On the preparation and the superconducting properties of CeRu 2 and its mixed crystals with ARu 2 (A = rare-earth element) and CeB 2 (B = Mn, Fe-group or Pt-group element)

Abstract

We report on the preparation and the superconducting properties of CeRu 2 and its mixed crystals Ce 1− x A x Ru 2 and Ce( Ru 1− x B x ) 2 (A = rare-earth element, B = Mn, Fe-group or Pt-group element). Homogeneous samples of the compound and its solid solutions have been prepared by a special heat treatment, and the initial susceptibility was measured as a function of temperature. For small concentrations of rare-earth elements T c is slightly increased as compared with pure CeRu 2( T c = 6.2 K), for larger concentrations T c decreases approximately with the fourth power of the concentration. Superconductivity and magnetism meet for alloys with ≈ 13 mole.% GdRu 2, 18 mole. % TbRu 2, 21 mole. % DyRu 2, and 27 mole. % HoRu 2. For Ce( Ru 1− x B x ) 2 T c decreases linearly with x, d T c/d x being especially large for Mn and Fe. Since the available cerium showed a Fe-content of several thousand ppm, the metal was zonerefined before use. From the different behaviour of the A- and B-solutions we conclude that superconductivity may be connected with the Ru-sublattice.