Stable oscillation in spin torque oscillator excited by a small in-plane magnetic field

TL;DR

This paper analytically investigates the conditions for stable self-oscillation in a spin torque oscillator with specific magnetic layer configurations, revealing that small in-plane magnetic fields can induce large amplitude oscillations.

Contribution

It derives an analytical relation between current and oscillation frequency and confirms the findings with numerical simulations, advancing understanding of spin torque oscillator dynamics.

Findings

Large amplitude oscillation can be excited with a small in-plane magnetic field.

Analytical and numerical results show good agreement in low current regions.

The study provides conditions for stable self-oscillation in specific magnetic layer configurations.

Abstract

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.