Using high-resolution inelastic neutron scattering, we examine the spin dynamics of Mn1-xCoxWO4 in the collinear AF1, the ac-b spiral AF2, and the ac cycloidal AF5 phases. The spin wave excitations are well described by a Heisenberg model with competing long-range exchange interactions (Ji up to 12th nearest neighbors) and the single-ion anisotropy K induced by the spin-orbit interaction. While the exchange constants are relatively unchanged, the dominant effect of doping is to change the single-ion anisotropy from easy axis (K>0) in the collinear AF1 phase to easy plane (K<0) in the two multiferroic phases.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics