Structural and magnetic studies of CoCu granular alloy obtained by ion implantation of Co into a Cu matrix

CoCu granular alloys have been prepared at room temperature using ion impla ntation of Co+ ions into Cu host at 160 keV. The Cu layer has been deposite d on silicon substrate by DC sputtering at room temperature. The as-implant ed and annealed CoCu alloys at different temperatures have been characteriz ed by X-ray diffraction, Rutherford back scattering (RBS) for the structura l properties, resistivity and magnetization measurements for the magneto-tr ansport properties. Magnetization measurements show a classical superparama gnetic behavior as expected for granular alloy. The observation of the gian t magnetoresistance (GMR) at 300 degreesC annealing temperature indicates t he beginning of Co phase decomposition. The decrease of the GMR at high ann ealing temperature is due to the atomic Co and Cu diffusion into Si substra te as supported by X-ray and RES analysis. (C) 2001 Elsevier Science B.V. A ll rights reserved.