  Understanding the origin of superconductivity in strongly correlated electron
systems continues to be at the forefront of unsolved problems in all of
physics. Among the heavy f-electron systems, CeCoIn5 is one of the most
fascinating, as it shares many of the characteristics of correlated d-electron
high-Tc cuprate and pnictide superconductors, including the competition between
antiferromagnetism and superconductivity. While there has been evidence for
unconventional pairing in this compound, high-resolution spectroscopic
measurements of the superconducting state have been lacking. Previously, we
have used high-resolution scanning tunneling microscopy techniques to visualize
the emergence of heavy-fermion excitations in CeCoIn5 and demonstrate the
composite nature of these excitations well above Tc. Here we extend these
techniques to much lower temperatures to investigate how superconductivity
develops within a strongly correlated band of composite excitations. We find
the spectrum of heavy excitations to be strongly modified just prior to the
onset of superconductivity by a suppression of the spectral weight near the
Fermi energy, reminiscent of the pseudogap state in the cuprates. By measuring
the response of superconductivity to various perturbations, through both
quasiparticle interference and local pair-breaking experiments, we demonstrate
the nodal d-wave character of superconducting pairing in CeCoIn5.
