Aging effects on microstructure and GMR in Au-Co and Au-Co-X (X=Cu,Ni,Fe) bulk alloys

Aging effects on the microstructure and the GMR in Au-Co and Au-Co-X (X=Fe,Ni,Cu) bulk granular alloys have been investigated. TEM observation shows that Co particles are of plate-like type and grow with the aging time. The optimum size for the maximum MR ratio is a length of about 10 nm and a thickness of 0.6 nm. In Au-Co-X (X=Cu,Ni,Fe) bulk alloys, it was confirmed that the maximum value of the MR ratio is about 3.5% at 10 kOe for Au/sub 80/Co/sub 15/Fe/sub 5/ bulk alloy aged at 300/spl deg/C for 1 hr.