POINT-CONTACT STUDY OF THE HEAVY-FERMION SYSTEM URU2SI2

We have performed a series of point-contact experiments, i.e. measurements of the voltage-dependent differential resistance, on single crystals of the heavy-fermion metal URu2Si2, which is both antiferromagnetic and superconducting, in the temperature range between 0.8 and 20 K. Our most important results are strong anomalies due to the antiferromagnetism below T(N) = 17 K. These anomalies appear to be composed of parts fitting into a self-heating model and other, possibly spectroscopic parts. A unique, i.e. either thermal or ballistic model thus seems to be inadequate for the description of these point-contacts. In the characteristics of high-ohmic contacts we find zero-bias maxima of a width comparable to the width of a charge- or spin-density wave gap found in specific heat measurements. For the superconducting state below T(c) = 1.3 K, our measurements indicate a zone of strongly suppressed superconductivity near the surface.