In order to clarify the influence of the impurities in the sputtering atmosphere on the microstructure and the giant magnetoresistance (GMR) properties of nanogranular thin films, Co-Cu alloy films were prepared on quartz substrates at room temperature under the different purity of the sputtering atmosphere by changing the base pressure, 10-11 Torr extremely clean process (XC) and 10-7 Tonlower grade process (LG). The correlation between the microstructure and the GMR of films after an annealing procedure is discussed. As results, we found that; (1) A Co-rich phase combined with oxygen was formed at grain boundary in the films as deposited under the LG process; (2) the gradual progress of the grain growth of precipitates with increasing annealing temperature was observed in the XC-processed films, while the coarse grain growth of the matrix phase, resulting in the abrupt change of magnetoresistance occurred in the LG-processed films. We conclude that regulated impurity concentration in the films is an essential parameter to control the precipitation process from the supersaturated solid solution and to realize the desirable microstructure of the nanogranular GMR thin films.
ASJC Scopus subject areas
- Physics and Astronomy(all)