Multichannel Kondo Effect in an Interacting Electron System: Exact Results for the Low-Temperature Thermodynamics

TL;DR

This paper provides exact low-temperature thermodynamic results for a magnetic impurity in an interacting one-dimensional electron system, revealing interaction-insensitive magnetic susceptibility and two possible specific heat behaviors.

Contribution

It introduces exact boundary conformal field theory results for the multichannel Kondo effect with interactions, highlighting new interaction-dependent scaling behavior.

Findings

Magnetic susceptibility is unaffected by electron-electron interactions.

Impurity specific heat can either match the noninteracting case or exhibit a new critical exponent.

Interaction-dependent behavior occurs when the impurity is exactly screened (m=2S).

Abstract

We study the low-temperature thermodynamics of a spin-S magnetic impurity coupled to m degenerate bands of interacting electrons in one dimension. By exploiting boundary conformal field theory techniques, we derive exact results for the possible impurity thermal and magnetic response. The leading behavior of the impurity magnetic susceptibility is shown to be insensitive to the electron-electron interaction. In contrast, there are two types of scaling behavior of the impurity specific heat consistent with the symmetries of the problem: Either it remains the same as for the ordinary multichannel Kondo problem for noninteracting electrons, or it acquires a new leading term governed by an interaction-dependent critical exponent. We conjecture that the latter behavior is indeed realized when the impurity is exactly screened (m=2S).