Alternating current driven instability in magnetic junctions

TL;DR

This paper investigates how high-frequency alternating current affects the stability of magnetic junctions, revealing conditions for parametric resonance and instability in different configurations, with implications for magnetic device control.

Contribution

It introduces an analysis of AC-driven instability in magnetic junctions, highlighting resonance effects and stability thresholds in a macrospin model.

Findings

Parametric resonance occurs near the eigenfrequency of the free layer.

Both parallel and antiparallel configurations can become unstable under resonance.

Threshold current density for instability is comparable to DC switching current.

Abstract

An effect is considered of alternating (high-frequency) current on the spin-valve type magnetic junction configuration. The stability with respect to small fluctuations is investigated in the macrospin approximation. When the current frequency is close to the eigenfrequency (precession frequency) of the free layer, parametric resonance occurs. Both collinear configurations, antiparallel and parallel ones, can become unstable under resonance conditions. The antiparallel configuration can become unstable under non-resonant conditions, also. The threshold current density amplitude is of the order of the dc current density switching the magnetic junction.