Stability and Character of Zero Field Skyrmionic States in Hybrid Magnetic Multilayer Nanodots

TL;DR

This study demonstrates the stabilization of small, zero-field skyrmions and target skyrmions in hybrid multilayer nanodots, advancing the development of skyrmionic devices for memory and computing applications.

Contribution

The paper introduces a hybrid multilayer platform enabling stable zero-field skyrmions and target skyrmions in nanodots, combining metallic and oxide layers for improved stability and control.

Findings

Zero-field skyrmions as small as 50 nm stabilized in hybrid nanodots.

Skyrmion sizes modulated by CoB thickness and dot size.

Observation of higher order 'target' skyrmions in low anisotropy nanodots.

Abstract

Ambient magnetic skyrmions stabilized in multilayer nanostructures are of immense interest due to their relevance to magnetic tunnel junction (MTJ) devices for memory and unconventional computing applications. However, existing skyrmionic nanostructures built using conventional metallic or oxide multilayer nanodots are unable to concurrently fulfill the requirements of nanoscale skyrmion stability and feasibility of all-electrical readout and manipulation. Here, we develop a few-repeat hybrid multilayer platform consisting of metallic [Pt/CoB/Ir]3 and oxide [Pt/CoB/MgO] components that are coupled to evolve together as a single, composite stack. Zero-field (ZF) skyrmions with sizes as small as 50 nm are stabilized in the hybrid multilayer nanodots, which are smoothly modulated by up to 2.5x by varying CoB thickness and dot sizes. Meanwhile, skyrmion multiplets are also stabilized by small bias fields. Crucially, we observe higher order 'target' skyrmions with varying magnetization rotations in moderately-sized, low anisotropy nanodots. These results provide a viable route to realize long-sought skyrmionic MTJ devices and new possibilities for multi-state skyrmionic device concepts.