MICROSCOPIC AND MACROSCOPIC INHOMOGENEITY OF MAGNETIZATION AND ANISTROPY IN AMORPHOUS RARE EARTH-TRANSITION METAL-FILMS

Amorphous Gd/Co and Gd/Co/Mo‐films are investigated by measuring the field dependence of the susceptibility. This allows a determination of the value and sign of the perpendicular uniaxial anisotropy as well as the value of the effective ripple stray field. The measurements are made at spots of 50 to 100 μm diameter, allowing one to scan the film surface. Measurements from a spot on the film surface and at the opposing spot on the film‐glass substrate interface are performed simultaneously. In this way the anisotropy at two related points on both surfaces of the film can be compared. In general the results show the existence of a ripple stray field which can be accounted for by inhomogeneities in the amorphous films. The perpendicular anisotropy at the free film surface is always lower than the perpendicular anisotropy at the film‐substrate interface. In some cases the magnetization at the film surface is in‐plane, while at the substrate the magnetization is out‐of‐plane. The reduction of the perpendicular anisotropy is an ageing effect due to oxidation. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA