Giant magnetoresistance in laser-deposited permalloy/Ag multilayers

Abstract

Giant magnetoresistance (GMR) of 3.5% in low fields of about 10 Oe was observed at room temperature in as-prepared laser-deposited Ni80Fe20/Ag (permalloy/Ag) multilayers. Strong columnar growth in combination with preferential sputtering of Ag from the film surface during deposition of Ni80Fe20 layer helps to directly create a discontinuous multilayer structure necessary for high GMR values. The magnetoresistance was found to increase to 5.1% after annealing for just 10 min at 275 degreesC. This increase is attributed to structural relaxation processes such as demixing of the intermixed interfaces, preferential diffusion of Ag to the column boundaries and reduction of structural defects. Pulsed laser deposition appears to be a suitable technique for the preparation of permalloy/Ag films with considerable GMR in a one-step process. (C) 2002 American Institute of Physics.