A MICROSTRUCTURAL STUDY OF ANNEALED TI CO/CU/CO/MNFE/TI SPIN-VALVE FILMS/

Spin-valve properties are adversely affected by heat treatments and in order to study this effect, microstructural analyses of Ti/Co/Cu/Co/M nFe/Ti spin-valve films annealed at 225 and at 290 degrees C have been performed. Whereas the lower temperature tends to optimize the giant magnetoresistance (GMR) ratio, the higher temperature induces a signif icant decrease in the GMR ratio (from 7.5% to 5.2%). High resolution e lectron microscopy studies have explained this result as being due to the formation of a TiCo alloy at the Ti/Co interface and to a decrease in the thickness of the sense layer. No significant modification of e ither the Co/Cu or the Cu/Co interfaces has been observed. (C) 1998 Am erican Institute of Physics.