Perpendicular magnetization of CoZr/Pt multilayers

Abstract

Recently, the perpendicular magnetization of tunnel junctions has been proposed as a way to reduce the size of spin-transfer torque random access memories. In order to determine the free layer of a magnetic tunnel junction, we present a Co(90)Zr(10) alloy that is expected to have a higher polarization than any other soft magnet. At a thickness of 0.6 nm, CoZr successfully forms a perpendicular magnetization because of the interfacial anisotropy on the CoZr/Pt interfaces. Unlike the Co/Pt multilayer, the CoZr/Pt multilayer shows magnetization recovery following 1.5-T field cooling after 300 A degrees C annealing because Zr insertion prevents the formation of a CoPt alloy. This work proposes CoZr as a free-layer candidate for magnetic tunnel junctions due to its advantages of lower switching current and higher thermal stability.