Nonmagnetic impurity resonance states as a test of superconducting pairing symmetry in CeCoIn5

We theoretically study the effect of a nonmagnetic impurity in heavy fermion superconductor CeCoIn5 within a coherent three-dimensional Anderson lattice model and the T-matrix approximation approach. By considering two known possible pairing symmetry candidates d(x2-y2) and d(xy), we find that although both total density of states exhibit a similar V-shaped gaplike feature, only d(x2-y2)-wave pairing symmetry gives rise to robust intragap impurity resonance states reflected by the resonance peaks near the Fermi energy in the local density of states. These features can be readily probed by scanning tunneling microscopy experiments, and are proposed to shed light on the pairing symmetry and provide hints on the microscopic mechanism of unconventional superconductivity in the Ce-based heavy fermion superconductors.