Giant magnetoresistance and structural properties in Co/Cu/Co sandwiches with Si and Cr buffer layers

Abstract

Cobalt 5.5 nm/Cu 3 nm/Co 5.5 nm sandwiches with Si and Cr buffer layers were prepared by ultra-high vacuum electron beam evaporation. A large in-plane anisotropy of the giant magnetoresistance (GMR) effect was found in Si buffered sandwiches when the buffer layer thickness was equal to or larger than 0.9 nm. In the easy axis, the GMR effect reached a value of 5.5% with a high field sensitivity of approximately 0.7%/Oe, while in Cr-buffered Co/Cu/Co sandwiches, the GMR effect showed only in-plane isotropic properties with a maximum GMR value of 6%. The XRD spectrum and HRTEM image revealed that there exists a Co 2Si compound between the Si buffer and the lower Co magnetic layer. All these results indicate that the anisotropic GMR effect in Si-buffered sandwiches results from the cobalt silicide between the Si buffer and the lower Co magnetic layer.