Ferrimagnetic Resonance in NiMnO3

Ferrimagnetic resonance in single crystals of hexagonal NiMn${\mathrm{O}}_3$ has shown that the magnetic anisotropy is axial and the easy direction of magnetization lies in the basal plane. The magnetic anisotropy field $\frac{2K}{M}$ equals 5.2×${10}^4$ gauss, corresponding to an anisotropy energy of 2.6×${10}^6$ ergs/${\mathrm{cm}}^3$. Resonance could not be observed at any orientation in single crystals of the isomorphous compound CoMn${\mathrm{O}}_3$.