Tunnel magnetoresistance in magnetic tunnel junctions with a ZnS barrier

Abstract

We report on the junction magnetoresistance in magnetic tunnel junctions of the hard–soft type with magnetic layers separated by a ZnS barrier. The hard magnetic bottom electrode consists of an artificial antiferromagnetic structure in which the rigidity is ensured by the antiferromagnetic exchange coupling between two FeCo layers through a Ru spacer layer. The samples were grown by sputtering on Si (111) wafers at room temperature and have the following structure: Fe6 nmCu30 nm(CoFe)1.8 nmRu0.8 nm(CoFe)3 nmZnSx(CoFe)1 nmFe4 nmCu10 nmRu3 nm. The square tunnel elements, with lateral sizes of 10, 20, 50, and 100μm, exhibit typical tunnel resistance of 2–3 kΩ μm2 and nonlinear zero field current–voltage (J–V) variation. The most interesting result is the observation of junction magnetoresistance of about 5% at room temperature with a 2 nm thick ZnS barrier.