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Bias Dependent TMR in Fe/MgO/Fe(100) Tunnel Junctions

Published online by Cambridge University Press:  01 February 2011

Ivan Rungger ,
Alexandre Reily Rocha ,
Oleg Mryasov ,
Olle Heinonen  and
Stefano Sanvito
Ivan Rungger
Affiliation:
[email protected], Trinity College Dublin, School of Physics, College Street, Dublin, N/A, 2, Ireland, 0035316088454
Alexandre Reily Rocha
Affiliation:
[email protected], Trinity College, School of Physics, Dublin, N/A, 2, Ireland
Oleg Mryasov
Affiliation:
[email protected], Seagate Research, Pittsburgh, Pennsylvania, 15222, United States
Olle Heinonen
Affiliation:
[email protected], Seagate Technology, Bloomington, Minnesota, 55435, United States
Stefano Sanvito
Affiliation:
[email protected], Trinity College, School of Physics, Dublin, N/A, 2, Ireland
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Abstract

We calculate from first principles the I-V characteristics of Fe/MgO/Fe(100) tunnel junctions. In particular we compare the zero-bias transmission with self-consistent calculations at finite bias. In the case the magnetizations of the two Fe layers are parallel to each other, at small bias there is a significant contribution to the transmission coming from the minority spin channel. This is due to a sharp resonance in the transmission coefficient close to the Fermi level, originating from a surface state. As a bias exceeding 25 mV is applied, the surface states get out of resonance and the current through the minority spin channel saturates, so that the current flows mainly through the majority channel. The same effect is not present for the antiparallel alignment of the magnetization with the net result of large TMR at low bias, which then saturates for a bias larger than 25 mV.

Keywords

magnetoresistance (transport)electronic structurespintronic
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 941: Symposium Q – Magnetic Thin Films, Heterostructures, and Device Materials , 2006 , 0941-Q01-03
Copyright
Copyright © Materials Research Society 2006

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