Magnetisation of Thin Films Under Oblique Field Conditions

Magneto-optical measurements have been made of a single-layer film of TbFeCo and a multilayer Pt/Co film both with perpendicular anisotropy. Magnetising fields were applied at angles in the range theta = 0 degrees-60 degrees with respect to the film normal. Switching fields (H-sw) and the time dependence of magnetization were measured as functions of theta. Values of the magnetic viscosity parameter (Lambda) were determined from the time-dependent magnetization measurements. The angular variation of both H-sw and Lambda are given. The distributions of regions of reversed magnetization in the films have been examined by magnetic force microscopy (MFM) and Kerr effect microscopy. The fractal dimensions of these patterns have been determined. In the TbFeCo film the magnetization distributions and fractal dimension change significantly as the obliquity of the magnetising field changes. In contrast, the obliquity of the magnetising field has little effect on the characteristics of magnetised regions of the Pt/Co film. (C) 1998 Elsevier Science B.V. All rights reserved.