Deterministically switching the Bloch chirality of domain walls and skyrmions: the Dzyaloshinskii astroid

TL;DR

This paper introduces a deterministic method to control the Bloch chirality of magnetic domain walls and skyrmions using the interplay of Dzyaloshinskii-Moriya interaction and magnetic fields, supported by analytical and micromagnetic analyses.

Contribution

It presents a novel switching diagram for Bloch chirality, akin to the Stoner–Wohlfarth astroid, revealing regimes of achiral, chiral, and precessional states, and extends the understanding of skyrmion behavior.

Findings

Chirality switching depends on the magnetic field direction.

Existence of achiral, chiral, and precessional regimes in the switching diagram.

Skyrmions exhibit similar chirality switching behavior as domain walls.

Abstract

We present a mechanism for deterministic control of the Bloch chirality in magnetic domain walls and skyrmions, originating from the interplay between an interfacial Dzyaloshinskii$-$Moriya interaction (DMI) and a perpendicular magnetic field. Although conventional interfacial DMI favors chiral N\'eel skyrmions, it does not break the energetic symmetry of the two Bloch chiralities in mixed Bloch$-$N\'eel skyrmions. However, the energy barrier to switching between Bloch chiralities does depend on the sense of rotation, which is dictated by the direction of the driving field. Our analytical and micromagnetic analyses of steady-state Dzyaloshinskii domain wall dynamics culminates in a switching diagram akin to the Stoner$-$Wohlfarth astroid, revealing the existence of achiral, chiral, and precessional Bloch regimes; we further show that in view of established energetic models, skyrmions should exhibit the same fundamental behavior. Finally, we discuss a recent theory of vertical Bloch line$-$mediated deterministic Bloch chirality in the precessional regime and extend these arguments to lower driving fields. This work establishes that the Bloch chirality of magnetic solitons can be switched on demand with applied fields, as indicated by the Dzyaloshinskii astroid.