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Advances in Condensed Matter Physics
Volume 2015, Article ID 457456, 6 pages
http://dx.doi.org/10.1155/2015/457456
Research Article

Analysis of Switchable Spin Torque Oscillator for Microwave Assisted Magnetic Recording

Data Storage Institute, Agency for Science, Technology and Research (A*STAR), Singapore 117608

Received 10 November 2014; Revised 25 February 2015; Accepted 1 March 2015

Academic Editor: Joseph S. Poon

Copyright © 2015 Mingsheng Zhang et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A switchable spin torque oscillator (STO) with a negative magnetic anisotropy oscillation layer for microwave assisted magnetic recording is analyzed theoretically and numerically. The equations for finding the STO frequency and oscillation angle are derived from Landau-Lifshitz-Gilbert (LLG) equation with the spin torque term in spherical coordinates. The theoretical analysis shows that the STO oscillating frequency remains the same and oscillation direction reverses after the switching of the magnetization of the spin polarization layer under applied alternative magnetic field. Numerical analysis based on the derived equations shows that the oscillation angle increases with the increase of the negative anisotropy energy density (absolute value) but decreases with the increase of spin current, the polarization of conduction electrons, the saturation magnetization, and the total applied magnetic field in the direction. The STO frequency increases with the increase of spin current, the polarization of conduction electrons, and the negative anisotropy energy density (absolute value) but decreases with the increase of the saturation magnetization and the total applied magnetic field in the direction.