Interlayer Exchange Coupling in Fe/MgO/Fe Magnetic Tunnel Junctions

Authors

T. Katayama, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
S. Yuasa, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
Julian P. Velev, University of Nebraska-LincolnFollow
M. Ye. Zhuravlev, University of Nebraska at Lincoln
Sitaram S. Jaswal, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska at LincolnFollow

Date of this Version

9-2006

Comments

Published in Applied Physics Letters 89, 112503 (2006); DOI: DOI: 10.1063/1.2349321 Copyright © 2006 The American Physical Society. Used by permission. http://link.aip.org/link/?APPLAB/89/112503/1

Abstract

Interlayer exchange coupling (IEC) in fully epitaxial Fe/MgO/Fe (001) tunnel junctions with wedge-shaped MgO layers is measured at room temperature from the unidirectional shift of the Kerr hysteresis loop. It is found that the IEC is antiferromagnetic for small MgO thickness but changes sign at 0.8 nm. Ab initio calculations of IEC show that this behavior can be explained by the presence of O vacancies in the MgO barrier which makes IEC antiferromagnetic for thin barriers. With increasing MgO thickness the resonance contribution to IEC from localized defect states is reduced resulting in the ferromagnetic coupling typical for perfect MgO barriers.