Inverse giant magnetoresistance in CoFe/Tb multilayer with perpendicular magnetic anisotropy

Abstract

We detected inverse giant magnetoresistance (GMR) in a multilayer of Ta (4 nm)/[Tb (1.6 nm)/CoFe (1.2 nm)](5)/Cu (3 nm)/[CoFe (1.2 nm)/Tb (0.6 nm)](5)/Ta (4 nm); both the bottom [Tb (1.6 nm)/CoFe (1.2 nm)](5) and top [CoFe (1.2 nm)/Tb (0.6 nm)](5) layers revealed a perpendicular magnetic anisotropy. Furthermore, depending on the Tb layer thickness, we confirmed the magnetization of the bottom CoFe layer to be either parallel or antiparallel to the applied field. Hence, the GMR behavior could be controlled by tuning the perpendicular magnetic anisotropy, i.e., it was switchable from inverse to normal GMR or from normal to inverse. Changes in GMR occurred at a compensation composition of CoFe and Tb for which no magnetization was observed due to antiferromagnetic cancellation of the Tb and CoFe moments. (C) 2011 American Institute of Physics. [doi:10.1063/1.3565197]