Inverted and biased loops in amorphous Gd-Co films

Amorphous Gd-Co films sputtered at substrate biases ≤100V showed compensation temperature differences of about 100°C between the film-glass (FG) and film-air (FA) surfaces, as measured by Kerr rotation. The films exhibited normal as well as inverted Kerr and Hall loops, but throughout the temperature range between compensation temperatures either the FG or FA surface, but not both, showed inverted Kerr loops. Inversion temperatures were found at which the inverted loop property was transferred from one film surface to the other. Biased loops were obtained from inverted loops by reducing the field amplitude in one polarity. The bias field, HB, was identified as the effective field of exchange-coupled Gd-Rich and Co-rich layers. By the use of HBdata the interlayer wall energy density was estimated to be 0.9 ±0.2 ergs cm^-2.