2005 Fiscal Year Final Research Report Summary
The electronic structure of strongly correlated electrons at the surface of transition-metal oxides
| Project/Area Number |
16540330
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Condensed matter physics II
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| Research Institution | Nihon University |
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Principal Investigator |
ISHIDA Hiroshi Nihon University, College of Humanities and Sciences, Professor, 文理学部, 教授 (60184537)
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| Project Period (FY) |
2004 – 2005
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| Keywords | transition metal oxide / electron correlation / strongly correlated electrons / density functional theory / dynamical mean-field theory / quantum Monte Carlo method / embedded Green-function / FLAPW |
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| Research Abstract |
We have investigated the electronic structure of strongly correlated electrons at the surface of transition-metal oxides by a first principles method within the local density approximation (LDA) plus dynamical mean-field theory (DMFT). In the DMFT calculation, the single Anderson impurity problem was solved using the quantum Monte Carlo technique of Hirsch and Fye. We focused on the (001) surfaces of cubic perovskite SrVO_3 for which photoemission measurements were performed recently.
As the surface structure of SrVO_3 is not known, we first considered its ideal cleaved surfaces with both SrO-layer and VO_2-layer terminations. We used the FLAPW total energy code (FLEUR) to determine the relaxations of surface atoms in the normal direction. It was found that the displacements of the O atoms that constitute octahedrons surrounding central V atoms are rather small. For all the structures, we determined the LDA electronic structure of semi-infinite surfaces using the embedded Green function method. Then, the calculated density of states (DOS) projected on the t_<2g> orbitals of an outermost V atom was used as an input to the subsequent DMFT calculations.
For the SrO-layer terminated surfaces, the reduced coordination number of outermost V atoms in the normal direction gives rise to a significant narrowing of the LDA DOS for the d_<xz/yz> bands, which leads to stronger correlation features in the calculated surface quasi-particle spectra than in the bulk. In the case of VO2-layer terminated surfaces, the lack of the local octahedral symmetry at outermost V sites causes substantial changes in the valence electronic structure of the V atoms and results in a considerable rearrangement of t_<2g> valence charge compared to the bulk. This charge transfer among the three t_<2g> orbitals is further promoted by correlation effects.
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Research Products
(3 results)
