Gradient-induced Dzyaloshinskii-Moriya interaction

TL;DR

This paper investigates a new type of Dzyaloshinskii-Moriya interaction (g-DMI) in composition-graded magnetic films, showing how it can be controlled and used to create chiral magnetic structures and enable spintronic device functionalities.

Contribution

It introduces and characterizes g-DMI in composition-gradient films, revealing its controllability, additive nature, and potential for engineering magnetic textures and spin-orbit torque applications.

Findings

g-DMI strength and chirality are tunable via composition gradient.

g-DMI induces chiral magnetic structures like skyrmions and spin spirals.

g-DMI enables field-free spin-orbit torque switching.

Abstract

The Dzyaloshinskii-Moriya interaction (DMI) that arises in the magnetic systems with broken inversion symmetry plays an essential role in topological spintronics. Here, by means of atomistic spin calculations, we study an intriguing type of DMI (g-DMI) that emerges in the films with composition gradient. We show that both the strength and chirality of g-DMI can be controlled by the composition gradient even in the disordered system. The layer-resolved analysis of g-DMI unveils its additive nature inside the bulk layers and clarifies the linear thickness dependence of g-DMI observed in experiments. Furthermore, we demonstrate the g-DMI induced chiral magnetic structures, such as spin spirals and skyrmions, and the g-DMI driven field-free spin-orbit torque (SOT) switching, both of which are crucial towards practical device application. These results elucidate the underlying mechanisms of g-DMI and open up a new way to engineer the topological magnetic textures.