We study theoretically the single impurity effect on graphene-based superconductors. Four different pairing symmetries are discussed. Sharp in-gap resonant peaks are found near the impurity site for the d + id pairing symmetry and the p + ip pairing symmetry when the chemical potential is large. As the chemical potential decreases, the in-gap states are robust for the d + id pairing symmetry while they disappear for the p + ip pairing symmetry. Such in-gap peaks are absent for the fully gapped extended s-wave pairing symmetry and the nodal f-wave pairing symmetry. The existence of the ingap resonant peaks can be explained well based on the sign-reversal of the superconducting gap along different Fermi pockets and by analyzing the denominator of the T-matrix. All of the features may be checked by the experiments, providing a useful probe for the pairing symmetry of graphene-based superconductors.

我们从理论上研究了对石墨烯基超导体的单一杂质效应。讨论了四种不同的配对对称性。当化学势较大时，在d + i d配对对称性和p + i p配对对称性的杂质位点附近发现了尖锐的间隙内共振峰。随着化学势的降低，间隙内态对于d + i d配对对称性很强，而对于p + i p配对对称性则消失。对于完全有间隙的扩展s波对对称性和节点f都没有这样的间隙峰波对对称。基于沿着不同费米腔的超导间隙的正负号反转，以及通过分析T矩阵的分母，可以很好地解释单峰共振峰的存在。所有特征均可通过实验检查，为基于石墨烯的超导体的配对对称性提供了有用的探针。