Enhancement of MR ratios with Ag capping layer in (100) oriented Ni-Fe/Cu/Co trilayers

Abstract

This paper reports enhancement of magnetoresistance in spin-valve trilayers by improving specular reflectivity of conduction electrons at the film surface of the metal capping layer. The samples were epitaxially grown on MgO(100) by ultrahigh vacuum deposition. The MR ratio of the MgO/Pt(10 nm)/Cu(5 nm)/Ni-Fe(5 nm)/Cu(2.8 nm)/Co(5 nm)/Cu(1.2 nm) film increased from 3.9% to 5.4% by the addition of a 3 nm-thick-Ag capping layer. The enhancement of MR ratio may be attributed to the increase of specular reflection of conduction electrons at the Ag surface. Co layer thickness dependence of the MR ratio in the spin-valves also supports this interpretation.