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Surface Band Gaps and Superexchange Interaction in Transition Metal Oxides

Published online by Cambridge University Press:  15 February 2011

J. J. M. Pothuizen ,
O. Cohen  and
G. A. Sawatzky
J. J. M. Pothuizen
Affiliation:
Surface Science, Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, jjmp@vsfl.phys.rug.nl
O. Cohen
Affiliation:
Surface Science, Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, jjmp@vsfl.phys.rug.nl
G. A. Sawatzky
Affiliation:
Surface Science, Materials Science Center, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands, jjmp@vsfl.phys.rug.nl
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Abstract

In this paper, we discuss the change in the band gap of charge transfer insulators for different surface terminations. We have calculated the Madelung potential of the unreconstructed (100) surfaces of the rocksalt structured TM-O compounds (TM = Mn, Fe, Co and Ni). We also considered possible step defects on a (100) surface. The presented results are calculated in both the purely ionic case (TM2+O2−) and in the strong ligand p - cation 4s, phybridization (TM1+O1−) case. In both cases the charge transfer gap, Δ, for the surface is reduced compared to the bulk value. As a consequence of this reduction there is a large increase of the surface superexchange interaction, Jsur, and a decrease of the band gap.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 401: Symposium G – Epitaxial Oxide Thin Films II , 1995 , 501
Copyright
Copyright © Materials Research Society 1996

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