Reference : Does the orbital degeneracy play any role in the high thermopower of lamellar cobaltites?
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
http://hdl.handle.net/2268/140324
Does the orbital degeneracy play any role in the high thermopower of lamellar cobaltites?
English
Pollet, M. [Institut de Chimie de la Matìre Condensáe de Bordeaux (ICMCB)-CNRS, Universitá de Bordeaux i, 87 Avenue du Dr A. Schweitzer, F-33608 Pessac, France]
Doumerc, J. P. [Institut de Chimie de la Matìre Condensáe de Bordeaux (ICMCB)-CNRS, Universitá de Bordeaux i, 87 Avenue du Dr A. Schweitzer, F-33608 Pessac, France]
Guilmeau, E. [CRISMAT-ENSICAEN Laboratory, UMR CNRS 6508, 6 Bd. Maráchal Juin, 14050 Caen Cedex, France]
Grebille, D. [CRISMAT-ENSICAEN Laboratory, UMR CNRS 6508, 6 Bd. Maráchal Juin, 14050 Caen Cedex, France]
Fagnard, Jean-François [Université de Liège - ULiège > Dép. d'électric., électron. et informat. (Inst.Montefiore) > Capteurs et systèmes de mesures électriques >]
Cloots, Rudi [Université de Liège - ULiège > Département de chimie (sciences) > LCIS - GreenMAT >]
2007
Journal of Applied Physics
American Institute of Physics
101
8
Yes (verified by ORBi)
International
0021-8979
Melville
NY
[en] Bismuth compounds ; Cobalt compounds ; Electron correlations ; Electronic properties ; Seebeck coefficient ; Thermoelectric power ; Crystal field theory ; Octahedron distortion ; Orbital degeneracy ; Atomic physics
[en] This article investigates the role of the CoO6 octahedron distortion on the electronic properties and more particularly on the high value of the Seebeck coefficient in the BiCaCoO lamellar cobaltites. Our measurements provide clues indicating that the t2g orbital degeneracy lifting has to be considered to account for the observed high temperature limit of the thermopower. They also provide experimental arguments for locating the a1g and eg′ orbitals levels on the energy scale, through the compression of the octahedron. These results are in agreement with recent ab initio calculation including the electronic correlations and concluding for the inversion of these levels as compared to the expectation from the crystal field theory. © 2007 American Institute of Physics.
http://hdl.handle.net/2268/140324
10.1063/1.2717602

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