Magnetism and superconductivity in heavy fermion superconductor CeCo(In0.97Cd0.03)5

Zero field (ZF) and transverse field (TF) muon spin relaxation and rotation (μSR) experiments have been carried out in the Cd-doped heavy fermion superconductor CeCoIn5 to investigate its superconducting state. The ZF-μSR results in CeCo(In0.97Cd0.03)5 revealed that no spontaneous magnetic field was induced below its superconducting transition temperature (Tc), indicating no evidence for time reversal symmetry breaking. The muon Knight shifts obtained from TF-μSR measurements decrease significantly below Tc, consistent with a spin-singlet state as in the parent compound CeCoIn5, which is a d-wave superconductor.