Effect of interface states on spin-dependent tunneling in Fe/MgO/Fe tunnel junctions

Authors

Kirill D. Belashchenko, University of Nebraska - LincolnFollow
Julian P. Velev, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow

Date of this Version

10-1-2005

Comments

Published in Physical Review B, 72, 140404 (1 October 2005)
Copyright © 2005 The American Physical Society. Used by permission
URL: http://link.aps.org/abstract/PRB/v72/e140404
doi:10.1103/PhysRevB.72.140404

Abstract

The electronic structure and spin-dependent tunneling in epitaxial Fe/MgO/Fe(001) tunnel junctions are studied using first-principles calculations. For small MgO barrier thickness the minority-spin resonant bands at the two interfaces make a significant contribution to the tunneling conductance for the antiparallel magnetization, whereas these bands are, in practice, mismatched by disorder and/or small applied bias for the parallel magnetization. This explains the experimentally observed decrease in tunneling magnetoresistance (TMR) for thin MgO barriers. We predict that a monolayer of Ag epitaxially deposited at the interface between Fe and MgO suppresses tunneling through the interface band and may thus be used to enhance the TMR for thin barriers.