Spin reorientation and magnetic structure of HoCo12B6 ferrimagnetic compound

The magnetic phase diagram is determined by combining magnetization measurements, ac susceptibility and neutron diffraction. The crystal and magnetic structures are also investigated. The HoCo12B6 compound exhibits ferrimagnetic behavior below TC = 147 K. Two antiferromagnetically coupled sublattices cancel out at the compensation temperature TComp = 46 K. HoCo12B6 undergoes a spin reorientation transition at TSR = 76 K; the easy magnetization axis changes from axial to basal plane upon heating. The magnitude of the magnetic moments and their orientation are described and discussed. It is revealed that HoCo12B6 compound exhibits a commensurate magnetic structure below TSR and an incommensurate one slightly above TSR. Significantly different magnetic moments have been observed on the two Co crystal sites, a very low magnetic moment of 0.14 μB being refined on the Co 18 g position. In addition, the second order crystal electric-field parameter at the rare-earth site is determined. This result is discussed and used to explain the observed spin reorientation transition by a competition between the Co and Ho sublattice anisotropy.