Anderson Impurity in the Bulk of 3D Topological Insulators: II. The Strong Coupling Regime

TL;DR

This paper investigates the strong coupling regime of electron scattering off an Anderson impurity in 3D topological insulators, revealing unique Kondo effects with singular Fermi liquid behavior and symmetry-dependent low-temperature properties.

Contribution

It demonstrates the existence of self-screened and symmetry-dependent Kondo effects in 3D topological insulators using conformal field theory techniques.

Findings

Observation of singular Fermi liquid behavior at low temperatures

Distinct low-temperature dependencies for SO(3) and SO(4) Kondo effects

Comparison with standard SU(2) Kondo behavior

Abstract

Electron scattering off an Anderson impurity immersed in the bulk of a 3D topological insulator is studied in the strong coupling regime, where the temperature $T$ is lower than the Kondo temperature $T_K$. The system displays either a self-screened Kondo effect, or a Kondo effect with SO(3) or SO(4) dynamical symmetries. Low temperature Kondo scattering for systems with SO(3) symmetry displays the behavior of a singular Fermi liquid, an elusive property that so far has been observed only in tunneling experiments. This is demonstrated through the singular behavior as $T \to 0$ of the specific heat, magnetic susceptibility and impurity resistivity, that are calculated using well known (slightly adapted) conformal field theory techniques. Quite generally, the low temperature dependence of some of these observables displays a remarkable distinction between the SO(n=3,4) Kondo effect, compared with the standard SU(2) one.