Spin-Wave Instabilities and Non-Collinear Magnetic Phases of a Geometrically-Frustrated Triangular-Lattice Antiferromagnet

TL;DR

This study explores how spin-wave instabilities lead to non-collinear magnetic phases in a frustrated triangular-lattice antiferromagnet, linking theoretical predictions to observed multiferroic behavior in Al-doped CuFeO2.

Contribution

It reveals the connection between spin-wave instabilities and the emergence of non-collinear phases in a geometrically-frustrated system using phenomenological and Monte Carlo methods.

Findings

Instability wave-vector determines non-collinear phase structure.

Results relate to multiferroic phase in Al-doped CuFeO2.

Strong correlation between spin-wave instabilities and magnetic phase transitions.

Abstract

This paper examines the relation between the spin-wave instabilities of collinear magnetic phases and the resulting non-collinear phases for a geometrically-frustrated triangular-lattice antiferromagnet in the high spin limit. Using a combination of phenomenological and Monte-Carlo techniques, we demonstrate that the instability wave-vector with the strongest intensity in the collinear phase determines the wave-vector of a cycloid or the dominant elastic peak of a more complex non-collinear phase. Our results are related to the observed multi-ferroic phase of Al-doped CuFeO$_2$.