We evaluate the spin-wave spectra for the high-field phases of the frustrated triangular lattice antiferromagnet with a focus on the observed high-magnetic-field phases of CuFeO${}_2$. After determining the appropriate magnetic ground state using a combination of Monte Carlo simulations and variational methods for a two-dimensional triangular lattice, we evaluate the spin excitation frequencies and intensities using a rotational Holstein-Primakoff expansion for both the collinear and noncollinear states. These predictions should help experimentalists to identify the magnetic ground states of CuFeO${}_2$ and other triangular-lattice antiferromagnets using inelastic neutron scattering.

• Received 11 January 2012

DOI:https://doi.org/10.1103/PhysRevB.86.024412