Heat treatment effects of CoCr sputtered films

Thermomagnetic analyses of RF-sputtered Co/sub 84/Cr/sub 16/ and Co/sub 78/Cr/sub 22/ thin films are reported. It is found that, when CoCr film is heated lower than the HCP to FCC transformation temperature, M/sub s/ drops substantially after holding at a constant temperature, and M/sub s/ at room temperature decreases after one cycle of heat treatment. This is due to Cr redistribution from the Cr-rich region of the film. When CoCr is heated higher than the HCP to FCC transformation temperature, M/sub s/ jumps sharply after holding at a constant temperature. This is due to the formation of an FCC phase with high M/sub s/ at higher temperature. A study of the angular dependence of coercivity indicates that the demagnetization mechanism of as-sputtered film seems to be an incoherent rotation mechanism while for the heat-treated film it may be domain wall motion or another combined mechanism. The perpendicular anisotropy in the Cr film may be connected with the existence of a highly Cr segregated region as well as c-axis alignments.<
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