Quantum impurity on the surface of a topological insulator

TL;DR

This paper demonstrates that a quantum magnetic impurity on a topological insulator's surface can be modeled using a pseudo-gap Anderson impurity framework, revealing full screening at low temperatures away from the Dirac point.

Contribution

It introduces a mapping of the impurity Hamiltonian to a pseudo-gap Anderson model with complex hybridization structures on topological insulator surfaces.

Findings

Impurity is fully screened when Fermi level is away from Dirac point.

Hybridization involves complex reciprocal and spin space structures.

Mapping provides new insights into impurity behavior on topological insulators.

Abstract

It is shown that the Hamiltonian for a quantum magnetic impurity on the surface of a topological insulator can be mapped to the conventional pseudo-gap Anderson impurity model, albeit with the combinations of continuum states which hybridize with the impurity having more complex structure in the reciprocal and spin space. If the Fermi level is away from the Dirac point, the impurity is predicted to be fully screened at low enough temperatures, i.e., there are no residual degrees of freedom.