Kondo effect in three-dimensional Dirac and Weyl systems

TL;DR

This paper explores how magnetic impurities exhibit diverse Kondo effects in three-dimensional Dirac and Weyl materials, highlighting the influence of electronic structure and symmetry on the emergence of Kondo phenomena.

Contribution

It reveals the conditions under which Kondo physics appears or is suppressed in Dirac and Weyl systems, including the effects of symmetry breaking and chemical potential deviations.

Findings

Dirac semimetals at the Dirac point are unlikely to show Kondo effect due to pseudogap.

Proximity to a quantum critical point alters Kondo behavior with small chemical potential shifts.

Time-reversal symmetry influences Kondo variants in Weyl systems.

Abstract

Magnetic impurities in three-dimensional Dirac and Weyl systems are shown to exhibit a fascinatingly diverse range of Kondo physics, with distinctive experimental spectroscopic signatures. When the Fermi level is precisely at the Dirac point, Dirac semimetals are in fact unlikely candidates for a Kondo effect due to the pseudogapped density of states. However, the influence of a nearby quantum critical point leads to the unconventional evolution of Kondo physics for even tiny deviations in the chemical potential. Separating the degenerate Dirac nodes produces a Weyl phase: time-reversal symmetry-breaking precludes Kondo due to an effective impurity magnetic field, but different Kondo variants are accessible in time-reversal invariant Weyl systems.