TEMPERATURE-VARIATION OF THE MAGNETORESISTANCE IN COBALT-ENHANCED SPIN-VALVE STRUCTURES

We have conducted a survey of the temperature variation of the magneto resistance in a series of FeMn exchange-biased spin-valve structures. These permalloy-based samples were prepared in an ion-beam sputtering system and feature Co layers inserted at the interfaces with the Cu sp acer layer to enhance the interfacial spin-dependent scattering. Typic al values for the MR are 4.0% at 295 K and 8.4% at 8 K (sample with 15 Angstrom Co thickness). A control sample with no cobalt showed MR val ues of 1.3% and 4.3% for those same temperatures. Both the MR ratio an d the un-normalized magnetoresistive change Delta R are plotted vs tem perature. The MR ratio for the cobalt-enhanced samples exhibits nearly linear decrease with rising temperature. The sample with no cobalt ex hibits a temperature variation deviating substantially from linearity, with an upward curvature. The temperature dependence for the MR in th ese spin valves is examined in the light of interchannel spin-mixing a nd intrachannel scattering. (C) 1997 American Institute of Physics.