum to a local magnetization, exciting various types of current-induced magnetization dynamics. So far, most studies in this field have focused on the direct effect of spin transport on magnetization dynamics, but ignored the feedback from the magnetization dynamics to the spin transport and back to the magnetization dynamics. Although the feedback is usually weak, there are situations when it can play an important role in the dynamics. In such situations, simultaneous, self-consistent calculations of the magnetization dynamics and the spin transport can accurately describe the feedback. This review describes in detail the feedback mechanisms, and presents recent progress in self-consistent calculations of the coupled dynamics. We pay special attention to three representative examples, where the feedback generates non-local spin transfer torques. Possibly the most dramatic feedback example is the dynamic instability in magnetic nanopillars with a single magnetic layer. This instability does not occur without non-local feedback. We demonstrate that full self-consistent calculations generate simulation results in much better agreement with experiments than previous calculations that addressed the feedback effect approximately. The next example is for more typical spin valve nanopillars. Although the effect of feedback is less dramatic in that the current can make stationary states unstable and induce magnetization oscillation even without the feedback, it still has important consequences. For instance, we show that the feedback can reduce the linewidth of oscillations, in agreement with experimental observations. A key aspect of this reduction is the suppression of short wave length spin waves by the non-local feedback. Finally, we consider nonadiabatic electron transport in narrow domain walls. The non-local feedback in these systems leads to a significant [Remaining chopped by character limit]
Citation: Physics Reports-Review Section of Physics Letters
Volume: 531
Issue: 2
Pages: pp. 89 - 113
Keywords: magnetic multilayers; spin transfer torque; magnetization dynamics, spin transport; magnetic nanopillars; feedback; simulations; Landau-Lifshitz-Gilbert equation; spin waves; dynamical instability; non-adiabatic spin transfer torque
Research Areas: Nanomagnetics
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