Exploring non-collinear magnetic textures in multiferroics

Magnetic skyrmions are localized, non-collinear chiral magnetic textures which are envisioned to play a major role in spintronics [1] and neuromorphic computing [2] applications. Thanks to their topological properties that enhance their stability, ferromagnetic (FM) skyrmions in metals have been the subject of intense research in metals since the last 10 years.

Recently, their antiferromagnetic (AFM) counterparts have drawn attention due to their fast dynamics and their robustness against stray fields [3]. AFM skyrmion are characterized by a non-zero winding number associated to the AFM vector L. Although AFM skyrmions in a synthetic antiferromagnet have recently been reported, AFM skyrmions are still elusive in single-phase antiferromagnets.

Here, we first review the different stabilization and nucleation mechanisms of FM skyrmions in metals [4,5]. Both FM and AFM skyrmions are stabilized by similar interactions: the magnetic exchange interaction, the Dzyaloshinskii-Moriya (DM) interaction and the magnetic anisotropy. Via density functional theory, we explore the magnetic ground state of the AFM multiferroics BiFeO₃ as a function of structure and strain [6]. For each case, the magnetic exchange, the DM interaction and the magnetocrystalline anisotropy energy are extracted.