Amorphous GdCoCr Films for Bubble Domain Applications

Amorphous GdCoCr films of various composition ratios made by rf bias sputtering are investigated for their applicability as bubble domain supporting materials. Film compositions around Gd0.13Co0.65Cr0.22have temperature-insensitive magnetizations between 240 K and 350 K with Tcompnearly 120 K and Tcnearly 630 K. Reduction of the Cr content from 21.8 to 20.3 at. percent causes an increase of the magnetization by a factor of three. Thermal cycling of these films between 290 K and 570 K does not change the magnetization noticeably, nor does annealing for up to six days at 520 K. The films are found to be very susceptible to contamination by the residual oxygen present in the vacuum chamber during sputtering. Films contaminated with 3 to 13 at. percent oxygen have coercivities around 800 A/m (10 Oe), whereas films which were oxygen-free according to microprobe investigations show coercivities less than 80 A/m (1 Oe).