MAGNETIC-PROPERTIES OF NDCO3 AND ITS GAMMA-PHASE HYDRIDE NDCO3H4.1

Magnetization measurements have been carried out for an aligned powder sample of NdCo3 and for an isotropic sample of the hydride NdCo3H4.1. NdCo3 is a ferromagnet with T(c) = 381 K and exhibits a spin reorient ation transition of easy direction from the basal plane to the c axis in the temperature range 220-255 K. NdCo3 shows a field-induced phase transition in low fields below 0.7 T along the c axis from the colline ar to non-collinear structure at temperatures below 115 K. NdCo3H4.1 i s an anti-ferromagnet with T(N) = 214 K and exhibits a metamagnetic tr ansition to the ferromagnetic structure in applied magnetic fields. Th e transition field of NdCo3H4.1 is significantly decreased compared wi th the hydride with non-magnetic Y instead of Nd by the positive excha nge field acting on the Co sublattice from the Nd sublattice.