Tuning interfacial Dzyaloshinskii-Moriya interactions in thin amorphous ferrimagnetic alloys

TL;DR

This study systematically investigates how to tune interfacial Dzyaloshinskii-Moriya interactions in ferrimagnetic CoGd films, enabling stabilization of sub-100 nm skyrmions at room temperature for potential spintronic applications.

Contribution

It demonstrates control over DMI via layer composition, symmetry, and thickness in ferrimagnetic alloys, a less explored area compared to ferromagnets.

Findings

DMI can be tuned by CoGd cap layer composition.

DMI depends on stack symmetry and layer thickness.

Sub-100 nm skyrmions are stabilized at room temperature.

Abstract

Skyrmions can be stabilized in magnetic systems with broken inversion symmetry and chiral interactions, such as Dzyaloshinskii-Moriya interactions (DMI). Further, compensation of magnetic moments in ferrimagnetic materials can significantly reduce magnetic dipolar interactions, which tend to favor large skyrmions. Tuning DMI is essential to control skyrmion properties, with symmetry breaking at interfaces offering the greatest flexibility. However, in contrast to the ferromagnet case, few studies have investigated interfacial DMI in ferrimagnets. Here we present a systematic study of DMI in ferrimagnetic CoGd films by Brillouin light scattering. We demonstrate the ability to control DMI by the CoGd cap layer composition, the stack symmetry and the ferrimagnetic layer thickness. The DMI thickness dependence confirms its interfacial nature. In addition, magnetic force microscopy reveals the ability to tune DMI in a range that stabilizes sub-100 nm skyrmions at room temperature in zero field. Our work opens new paths for controlling interfacial DMI in ferrimagnets to nucleate and manipulate skyrmions.