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Doping effects on the electronic and structural properties of CoO2: An LSDA+U study

Peihong Zhang·Weidong Luo·Vincent H. Crespi·Marvin L. Cohen·Steven G. Louie
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Abstract

A systematic LSDA+U study of doping effects on the electronic and structural properties of single layer CoO2 is presented. Undoped CoO2 is a charge transfer insulator within LSDA+U and a metal with a high density of states (DOS) at the Fermi level within LSDA. (CoO2)$^{1.0-}$, on the other hand, is a band insulator with a gap of 2.2 eV. Systems with fractional doping are metals if no charge orderings are present. Due to the strong interaction between the doped electron and other correlated Co d electrons, the calculated electronic structure of (CoO2)$^{x-}$ depends sensitively on the doping level x. Zone center optical phonon energies are calculated under the frozen phonon approximation and are in good agreement with measured values. Softening of the $E_g$ phonon at doping x ~0.25 seems to indicate a strong electron-phonon coupling in this system. Possible intemediate spin states of Co ions, Na ordering, as well as magnetic and charge orderings in this system are also discussed.

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Peihong Zhang, Weidong Luo, Vincent H. Crespi, Marvin L. Cohen, Steven G. Louie. 2004-03-29. Doping effects on the electronic and structural properties of CoO2: An LSDA+U study. https://doi.org/10.1103/physrevb.70.085108

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