Magnetic tunnel junctions for magnetic random access memory applications

Abstract

Magnetic Tunnel Junctions (MTJ) are in the center of a large number of studies in spin polarized transport, because of their potential use in Magnetic Random Access Memory (MRAM) applications. The most commonly used tunnel junction is composed of an aluminium-oxide as a tunnel barrier and presents very interesting tunnel magnetoresistance (TMR) of about 40%. Nevertheless, this barrier needs an oxidation step and has a large resistance, which is not suitable for electronic devices. Thus a MTJ with an alternative ZnS barrier grown by sputtering on Si(111) substrate at room temperature is presented here with the following structure: Fe 6 nmCu 30 nm(CoFe) 1.8 nmRu 0.8 nm(CoFe) 3 nmZnS x (CoFe) 1 nmFe 4 nmCu 10 nmRu 3 nm. The hard magnetic bottom 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. This alternative barrier is most suitable for electronic devices and we will discuss its possible application in MRAM.