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

TL;DR

This study uses detailed numerical simulations to analyze magnetization oscillations driven by spin-polarized currents in nanoelements, revealing qualitative agreement with experiments but highlighting the need for further model refinement for quantitative accuracy.

Contribution

It introduces a sophisticated micromagnetic model accounting for polycrystalline structure to explain experimental features of spin-driven magnetization precession.

Findings

Qualitative agreement with experimental spectra features

Identification of model limitations in frequency predictions

Observation of abrupt oscillation onset and disappearance

Abstract

In this paper a detailed numerical study (in frames of the Slonczewski formalism) of magnetization oscillations driven by a spin-polarized current through a thin elliptical nanoelement is presented. We show that a sophisticated micromagnetic model, where a polycrystalline structure of a nanoelement is taken into account, can explain qualitatively all most important features of the magnetization oscillation spectra recently observed experimentally (S.I. Kiselev et al., Nature, vol. 425, p. 380 (2003), namely: existence of several equidistant spectral bands, sharp onset and abrupt disappearance of magnetization oscillations with increasing current, absence of the out-of-plane regime predicted by a macrospin model and the relation between frequencies of so called small-angle and quasichaotic oscillations. However, a quantitative agreement with experimental results (especially concerning the frequency of quasichaotic oscillations) could not be achieved in the region of reasonable parameter values, indicating that further model refinement is necessary for a complete understanding of the spin-driven magnetization precession even in this relatively simple experimental situation.