Effect of oxygen vacancies on spin-dependent tunneling in Fe/MgO/Fe

Authors

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

Date of this Version

2-12-2007

Comments

Published in APPLIED PHYSICS LETTERS 90, 072502 2007. © 2007 American Institute of Physics. Permission to use.

Abstract

First-principles calculations based on density functional theory are used to elucidate the effect of O vacancies, forming F centers, on spin-dependent tunneling in Fe/MgO/Fe(001) magnetic tunnel junctions. O vacancies produce occupied localized s states and unoccupied resonant p states, which is consistent with available experimental data. The authors find that O vacancies affect the conductance by nonresonant scattering of tunneling electrons causing a substantial reduction of tunneling magnetoresistance (TMR). Improving the quality of the MgO barrier to reduce O vacancy concentration would improve TMR in these and similar junctions.