Anti-chiral order and spin reorientation transitions of triangle-based antiferromagnets

TL;DR

This paper investigates how anti-chiral order in triangle-based antiferromagnets influences spin reorientation under in-plane magnetic fields, revealing complex transitions including first-order jumps and critical points, with implications for Mn$_3$Sn.

Contribution

It introduces the study of spin reorientation transitions in anti-chiral triangle-based antiferromagnets and characterizes the nature of these transitions, including critical points.

Findings

Spin orientation depends non-trivially on in-plane magnetic field.

Identification of first-order transitions with spin angle jumps.

Critical points in the Ising universality class.

Abstract

We show that triangle-based antiferromagnets with "anti-chiral" order display a non-trivial dependence of the spin orientation with an in-plane field. The spins evolve from rotating in the opposite sense to the field at very low fields to rotating in the same sense as the field above some critical field scale. In the latter regime the system displays first order transitions at which the spin angles jump, and these first order lines terminate in critical points in the Ising universality class. Application to Mn$_3$Sn is discussed.