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Electronic structure and Fermi surface tolopogy of Na$_x$CoO$_2$

A. Bourgeois·A. A. Aligia·T. Kroll·M. D. Núñez-Regueiro
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Abstract

We construct an effective Hamiltonian for the motion of T2g highly correlated states in NaxCoO2. We solve exactly a multiband model in a CoO6 cluster with electronic occupation corresponding to a nominal Co valence of either +3 or +4. Using the ensuing ground states, we calculate the effective O mediated hopping t=0.10 eV between many-body T2g states, and estimate the direct hopping t'~0.04 eV. The trigonal splitting 3D=0.315 eV is taken from recent quantum chemistry calculations. The resulting effective Hamiltonian is solved using a generalized slave-boson mean-field approximation. The results show a significant band renormalization and a Fermi surface topology that agrees with experiment, in contrast to predictions using the local-density approximation.

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A. Bourgeois, A. A. Aligia, T. Kroll, M. D. Núñez-Regueiro. 2006-10-11. Electronic structure and Fermi surface tolopogy of Na$_x$CoO$_2$. https://doi.org/10.1103/physrevb.75.174518

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