Theoretical conditions to excite self-oscillation in a spin torque oscillator consisting of a perpendicularly magnetized free layer and an in-plane magnetized pinned layer are investigated by analytically solving the Landau-Lifshitz-Gilbert equation. The analytical relation between the current and oscillation frequency is derived. It is found that a large amplitude oscillation can be excited by applying a small field pointing to the direction anti-parallel to the magnetization of the pinned layer. The validity of the analytical results is confirmed by comparing with numerical simulation, showing good agreement especially in a low current region.
@article{arxiv.1508.00601,
title = {Stable oscillation in spin torque oscillator excited by a small in-plane magnetic field},
author = {Tomohiro Taniguchi and Takahiro Ito and Yasuhiro Utsumi and Sumito Tsunegi and Hitoshi Kubota},
journal= {arXiv preprint arXiv:1508.00601},
year = {2015}
}