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

Abstract

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 π-phase shift induced by charge inhomogeneity is also examined.

Graphical abstract

Keywords

intercalated graphitic superconductor / charge inhomogeneity / Hubbard model / d+id-wave pairing

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Acknowledgements

We would like to thank R. Mondaini for stimulating discussions. This work was sponsored by the Natural Science Foundation of Chongqing, China (Grant No. cstc2021jcyj-msxmX1009) and the Joint Guiding Project of Natural Science Foundation of Heilongjiang Province (Grant No. LH2019A011).

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