Detection of spin torque magnetization dynamics through low frequency noise

TL;DR

This paper compares high frequency oscillations and low frequency noise in magnetic tunnel junctions to understand spin-torque magnetization dynamics, proposing low frequency noise analysis as an effective investigative tool.

Contribution

It demonstrates that low frequency noise analysis can effectively reveal spin-torque magnetization dynamics, providing a simpler alternative to high frequency measurements.

Findings

Steady-state precession occurs at high negative bias currents above 10^7 A/cm^2.

Low frequency noise correlates with changes in oscillation modes under varying bias currents.

Low frequency noise analysis can serve as a straightforward method to study spin-torque dynamics.

Abstract

We present a comparative study of high frequency dynamics and low frequency noise in elliptical magnetic tunnel junctions with lateral dimensions under 100 nm presenting current-switching phenomena. The analysis of the high frequency oscillation modes with respect to the current reveals the onset of a steady-state precession regime for negative bias currents above $J=10^7 A/cm^2$, when the magnetic field is applied along the easy axis of magnetization. By the study of low frequency noise for the same samples, we demonstrate the direct link between changes in the oscillation modes with the applied current and the normalised low frequency (1/f) noise as a function of the bias current. These findings prove that low frequency noise studies could be a simple and powerful technique to investigate spin-torque based magnetization dynamics.