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Spin-Polarized Density of States and Electron Tunnelling from the CO/Al2O3 Interface

Published online by Cambridge University Press:  10 February 2011

D. Nguyen-Manh ,
E.Yu. Tsymbal ,
D. G. Pettifor ,
C. Arcangeli ,
R. Tank ,
O. K. Andersen  and
A. Pasturel
D. Nguyen-Manh
Affiliation:
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
E.Yu. Tsymbal
Affiliation:
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
D. G. Pettifor
Affiliation:
Department of Materials, University of Oxford, Parks Road, Oxford OX1 3PH, U.K.
C. Arcangeli
Affiliation:
Max-Plank-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany.
R. Tank
Affiliation:
Max-Plank-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany.
O. K. Andersen
Affiliation:
Max-Plank-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569, Stuttgart, Germany.
A. Pasturel
Affiliation:
Physique Numérique des Systèmes Complexes, EP-96, CNRS, BP 166, 38042 Grenoble Cedex, France.
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Abstract

In order to elucidate the mechanism of spin-polarized electron tunneling in thin-film ferromagnet-insulator junctions, self-consistent band structure calculations of the CO/Al2O3 interface have been performed using a new LMTO technique. Since the results of the calculations are very sensitive to the distance between the Co and Al planes, we have minimised the total energy with respect to this distance. Our calculations show that at the Fermi energy a strong bonding between the 3d-electrons of Co with the sp-electrons of Al at the interface can have an important influence on the spin polarization of the layer-projected density of states (LPDOS) of inner Al and O layers. Since the Fermi energy lies within the minority-spin d-band of Co but above the majority-spin d-band, the sp-d bonding results in a smaller LPDOS of the minority-spin electrons of the interfacial Al layers in comparison to that of the majority-spin electrons. This asymmetry in the LPDOS extends to the inner Al2O3 layers implying a positive spin polarization of the tunneling density of states. The result is consistent with experimental observations on tunnelling from cobalt through alumina where positive values of the spin polarization of the tunnelling current were measured.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 492: Symposium S – Microscopic Simulation of Interfacial Phenomena in Solids… , 1997 , 319
Copyright
Copyright © Materials Research Society 1998

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References

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