Initial layer effects in Co-Cr films

Results are reported which indicate the presence of a magnetically soft initial or nucleation layer in RF diode sputtered CoCr films. As a whole, the films have strong perpendicular anisotropy. However, there appears to be an initial layer some 1000-1500 angstroms thick for 1 micron films and its presence is noted in SEM fracture cross-sections, in-plane hysteresis loops, and in rotational hysteresis torque measurements. This layer seems to reverse by in-plane domain wall motion in spite of the dominant perpendicular curling or buckling reversal of the film as a whole. At small fields, the reversal is clearly by domain wall motion involving only a fraction of the volume while at higher fields the reversal is consistent with curling or buckling and involves almost all of the volume.