Switching induced by spin Hall effect in an in-plane magnetized ferromagnet with the easy axis parallel to the current

TL;DR

This paper develops an analytical theory for current-induced magnetization switching via the spin Hall effect in in-plane magnetized ferromagnets, clarifying the threshold current conditions for deterministic switching.

Contribution

It introduces a new analytical model that explains the switching mechanism and threshold currents in in-plane ferromagnets with the easy axis parallel to the current.

Findings

Threshold current range for deterministic switching identified

Large currents outside the range cause magnetization precession

Analytical formulas for switching thresholds derived

Abstract

Magnetization switching in a fine-structured ferromagnet of nanoscale by the spin-transfer torque excited via the spin Hall effect has attracted much attention because it enables us to manipulate the magnetization without directly applying current to the ferromagnet. However, the switching mechanism is still unclear in regard to the ferromagnet having an in-plane easy axis parallel to the current. Here, we develop an analytical theory of the magnetization switching in this type of ferromagnet, and reveal the threshold current formulas for a deterministic switching. It is clarified that the current should be in between a certain range determined by two threshold currents because the spin-transfer torque due to a large current outside the range brings the magnetization in an energetically unstable state, and causes magnetization precession around the hard axis.