Characterization and giant magnetoresistance effect in cobalt-silver granular films formed by MEVVA implantation

Cobalt-silver granular thin films exhibiting giant magnetoresistance (GMR) effect were formed by Co implantation into Ag using a metal vapor vacuum ar e (MEVVA) ion source. The magnetic field dependence and the temperature var iation of the GMR effect and their relation with the processing conditions were studied and discussed in conjunction with results of Rutherford backsc attering spectrometry, atomic force microscopy and magnetic force microscop y (MFM). For the best sample obtained in this study, the magnitude of the G MR effect measured at a magnetic field strength of 7.6 kOe increases from a bout 1% at room temperature to over 7% at 20 K. The coercive field H-C in t he perpendicular-to-film direction determined from GMR measurements showed an anomalous temperature variation that shows a maximum value at around 240 K and decreases with decreasing temperature from 240 to 20 K. The domain s tructures of the implanted granular films revealed by MFM images exhibit a very different feature compared with those of sputter deposited Co-Ag granu lar films. (C) 1999 Elsevier Science B.V. All rights reserved.