Co-operative Kondo Effect in the two-channel Kondo Lattice

TL;DR

This paper proposes that in a two-channel Kondo lattice, channel interference leads to a cooperative effect resulting in a superconducting state of composite pairs, driven by the non-conservation of channel quantum number.

Contribution

It introduces a novel mechanism for superconductivity in heavy fermion systems via channel interference and composite pairing, supported by a detailed mean-field theory.

Findings

Constructive interference of Kondo channels induces superconductivity.

Divergent composite pair susceptibility signals instability towards composite order.

Heavy Fermi surface fluctuations facilitate the formation of composite pairs.

Abstract

We discuss the possibility of a co-operative Kondo effect driven by channel interference in a Kondo lattice where local moments are coupled to a single Fermi sea via two orthogonal scattering channels. In this situation, the channel quantum number is not conserved. We argue that the absence of channel conservation causes the Kondo effect in the two channels to constructively interfere, giving rise to a superconducting condensate of composite pairs, formed between the local moments and the conduction electrons. Our arguments are based on the observation that a heavy Fermi surface gives rise to zero modes for Kondo singlets to fluctuate between screening channels of different symmetry, producing a divergent composite pair susceptibility. Secondary screening channels couple to these divergent fluctuations, promoting an instability into a state with long-range composite order. We present detailed a detailed mean-field theory for this superconducting phase, and discuss the possible implications for heavy fermion physics.