Eur. Phys. J. B 28, 9-28 (2002)
https://doi.org/10.1140/epjb/e2002-00195-8

Composite spin-triplet superconductivity in an SU(2)⊗SU(2) symmetric lattice model

Institut für Festkörperphysik, Technical University Darmstadt, 64289 Darmstadt, Germany

Corresponding author: ^a frithjof@fkp.tu-darmstadt.de

Received: 28 February 2002
Revised: 18 April 2002
Published online: 9 July 2002

Abstract

The two-channel Anderson lattice model which has SU(2)⊗SU(2) symmetry is of relevance to understanding of the magnetic, quadrupolar and superconducting phases in U_1-xTh_xBe₁₃ or Pr based skutterudite compounds such as PrFe₄P₁₂ or PrOs₄Sb₁₂. Possible unconventional superconducting phases of the model are explored. They are characterized by a composite order parameter comprising of a local magnetic or quadrupolar moment and a triplet conduction electron Cooper-pair. This binding of local degrees of freedom removes the entropy of the non Fermi-liquid normal state. We find superconducting transitions in the intermediate valence regime which are suppressed in the stable moment regime. The gap function is non analytic and odd in frequency: a pseudo-gap develops in the conduction electron density of states which vanishes as close to . In the strong intermediate valent regime, the gap function acquires an additional -dependence.