The Kondo screening cloud: what can we learn from perturbation theory?

TL;DR

This paper investigates the Kondo screening cloud using renormalization group improved perturbation theory, deriving scaling functions for local spin susceptibility and clarifying the spatial extent and behavior of the screening cloud.

Contribution

It provides a detailed analysis of the Kondo screening cloud's spatial properties and clarifies the behavior of the local spin susceptibility at various distances using perturbation theory.

Findings

Non-oscillating part of susceptibility is short-range

Screening cloud does not show weak coupling behavior inside

Scaling functions for susceptibility are derived

Abstract

We analyse the role which the distance scale $\xi_K = v_F/T_K$ plays in the single-impurity Kondo problem using renormalization group improved perturbation theory. We derive the scaling functions for the local spin susceptibility in various limiting cases. In particular, we demonstrate exactly that the non-oscillating part of it should be short-range, i.e., vanish for distances $r \gg 1/k_F$ and show explicitly that the interior of the screening cloud {\it does not} exhibit weak coupling behavior.