Spin dynamics in the geometrically frustrated multiferroic CuCrO2

The spin dynamics of the geometrically frustrated triangular antiferromagnet multiferroic CuCrO2 have been mapped out using inelastic neutron scattering. The relevant spin Hamiltonian parameters modeling the incommensurate modulated helicoid have been determined, and correspond to antiferromagnetic nearest- and next-nearest-neighbor 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. Classical energy calculations clearly point out the relevance of the balance between the adjacent planes coupling, the in-plane nearest-neighbor interactions anisotropy, and a weakly antiferromagnetic next-nearest-neighbor interaction, in stabilizing the three-dimensional magnetic order in CuCrO2.