Magnetic properties of hydrogen-arnorphized RCo2Hx (R = 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 g(J)J mu(B) 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 C-dd = 0.5 x 10(-3) (mu(B)/Co)(-2), the value being considerably lower than that for parent RCo, compounds. (c) 2005 Elsevier B.V. All rights reserved.