Body centered cubic buffer layers for enhanced lateral grain growth of Co/Cu multilayers

Abstract

The effect of buffer layers (BLs) on metallurgical microstructure and giant magnetoresistance of Co/Cu multilayers fabricated on them is discussed. The lateral grain size and the magnetoresistance (MR) ratio of multilayers are generally enlarged with changing the chemical composition of BLs toward a limiting concentration, within the range where the solid solution of body-centered-cubic (bcc) structure is formed. A guiding principle for material research for the BLs, which realize flat interfaces with large lateral grain size in the multilayers, is deduced from the correlation between the MR ratio of the multilayers and the surface energy of bcc BLs: the difference between the surface energy of BL (γS) and the interfacial energy (γSL) in Young–Dupré’s equation (cos θ=(γS−γSL)/γL) should agree with the surface energy of Co layer (γL), which is deposited first on the BL.