Structural and magnetoresistive properties of Co/Cu multilayers

Co/Cu multilayers (ML) were thermally evaporated at very low deposition rat es on Si substrates covered with buffer layers of different metals (Ag, Cu, In, Pb, Bi). Structural characterisation of samples was performed by X-ray reflectometry (XRR), X-ray diffraction (XRD) and atomic force microscopy ( AFM). Magnetoresistance measurements were carried out at room temperature u sing a standard four-probe DC method with current in the plane of the sampl e. It seems that a choice of buffer type has no significant effect on the m agnitude of GMR. Since the thickness of single layers is of similar magnitu de as the interfacial roughness in samples we suggest that the observed sma ll value of GMR effect can be attributed rather to the interruption of film continuity and creation of magnetic bridges between Co layers, resulting i n direct ferromagnetic coupling of magnetic films. (C) 2001 Elsevier Scienc e B.V. All rights reserved.