Direct experimental measurement of phase-amplitude coupling in spin torque oscillators

TL;DR

This paper presents the first direct experimental measurement of phase-amplitude coupling in spin torque oscillators, revealing weak coupling strength and insights into power restoration dynamics.

Contribution

It introduces a novel experimental approach using Hilbert transform to measure phase-amplitude coupling in spin-torque oscillators.

Findings

Weak phase-amplitude coupling strength observed

Power restoration rate deduced from measurements

Coupling strength shows weak voltage dependence

Abstract

We study spin-torque induced oscillations of MgO magnetic tunnel junctions in the time domain. By using the Hilbert transform on the time traces, we obtain for the first time a direct experimental measure of the coupling between the power and the phase fluctuations. We deduce the power restoration rate and we obtain low values for the coupling strength, which is consistent with the weak frequency dependence on the applied voltage.