POINT-CONTACT STUDIES OF THE SUPERCONDUCTING GAP OF CERU2

The measured dV/dI(V) curves of point contacts between the intermetall ic compound CeRu2 in the superconducting state and the normal metal Cu correspond fairly well to the Blonder-Tinkham-Klapwijk model. It is u sed to obtain temperature and magnetic field dependence of the superco nducting gap Delta. The Delta(T) dependence corresponds well to the BC S theory with 2 Delta(0)/k(B)T(c)=3.1 +/- 0.1. Additionally, a region of gapless superconductivity between T-csimilar or equal to 4.4 5.4 K and T(c)(bulk)similar or equal to 6.2 K is found. The gap decreases approximately linearly in a magnetic field and vanishes in a fieId B-c similar or equal to 3.5 T, which is well below the upper critical fie ld B(c2)similar or equal to 6T and close to the irreversibility field. (C) 1998 American Institute of Physics.