INFLUENCE OF HYDROGENATION ON MAGNETIC ANISOTROPY OF R_2Fe_(17) SINGLE CRYSTALS

摘要

The magnetocrystalline anisotropy of R_2Fe_(17) (R = Gd, Tb, Er) and their hydrides are studied by analyzing magnetization curves of single crystal like samples in the temperature range 4.2-300 K in magnetic fields up to 140 kOe. No noticeable influence of hydrogenation on magnetic anisotropy in the Gd_2_Fe(17) has been found. An easy-plane to easy-cone transition was detected for Tb_2Fe_(17)H_3 single crystal. The hydrogenation leads to the disappearance of the transition of FOMP type in Er_2Fe_(17)H_3 and to the increase of the field of the magnetic anisotropy. The obtained results are discussed on the basis of a model taking into account the electrostatic interaction of the quadrupolar moment of the asymmetric 4f shell with the electric field gradient. It is established that the orientation of the quadrupolar moment of the asymmetric 4f shell of the rare earth ion with respect to the direction of the resulting magnetic moment of 4f electrons plays an important role.