Co-operative Two-Channel Kondo Effect

TL;DR

This paper explores how additional screening channels in a Kondo lattice destabilize the Fermi liquid, leading to a new phase with long-range composite order due to divergent fluctuations.

Contribution

It reveals that extra screening channels act as relevant perturbations, inducing a transition to a state with long-range composite order, contrary to previous beliefs.

Findings

Additional screening channels destabilize the Fermi liquid.

Zero modes facilitate divergent composite pair susceptibility.

System exhibits instability into a long-range ordered state.

Abstract

We discuss how the properties of a single-channel Kondo lattice model are modified by additional screening channels. Contrary to current wisdom, additional screening channels appear to constitute a relevant perturbation which destabilizes the Fermi liquid. When a heavy Fermi surface develops, it generates zero modes for Kondo singlets to fluctuate between screening channels of different symmetry, producing a divergent composite pair susceptibility. Additional screening channels couple to these divergent fluctuations, promoting an instability into a state with long-range composite order.