Time Domain Mapping of Spin Torque Oscillator Effective Energy

TL;DR

This paper introduces a time domain measurement method to map the effective energy surface of spin torque oscillators, enabling better predictions of spectral properties and measurement of spin torque components.

Contribution

It presents a novel time-resolved measurement technique to directly probe the effective energy landscape of STOs, enhancing understanding of their stochastic dynamics.

Findings

Effective energy surface can be directly mapped via time-resolved voltage measurements.

The method accurately predicts spectral line widths and shapes near threshold.

It enables measurement of the field-like spin torque component across various voltages.

Abstract

Stochastic dynamics of spin torque oscillators (STOs) can be described in terms of magnetization drift and diffusion over a current-dependent effective energy surface given by the Fokker-Planck equation. Here we present a method that directly probes this effective energy surface via time-resolved measurements of the microwave voltage generated by a STO. We show that the effective energy approach provides a simple recipe for predicting spectral line widths and line shapes near the generation threshold. Our time domain technique also accurately measures the field-like component of spin torque in a wide range of the voltage bias values.