Non-Fermi-Liquid Properties and Exotic Superconductivity in CeCu2Si2 and (UTh)Be13

Tetragonal CeCu2Si2 [1] and cubic UBe13 [2] belong to the class of strongly correlated (electron materials where a periodic lattice of partially filled f shells is embedded in a metallic environment. Below a characteristic “Kondo temperature” Tk, typically of the order of 10K, quasiparticles composed of both local f degrees of freedom and itinerant conduction-electron degrees of freedom form. As has been inferred from the giant Sommerfeld coefficient r of about 1 J/K2mole, the huge effective quasiparticle masses m· (100–1000 mel) are governed by the f degrees of freedom. The discontinuity of the specific heat at Tc which was found to scale with the large γ [1, 2] proved that superconductivity is, indeed, formed by those heavy fermions (HF).