Effect of the CoZr/Cu interface quality on the magnetoresistance behavior in a spin-valve sandwich (CoZr/Cu/Co)

The magnetoresistance (MR) and the saturation resistivity (rho (s)) are inv estigated at 300 K in [Co98Zr2(t(CoZr)(Angstrom))/ Cu(28 Angstrom)/Co(25 An gstrom)] thin films grown by RF diode sputtering. The highest value of tran sverse MR is obtained along the easy axis and the MR curve was saturated in a magnetic field of 100 Oe at room temperature. X-ray diffraction measurem ents (XRD) at low angles point out clearly the important interfacial roughn ess increase observed in magnetic structures with CoZr magnetic layers comp ared to (Co/Cu) basic multilayers. The MR behavior versus the CoZr magnetic layer thickness (t(CoZr)) exhibits a maximum (approximate to3.6%) at t(CoZ r) = 30 Angstrom, over which a significant decrease is observed, rho (s) de creases with increasing t(CoZr) up to 30 Angstrom, and increases with incre asing thickness toward the value of the measured CoZr thicker layer (approx imate to 40 mu Omega cm). The representation of the CoZr/Cu interface by a mixed zone in the Johnson-Camley semi-classical model reproduces well the e xperimental results of MR and rho (s) versus t(CoZr), confirming thus the i mportant role of interface quality on the electronic transport properties. (C) 2001 Elsevier Science B.V. All rights reserved.