Tunnel magnetoresistance in magnetic tunnel junctions with a ZnS barrier

We report on the junction magnetoresistance in magnetic tunnel junctions of the hard-soft type with magnetic layers separated by a ZnS barrier. The ha rd magnetic bottom electrode consists of an artificial antiferromagnetic st ructure in which the rigidity is ensured by the antiferromagnetic exchange coupling between two FeCo layers through a Ru spacer layer. The samples wer e grown by sputtering on Si (111) wafers at room temperature and have the f ollowing structure: Fe6 nmCu30 nm(CoFe)(1.8 nm)Ru-0.8 nm(CoFe)(3 nm)ZnSx(Co Fe)(1 nm)Fe4 nmCu10 nmRu3 nm. The square tunnel elements, with lateral size s of 10, 20, 50, and 100 mum, exhibit typical tunnel resistance of 2-3 k Om ega mum(2) and nonlinear zero field current-voltage (J-V) variation. The mo st interesting result is the observation of junction magnetoresistance of a bout 5% at room temperature with a 2 nm thick ZnS barrier. (C) 2001 America n Institute of Physics.