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