Tunnel magnetoresistance in magnetic tunnel junctions with ZnS barrier

A first experimental evidence of a significant tunneling magnetoresistance signal of about 5% at 300 K for a magnetic tunnel junction consisting of ha rd and soft magnetic layers separated by a 2 nm ZnS semiconducting barrier is reported. The samples have been grown by sputtering on Si(111) substrate at room temperature and have the following structure: Fe6 nmCu30 nmCoFe1.8 nmRu0.8 nmCoFe3 nmZnSxCoFe1 nmFe4 nmCu10 nmRu3 nm. The hard magnetic botto m electrode consists of the artificial antiferromagnetic structure in which the rigidity is ensured by the antiferromagnetic exchange coupling between two FeCo layers through a Ru spacer layer. Barrier impedance scanning micr oscope (BISM) measurements reveal a good homogeneity of the barrier thickne ss. Electric transport measurements over square tunnel elements with latera l sizes between 3 and 100 mum, exhibit a typical tunnel current-voltage var iations and tunnel resistance of 2-3 k Ohm mum(2) with small variations whi ch never exceed a factor of 2, which is in good agreement with the BISM res ults. This good reproducibility of the junctions is very promising for MRAM s and transistors applications. (C) 2001 American Institute of Physics.