Parameter dependence of resonant spin torque magnetization reversal

TL;DR

This paper investigates how the parameters of combined DC and resonant AC current pulses affect the speed, energy efficiency, and reliability of magnetization reversal in magnetic tunnel junctions, revealing optimal conditions and potential pitfalls.

Contribution

It introduces a detailed numerical analysis of resonant spin torque reversal considering various pulse parameters, highlighting conditions for robust and efficient switching.

Findings

Resonant AC and DC currents can achieve faster, more energy-efficient reversal.

Reversal reliability strongly depends on AC frequency and phase.

Unreliable reversal regions should be avoided in applications.

Abstract

We numerically study ultra fast resonant spin torque (ST) magnetization reversal in magnetic tunnelling junctions (MTJ) driven by current pulses having a direct current (DC) and a resonant alternating current (AC) component. The precessional ST dynamics of the single domain MTJ free layer cell are modelled in the macro spin approximation. The energy efficiency, reversal time, and reversal reliability are investigated under variation of pulse parameters like direct and AC current amplitude, AC frequency and AC phase. We find a range of AC and direct current amplitudes where robust resonant ST reversal is obtained with faster switching time and reduced energy consumption per pulse compared to purely direct current ST reversal. However for a certain range of AC and direct current amplitudes a strong dependence of the reversal properties on AC frequency and phase is found. Such regions of unreliable reversal must be avoided for ST memory applications.