Magnetic properties of hydrogen-amorphized RCo2Hx (RÂ =Â Gd, Tb, Dy, Ho, Er, Tm and Y) alloys

High-field magnetization curves and temperature dependences of the magnetization have been measured for RCo2Hx alloys amorphized by hydrogen treatment (R = heavy rare earths and yttrium). It was found that am-RCo2Hx are ferrimagnets with a strong Co-Co and a relatively weak R-Co exchange interaction. The compensation point observed in the M(T) curves shifts systematically to lower temperatures with increasing atomic number of the R elements. Both magnetic moment and compensation temperature depend on the amorphization temperature, which indicates a metastable and heterogeneous structural state of the amorphous hydrides. For the compositions with anisotropic R ions (Tb, …, Tm) the calculated magnetic moment of the R subsystem appears to be considerably lower than the value gJJ μB for corresponding rare earth ions, probably due to a non-collinear magnetic structure of the R subsystem. From the pressure effect on the magnetization measured for am-HoCo2H3, the magnetoelastic coupling constant is estimated as Cdd = 0.5 × 10−3 (μB/Co)−2, the value being considerably lower than that for parent RCo2 compounds.