Coexistence of f-wave superconductivity, charge order, and spin antiferromagnetism around nonmagnetic impurities in Na0.33CoO2.1.3H2O

To check whether charge dynamics is responsible for the superconductivity in NaxCoO2.yH2O, we investigate local electronic and magnetic structure around nonmagnetic impurities embedded in this material at x=0.33 in the vicinity of charge instability, by using a phenomenological model within the slave-boson framework including competitions among a square root of 3 x square root of 3 charge order, antiferromagnetism, and f-wave superconductivity. Around the repulsive impurities, it is found that both local charge and spin orders are induced. Furthermore, the f-wave pairing order parameter is decreased on one sublattice but increased on another honeycomb sublattice. If the charge dynamics is responsible for the superconductivity, the predicted local electronic and magnetic structure could be observed by the STM and spatial resolved NMR experiments.