Co-existing magnetic phases of nano-scaled granular Co20Cu80 alloy system

Nano-scaled granular Co20Cu80 alloy was prepared by mechanical alloying technique and the resulting powder was consolidated by hot pressing. Structural evolution and magnetization behavior were examined by using X-ray diffractometry and magnetization measurement by VSM and SQUID magnetometer. XRD results and variation of magnetization with processing time show the formation of a supersaturated fcc solid solution. Magnetization of the alloy could be interpreted as a mixture of ferromagnetic and superparamagnetic components, resulting from the non-uniform size distribution of magnetic clusters in the Cu matrix. With increasing temperature superparamagnetic component becomes the dominant contributor. Maximum MR ratio of the hot pressed specimen was about 3.3% at room temperature, under a maximum magnetic field of 10 kOe.