Surface microstructure and magnetic properties of laser-processed granular Co-Ag films

Co-Ag films prepared by Pulsed Laser Deposition and showing GMR in the as deposited state, have been irradiated by excimer laser: the chemical and structural modification induced by such treatment have been studied by XPS and by atomic force and electron microscopies. The pulsed laser irradiation favors the nucleation of nanosized Co grains at Ag grain boundaries, resulting in an enhancement of the magnetoresistivity at low fields and low temperature. Indeed, after laser treatment, a doubled field sensitivity (delta GMR/delta H) at T=10K, with respect to the untreated samples, has been observed. The correlation with the observed magnetic properties variations, is discussed.