NMR study of magnetic structure in α-CoV₂O₆

We have investigated the magnetic structures of ordered phases, appearing in the elevated magnetic field, for the brannerite-type material α-CoV₂O₆ which exhibits the 1/3 magnetization plateau in the intermediate magnetic field. The ⁵¹V-NMR spectra in the ferro-, ferri-, and antiferro-magnetic phases are consistently explained by considering the transferred hyperfine field and the dipolar field from the Co²⁺ magnetic moments on the basis of the previously reported magnetic structures. These results suggest that the superexchange interaction through the Co-O-V-O-Co pathway does not show significant field variation, although the lattice constant is largely changed due to the strong spin-lattice coupling with increasing magnetic field. (author)