Degenerate skyrmionic states in synthetic antiferromagnets

TL;DR

This paper explores the stabilization and coexistence of novel topological magnetic textures, including skyrmions and antiskyrmions, in a synthetic antiferromagnetic system with tailored DMI interactions, expanding potential for magnetic memory applications.

Contribution

It introduces a new approach using a SAF system with different DMI properties in each layer to stabilize and coexist novel topological textures, including degenerate skyrmionic states.

Findings

Coexistence of skyrmions and antiskyrmions in SAF systems.

Stabilization of six novel elliptical topological textures.

Potential for advanced magnetic memory devices.

Abstract

Topological magnetic textures, characterized by integer topological charge $S$, are potential candidates in future magnetic logic and memory devices, due to their smaller size and expected low threshold current density for their motion. An essential requirement to stabilize them is the Dzyaloshinskii-Moriya interaction (DMI) which promotes a particular chirality, leading to a unique value of $S$ in a given material. However, recently coexistence of skyrmions and antiskyrmions, with opposite topological charge, in frustrated ferromagnets has been predicted using $J_1$--$J_2$--$J_3$ classical Heisenberg model, which opens new perspectives, to use the topological charge as an additional degree of freedom. In this work, we propose another approach of using a synthetic antiferromagnetic (SAF) system, where one of the ferromagnetic (FM) layer has isotropic and the other FM layer has anisotropic DMI to promote the existence of skyrmions and antiskyrmions, respectively. A frustrated interaction arises due to the coupling between the magnetic textures in the FM layers, which enables the stabilization and coexistence of 6 novel elliptical topological textures.