Field-induced double spin spiral in a frustrated chiral magnet

TL;DR

This study demonstrates a field-induced long-wavelength spin spiral in a chiral magnet, revealing a new magnetic texture with potential topological stability and implications for multiferroic properties.

Contribution

It reports the discovery of a field-induced spin spiral in a chiral magnet, highlighting its unique electric polarization and potential for topologically stable antiferromagnetic skyrmions.

Findings

Observation of a long-wavelength spin spiral modulated by magnetic field

The spin spiral's periodicity is several hundred nanometers

The phase transition aligns with Lifshitz invariants for chiral symmetry

Abstract

We report the direct observation of a magnetic-feld induced long-wavelength spin spiral modulation in the chiral compound Ba3TaFe3Si2O14. This new spin texture emerges out of a chiral helical ground state, and is hallmarked by the onset of a unique contribution to the bulk electric polarization, the sign of which depends on the crystal chirality. The periodicity of the feld induced modulation, several hundreds of nm depending on the field value, is comparable to the length scales of mesoscopic topological defects such as skyrmions, merons and solitons. The phase transition and observed threshold behavior are consistent with a phenomenology based on the allowed Lifshitz invariants for the chiral symmetry of langasite, which intriguingly contain all the ingredients for the possible realization of topologically stable antiferromagnetic skyrmions.