Fully epitaxial Fe/MgO/Fe(001) junctions with nonmagnetic metal layer insertion

Abstract

Fully epitaxial Fe/Ag-wedge/MgO/Fe(001) magnetic tunnel junctions (MTJs) were prepared by using a combination of magnetron sputtering and molecular beam epitaxy, and their magneto-transport properties were investigated for the Ag thickness range of 0-9 monolayer (ML). The large tunneling magnetoresistance (TMR) ratios of up to 160 at room temperature were obtained in the Fe/MgO/Fe region (Ag: 0 ML) after the optimization of the preparation conditions. The finite TMR ratio was observed until the Ag thickness reached 4 ML, although no significant oscillation due to quantum well states (QWS) was seen. This is the first demonstration of TMR in the fully epitaxial MTJs with nonmagnetic metal layer insertion which can potentially create spin-dependent QWS. © 2011 American Institute of Physics.