Superconductivity in NaxCoO2 yH2O due to Charge Fluctuation

A new mechanism of superconductivity due to charge fluctuation in the newly discovered Co-based oxide is proposed. A single-band extended Hubbard model on a triangular lattice is studied within the random phase approximation. f -wave triplet superconductivity is stabilized in the vicinity of charge–density–wave instability, which is in sharp contrast to the square-lattice case. The physical origin of the realization of the f -wave triplet state as well as its relevance to experiments are discussed.

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