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An Electronic Model for $CoO_2$ layer based systems: Chiral RVB metal and Superconductivity

G. Baskaran
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Abstract

Takada et al. have reported superconductivity in layered $Na__x CoO_2.yH_2O$ ($T_c \approx5 K$) and more recently Wen et al. in $A_xCoO_{2+δ}$ ($A = Na,K$)(\tc$\approx~31 K$). We model a reference neutral \cob layer as an orbitally non-degenerate spin-\half antiferromagnetic Mott insulator on a triangular lattice and $Na__x CoO_2.yH_2O$ and $A_xCoO_{2+δ}$ as electron doped Mott insulators described by a t-J model. It is suggested that at optimal doping chiral spin fluctuations enhanced by the dopant dynamics leads to a d-wave superconducting state. A chiral RVB metal, a PT violating state with condensed RVB gauge fields, with a possible weak ferromagnetism and low temperature p-wave superconductivity are also suggested at higher dopings.

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G. Baskaran. 2003-04-01. An Electronic Model for $CoO_2$ layer based systems: Chiral RVB metal and Superconductivity. https://doi.org/10.1103/physrevlett.91.097003

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