Theoretical Study of Spin-Torque Oscillator with Perpendicularly Magnetized Free Layer

TL;DR

This paper provides an analytical study of the magnetization dynamics in a spin torque oscillator with a perpendicularly magnetized free layer, revealing how current influences oscillation frequency and the impact of field-like torque.

Contribution

It derives an analytical formula linking current and oscillation frequency in STOs and analyzes the effect of field-like torque on energy balance and frequency.

Findings

Derived an analytical formula for current-frequency relation.

Identified the role of field-like torque in frequency modulation.

Analyzed energy balance in magnetization dynamics.

Abstract

The magnetization dynamics of spin torque oscillator (STO) consisting of a perpendicularly magnetized free layer and an in-plane magnetized pinned layer was studied by solving the Landau-Lifshitz-Gilbert equation. We derived the analytical formula of the relation between the current and the oscillation frequency of the STO by analyzing the energy balance between the work done by the spin torque and the energy dissipation due to the damping. We also found that the field-like torque breaks the energy balance, and change the oscillation frequency.