MICROMAGNETIC PROPERTIES AND DOMAIN DYNAMICS OF COPT THIN-FILMS

We have studied the magnetization reversal processes of thin CoPt allo y films by using domain pattern analysis techniques. By means of polar ization microscopy based on the polar magnetooptic Kerr effect we were able to investigate static and dgnamic properties of the magnetizatio n 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 occurenc e of local demagnetizing fields is the key to describe the observed re versal processes. Furthermore we found evidence for fractality in the magnetic domain pattern. The motion of domain walls is characterized b y wall jaggedness, which obeys scaling laws predicted by the theory of directed percolation.