Tandem Pairing in Heavy Fermion Superconductors

TL;DR

This paper investigates the internal structure of heavy fermion superconductors, revealing a tandem pairing mechanism involving d-wave quasiparticles and composite pairs, which enhances the transition temperature and predicts measurable electrostatic effects.

Contribution

It introduces a novel tandem pairing model combining antiferromagnetic and Kondo interactions within a single unit cell, advancing understanding of heavy fermion superconductivity.

Findings

Tandem pairing involves d-wave quasiparticles and composite pairs.

The model predicts a superconducting shift in NQR frequency due to quadrupole moments.

Enhanced transition temperature results from cooperative interactions.

Abstract

We examine the internal structure of the heavy fermion condensate, showing that it necessarily involves a d-wave pair of quasiparticles on neighboring lattice sites, condensed in tandem with a composite pair of electrons bound to a local moment, within a single unit cell. These two components draw upon the antiferromagnetic and Kondo interactions to cooperatively enhance the superconducting transition temperature. The tandem condensate is electrostatically active, with a small electric quadrupole moment coupling to strain that is predicted to lead to a superconducting shift in the NQR frequency.