Magnetization precession due to a spin polarized current in a thin nanoelement: numerical simulation study

摘要

In this paper a detailed numerical study (in frames of the Slonczewskiformalism) of magnetization oscillations driven by a spin-polarized currentthrough a thin elliptical nanoelement is presented. We show that asophisticated micromagnetic model, where a polycrystalline structure of ananoelement is taken into account, can explain qualitatively all most importantfeatures of the magnetization oscillation spectra recently observedexperimentally (S.I. Kiselev et al., Nature, vol. 425, p. 380 (2003), namely:existence of several equidistant spectral bands, sharp onset and abruptdisappearance of magnetization oscillations with increasing current, absence ofthe out-of-plane regime predicted by a macrospin model and the relation betweenfrequencies of so called small-angle and quasichaotic oscillations. However, aquantitative agreement with experimental results (especially concerning thefrequency of quasichaotic oscillations) could not be achieved in the region ofreasonable parameter values, indicating that further model refinement isnecessary for a complete understanding of the spin-driven magnetizationprecession even in this relatively simple experimental situation.