MICROMAGNETIC PROPERTIES AND DOMAIN DYNAMICS OF COPT THIN-FILMS

We have studied the magnetization reversal processes of thin CoPt alloy films by using domain pattern analysis techniques. By means of polarization microscopy based on the polar magnetooptic Kerr effect we were able to investigate static and dgnamic properties of the magnetization reversal processes in Co28Pt72 alloy samples in the thickness range from 40 to 300 Angstrom. In correlation to the film thickness we found a transition from domain wall motion dominated reversal to nucleation dominated behavior. Our micromagnetic model reveals that the occurence of local demagnetizing fields is the key to describe the observed reversal processes. Furthermore we found evidence for fractality in the magnetic domain pattern. The motion of domain walls is characterized by wall jaggedness, which obeys scaling laws predicted by the theory of directed percolation.