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Doping effects on the electronic and structural properties of CoO 2 : An LSDA + U study

Doping effects on the electronic and structural properties of CoO 2 : An LSDA + U study A systematic local spin density approximation ( LSDA ) + U study of doping effects on the electronic and structural properties of single layer CoO 2 is presented. Undoped CoO 2 is a charge transfer insulator within LSDA + U and a metal with a high density of states (DOS) at the Fermi level within LSDA. ( CoO 2 ) 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 ( CoO 2 ) 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 intermediate spin states of Co ions, Na ordering, as well as magnetic and charge orderings in this system are also discussed. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review B American Physical Society (APS)

Doping effects on the electronic and structural properties of CoO 2 : An LSDA + U study

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Publisher
American Physical Society (APS)
Copyright
Copyright © 2004 The American Physical Society
ISSN
1550-235X
DOI
10.1103/PhysRevB.70.085108
Publisher site
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Abstract

A systematic local spin density approximation ( LSDA ) + U study of doping effects on the electronic and structural properties of single layer CoO 2 is presented. Undoped CoO 2 is a charge transfer insulator within LSDA + U and a metal with a high density of states (DOS) at the Fermi level within LSDA. ( CoO 2 ) 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 ( CoO 2 ) 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 intermediate spin states of Co ions, Na ordering, as well as magnetic and charge orderings in this system are also discussed.

Journal

Physical Review B – American Physical Society (APS)

Published: Aug 15, 2004

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