Non-Collinear Magnetic Phases of a Triangular-Lattice Antiferromagnet and Doped CuFeO$_2$

TL;DR

This paper explores the complex non-collinear magnetic phases in a triangular-lattice antiferromagnet, revealing how doping and lattice distortions influence magnetic ordering and phase transitions.

Contribution

It provides a theoretical analysis of non-collinear ground states in a triangular-lattice antiferromagnet considering third-nearest-neighbor interactions and lattice distortions.

Findings

Transition from collinear to non-collinear phase at critical anisotropy D

Explanation of elastic peaks via scalene lattice distortion

Identification of odd-order harmonics in magnetic ordering

Abstract

We obtain the non-collinear ground states of a triangular-lattice antiferromagnet with exchange interactions up to third nearest neighbors as a function of the single-ion anisotropy $D$. At a critical value of $D$, the collinear $\uudd $ phase transforms into a complex non-collinear phase with odd-order harmonics of the fundamental ordering wavevector $\vQ $. The observed elastic peaks at $2\pi \vx -\vQ $ in both Al- and Ga- doped CuFeO$_2$ are explained by a "scalene" distortion of the triangular lattice produced by the repulsion of neighboring oxygen atoms.