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

We have measured the current-voltage characteristics of point contacts between UBe13 or UPt3 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 (dVdI vs V) there appear zero-bias minima of width 2 below Tc. The ratio 2 kBTc is close to the BCS value. The tunneling spectra of UPt3 exhibit weak additional structure below Tc. A value 2 has been estimated, which is a factor of 2 larger than that for the metal point contacts. © 1987 The American Physical Society