Optical conductivity of the heavy fermion superconductor CeCoIn5 -: art. no. 161101

The electrodynamic response of the heavy fermion compound CeCoIn5 is studied via infrared spectroscopy. Below 100 K the high temperature Drude-like conductivity evolves into two distinct components. At low energies a narrow mode is observed which is characteristic of the response of heavy quasiparticles. At higher energies a gap structure emerges with 2Deltasimilar to600 cm(-1) (75 meV). Examination of the fine features of the optical conductivity reveals additional absorption below the gap. This intergap resonance can be qualitatively understood as a Holstein band, where the quasiparticles are strongly coupled to a collective mode at similar to65 cm(-1) (8 meV).