Theoretical Conditions for Field-free Magnetization Switching Induced by Spin-orbit Torque and Dzyaloshinskii-Moriya Interaction

TL;DR

This paper establishes theoretical conditions for field-free magnetization switching driven by spin-orbit torque and Dzyaloshinskii-Moriya interaction, emphasizing the role of domain wall properties and magnetic parameters.

Contribution

It introduces a criterion based on domain wall width and nanodot diameter, and analyzes the effects of magnetic parameters on DMI-induced switching mechanisms.

Findings

Domain wall width to nanodot diameter ratio as a switching criterion

Magnetic parameters influence switching behavior significantly

Shrinkage of domain wall surface energy affects metastable states

Abstract

Recently, it was demonstrated that field-free switching could be achieved by combining spin-orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI). However, this mechanism only occurs under certain conditions which have not been well discussed. In this letter, it is found that the ratio of domain wall width to diameter of nanodots could be utilized as a criteria for judging this mechanism. Influences of different magnetic parameters are studied, including exchange constant, DMI magnitude and field-like toque, etc. Besides, we reveal the importance of the shrinkage of magnetic domain wall surface energy for metastable states. Our work provides guidelines to the experiments on the DMI-induced field-free magnetization switching, and also offers a new way for the design of SOT-based memory or logic circuits.