Spin dynamics in the geometrically frustrated multiferroic CuCrO2

TL;DR

This study investigates the spin dynamics of the multiferroic CuCrO2 using inelastic neutron scattering, revealing the magnetic interactions that stabilize its ferroelectric order and providing insights for designing new multiferroic materials.

Contribution

The paper determines the spin Hamiltonian parameters for CuCrO2 and elucidates the magnetic interactions responsible for its multiferroic properties, highlighting the role of interlayer coupling.

Findings

Identification of antiferromagnetic and ferromagnetic interactions in CuCrO2

Weakly dispersive excitation indicates two-dimensional magnetic character

Balance of interlayer interactions stabilizes ferroelectric magnetic order

Abstract

The spin dynamics of the geometrically frustrated triangular antiferromagnet multiferroic CuCrO2 have been mapped out using inelastic neutron scattering. The relevant spin Hamiltonian parameters modelling the incommensurate modulated helicoid have been determined, and correspond to antiferromagnetic nearest and next-nearest neighbour interactions in the ab plane, with a strong planar anisotropy. The weakly dispersive excitation along c reflects the essentially two-dimensional character of the magnetic interactions and according to classical energy calculations it is weakly ferromagnetic. Our results clearly point out the relevance of the balance between a ferromagnetic coupling between adjacent planes and a weakly antiferromagnetic next-nearest neighbour interaction in stabilising the three-dimensional ferroelectric magnetic order in CuCrO2. This novel insight on the interplay between magnetic interactions in CuCrO2 should provide a useful basis in the design of new delafossite-based multiferroic materials.