HIGH-FIELD MAGNETIZATION OF SINGLE-CRYSTAL GAMMA-PHASE HYDRIDES HOCO3H4.3 AND ERCO3H4.2

Magnetization measurements have been performed for single-crystal gamma-phase hydrides ErCo3H4.2 and HoCo3H4.3 in high magnetic fields up to 40 T. Both the hydrides become antiferromagnetic with a Neel temperature of about 200 K due to the appearance of the negative Co-Co intersite exchange interaction after hydrogenation. As a result of the significant weakening of the R-Co intersublattice exchange interaction, the R and Co sublattices behave quite independently: With increasing magnetic field along the c-axis, the antiferromagnetic ordering of the R sublattice breaks at first and then the metamagnetic transition occurs at a higher field. After the transition the spin arrangement of R and Co becomes almost aligned. This transition field decreases with increasing temperature and becomes zero at the Neel temperature.