Anisotropic Superconductivity in the Kondo Lattice

Abstract

Various types of anisotropic superconductivity have been investigated near its transition temperature in the periodic Anderson Hamiltonian with a weak attractive interaction between the nearest neighbor f electrons. The superconductivity with the s-, p- or dγ-symmetry is possible in a model where the f sites form a simple cubic lattice. Due to the finite range of the interaction, even the s-symmetry Cooper pairs can be anisotropic. This anisotropic s-wave superconductivity has many different properties from the ordinary BCS superconductivity if the Fermi wave vector is large; the transition temperature T_c can be significantly reduced by nonmagnetic impurities, the specific heat jump can be smaller than the BCS value, and the energy gap near T_c can vanish along lines on the Fermi surface. The competition among different symmetries is discussed.