Collective magnetism at multiferroic vortex domain walls

TL;DR

This study uncovers collective magnetic phenomena at vortex domain walls in multiferroic hexagonal ErMnO3, revealing field-controllable spin chirality and potential for nanoscale magnetoelectric devices.

Contribution

It demonstrates the existence of collective magnetism at vortex domain walls in multiferroic materials and introduces a model for field-controllable spin chirality.

Findings

Unprecedented alternating net moments at domain walls around vortices.

Correlation of magnetic moments across the vortex network.

Potential for magnetoelectric coupling at domain walls.

Abstract

Topological defects have been playgrounds for many emergent phenomena in complex matter such as superfluids, liquid crystals, and early universe. Recently, vortex-like topological defects with six interlocked structural antiphase and ferroelectric domains merging into a vortex core were revealed in multiferroic hexagonal manganites. Numerous vortices are found to form an intriguing self-organized network. Thus, it is imperative to find out the magnetic nature of these vortices. Using cryogenic magnetic force microscopy, we discovered unprecedented alternating net moments at domain walls around vortices that can correlate over the entire vortex network in hexagonal ErMnO3 The collective nature of domain wall magnetism originates from the uncompensated Er3+ moments and the correlated organization of the vortex network. Furthermore, our proposed model indicates a fascinating phenomenon of field-controllable spin chirality. Our results demonstrate a new route to achieving magnetoelectric coupling at domain walls in single-phase multiferroics, which may be harnessed for nanoscale multifunctional devices.