Thermally-Activated Magnetic Reversal Induced by a Spin-Polarized Current

TL;DR

This paper investigates how spin-polarized currents induce thermally-activated magnetic reversal in nanomagnets, revealing unique behaviors distinct from magnetic field effects and presenting an effective phase diagram.

Contribution

It introduces a detailed analysis of spin-transfer-driven reversal, highlighting its differences from field-induced reversal and proposing an effective current-field phase diagram.

Findings

Reversal exhibits thermally-activated escape over an effective barrier.

Spin-transfer effects produce qualitatively different behaviors than magnetic fields.

Magnet can be driven superparamagnetic when current and field oppose each other.

Abstract

We have measured the statistical properties of magnetic reversal in nanomagnets driven by a spin-polarized current. Like reversal induced by a magnetic field, spin-transfer-driven reversal near room temperature exhibits the properties of thermally-activated escape over an effective barrier. However, the spin-transfer effect produces qualitatively different behaviors than an applied magnetic field. We discuss an effective current vs. field phase diagram. If the current and field are tuned so that their effects oppose one another, the magnet can be driven superparamagnetic.