Anisotropic Distribution of Atomic Pairs Induced by the Preferential Resputtering Effect in Amorphous Gd-Fe and Gd-Co Films

Abstract

Mössbauer effect and X-ray diffraction of amorphous Gd-Fe films show that isolated Gd atoms are preferentially resputtered and a non-uniform distribution of Gd atoms is induced in amorphous Gd-T (T=3d transition metal) films prepared by a sputtering method with negative bias. The resputtering effect of isolated Gd atoms produces anisotropic distributions of T-T, Gd-T and Gd-Gd pairs in Gd-T films. The difference between the numbers of T-T pairs parallel and normal to the film amounts to 1020∼1021 pairs/cm3. This number of T-T pairs is appropriate to account for the oserved anisotropy of amorphus Gd-Co films. It is coucluded that the anisotropic distribution of atomic pairs is the most important origin of the magnetic uniaxial anisotropy induced by bias sputtering.