GIANT MAGNETORESISTANCE OF COBALT SILVER METASTABLE ALLOYS PREPARED BY SPUTTERING AND MECHANICAL ALLOYING

We report the first observation of giant magnetoresistance (16.0% at 5 K) in metastable bulk cobalt-silver alloys prepared by mechanical all oying. The magnetic and electrical transport properties in giant-magne toresistive inhomogeneous cobalt-silver films prepared by both sputter ing and mechanical alloying are compared. The sputtered material consi sts of two distinct magnetic phases: large clusters which dominate the magnetization and magnetoresistive processes at room temperature, bet ween which cooperative behaviour is observed; and small clusters which dominate the magnetization below 10 K, but make only a minor contribu tion to the magnetoresistance.