  Since the progress in the fabrication techniques of thin-films of exotic
materials such as strongly correlated heavy-fermion compounds, microscopic
studies of the magnetic and electronic properties inside the films have been
needed. Herein, we report the first observation of 115In nuclear quadrupole
resonance (NQR) in an epitaxial film of the heavy-fermion superconductor
CeCoIn5, for which the microscopic field gradient within the unit cell as well
as magnetic and superconducting properties at zero field are evaluated. We find
that the nuclear spin-lattice relaxation rate in the film is in excellent
agreement with that of bulk crystals, whereas the NQR spectra show noticeable
shifts and significant broadening indicating a change in the electric-field
distribution inside the film. The analysis implies a displacement of In layers
in the film, which however does not affect the magnetic fluctuations and
superconducting pairing. This implies that inhomogeneity of the electronic
field gradient in the film sample causes no pair breaking effect.
