Magnetic and magnetoelastic aftereffect in the intermetallic Sm(Fe0.4Co0.6)(2) compound containing hydrogen impurity

The relaxation of magnetization and magnetoelastic deformation is investiga ted in a cubic Sm(Fe0.4Co0.6)(2) ferromagnet containing a small amount of s pontaneously absorbed hydrogen. In the compounds of this type, a significan t local magnetic anisotropy is observed at room temperature, while annealin g in a magnetic field induces a uniaxial anisotropy in the samples. The app earance of the induced anisotropy is caused by hydrogen ordering under the action of magnetoelastic deformation of the lattice and is accompanied by c learly pronounced relaxation processes. It is shown that the aftereffect ob served can be described in terms of the relaxation-time distribution model. The average relaxation time changes exponentially with time, which indicat es the thermally activated nature of the aftereffect. The activation energy determined from the Arrhenius plot is 1.05 eV for the relaxation of magnet oelastic deformation and 1.13 eV for the magnetization relaxation. These va lues of the activation energy are comparable with those determined from the experiments on hydrogen diffusion in metals.