Magnetic instabilities in Er1-xYxCo3Er1-xYxCo3 studied by NMR

The field dependence of 59Co NMR in ferrimagnetic Er1-xYxCo3Er1-xYxCo3 was measured up to 8 T at 4.2 K. For pure ErCo33 in fields perpendicular to the c axis the resonance frequencies change discontinuously between 2 and 3 T due to a field induced metamagnetic transition. The transition is characterized by rotations of Er and Co magnetic moments away from the easy c-axis. The angles between the Co moments and the c axis at x=0.1x=0.1 are obtained. The easy axis is found to be along the c axis for x=0x=0 and 0.1, and inclined from the c axis for x=0.3x=0.3 and 0.5.