Weak antiferromagnetic ordering and pure magnetic reflections induced by Dzyaloshinskii-Moriya interaction in MnSi-type crystals

TL;DR

This paper analyzes how Dzyaloshinskii-Moriya interactions in MnSi-type crystals induce weak antiferromagnetic order and forbidden magnetic reflections, providing theoretical predictions for experimental detection.

Contribution

It demonstrates that DM interactions cause periodic tilting of magnetic moments, leading to weak antiferromagnetic patterns and forbidden reflections, with calculated structure factors for various field orientations.

Findings

Weak antiferromagnetic pattern induced by DM interaction

Forbidden magnetic reflections 00l with l=2n+1 predicted

Tilt angles of Mn sublattices determined theoretically

Abstract

Symmetry analysis of the Dzyaloshinskii-Moriya (DM) interaction in MnSi-type cubic crystals demonstrates that the magnetic moments are tilted periodically, producing a weak antiferromagnetic pattern, when the helix is unwound by magnetic field. The tilt angles of four Mn sublattices are determined by a component of the DM vector perpendicular to that one responsible for helical spiraling; both components have been evaluated using a simple model. It is shown that the tilting should induce pure magnetic reflections 00l, l=2n+1 in neutron or x-ray magnetic scattering, and the structure factors of these "forbidden" reflections are calculated for arbitrary field orientations.