Point-contact spectra of the heavy-fermion superconductors UBe13 and UPt3.

We have measured the current-voltage characteristics of point contacts between UBe/sub 13/ or UPt/sub 3/ and the normal metals W or Pt (metallic point contacts) or GaAs (Schottky-barrier tunneling contact) in the temperature range between 50 mK and 1 K. In the metal-point-contact characteristics (dV/dI vs V) there appear zero-bias minima of width 2..delta.. below T/sub c/. The ratio 2..delta../k/sub B/T/sub c/ is close to the BCS value. The tunneling spectra of UPt/sub 3/ exhibit weak additional structure below T/sub c/. A value 2..delta.. has been estimated, which is a factor of 2 larger than that for the metal point contacts.