Very-low-temperature tunneling spectroscopy in the heavy-fermion superconductor ${\mathrm{PrOs}}_4{\mathrm{Sb}}_{12}$

We present scanning tunneling spectroscopy measurements on the heavy-fermion superconductor ${\mathrm{PrOs}}_4{\mathrm{Sb}}_{12}.$ Our results show that the superconducting gap opens over a large part of the Fermi surface. The deviations from isotropic BCS s-wave behavior are discussed in terms of a finite distribution of values of the superconducting gap.