Magnetic Structure of Ground and Field Induced Ordered States of Low-Dimensional γ-CoV2O6

Abstract

The structural and magnetic properties of γ-CoV2O6 low-dimensional magnetic oxide have been investigated with an emphasis on its magnetic structure. Our main results have been obtained by powder neutron diffraction measurements carried out under magnetic fields of 0, 0.52, and 1 T, corresponding to the antiferromagnetic, ferrimagnetic, and ferromagnetic configurations of the magnetic moments. The magnetic moments are not collinear, but lie mostly along the b direction (i.e., inside structural edge-sharing CoO6 chains), which corresponds to the experimental easy magnetization axis. In the ground state, the moments are ferromagnetically ordered along the b and c directions, and antiferromagnetically ordered along a. The ferromagnetic sheets (bc plane) containing the chains are separated by nonmagnetic sheets containing VO6 octahedra and VO4 tetrahedra. The ground state magnetic structure can be described in a (4a, 2b, c) supercell using two antiferromagnetic propagation vectors kAF1 = (1/2, 0, 0) and kAF2 = (1/4, 1/2, 0). The ferri- and ferro-magnetic structures are characterized by kFi = (1/3, 0, −1/3) and k = (0, 0, 0) propagation vectors, respectively. These results are in agreement with macroscopic magnetic measurements performed on single crystals.