Single domain magnetic helicity and triangular chirality in structurally enantiopure Ba3NbFe3Si2O14

TL;DR

This study uncovers a unique doubly chiral magnetic order in the enantiopure langasite compound Ba3NbFe3Si2O14, characterized by a helical modulation and a single triangular chirality, advancing understanding of chiral magnetic structures.

Contribution

It reports the discovery of a novel doubly chiral magnetic order in a structurally chiral compound, with experimental and theoretical analysis of its magnetic configuration.

Findings

Single triangular chirality and helicity stabilized in the crystal

Helical modulation of magnetic moments across layers

Relevance of superexchange paths in magnetic order

Abstract

A novel doubly chiral magnetic order is found out in the structurally chiral langasite compound Ba$_3$NbFe$_3$Si$_2$O$_{14}$. The magnetic moments are distributed over planar frustrated triangular lattices of triangle units. On each of these they form the same triangular configuration. This ferro-chiral arrangement is helically modulated from plane to plane. Unpolarized neutron scattering on a single crystal associated with spherical neutron polarimetry proved that a single triangular chirality together with a single helicity is stabilized in an enantiopure crystal. A mean field analysis allows discerning the relevance on this selection of a twist in the plane to plane supersuperexchange paths.