Optimal charge inhomogeneity for the d plus id-wave superconductivity in the intercalated graphite CaC6

The coexistence of superconductivity and charge inhomogeneity was observed in many cuprate superconductors. The relationship between those two is still controversial. Similarly, in the graphene sheets of the intercalated graphitic superconductor CaC6, the charge inhomogeneity was also observed. We simulate such a system by constructing the Hubbard model on the honeycomb lattice with charge inhomogeneity imposed by force. Utilizing the finite-temperature determinant quantum Monte Carlo algorithm, we examine the relationship between the superconducting pairing and the charge inhomogeneity. An optimal charge inhomogeneity for the d+id-wave pairing is found. While for other artificial charge inhomogeneities, the d+id-wave pairing is monotonically suppressed. The possible pi-phase shift induced by charge inhomogeneity is also examined.

Automated summary

The coexistence of superconductivity and charge inhomogeneity is observed in cuprate superconductors and the intercalated graphitic superconductor CaC6. This study simulates this system and examines the relationship between superconducting pairing and charge inhomogeneity. The findings suggest an optimal charge inhomogeneity for d+id-wave pairing and show a monotonic suppression of the pairing for other artificial charge inhomogeneities. The possible pi-phase shift induced by charge inhomogeneity is also explored.