Emergence of Weyl metals driven by doped magnetic impurities in spin-orbit coupled semiconductors

TL;DR

This paper demonstrates how doping magnetic impurities in spin-orbit coupled semiconductors can induce Weyl metal phases through quantum fluctuations, even without ferromagnetic order or strong magnetic fields, revealing a novel non-Fermi liquid topological phase.

Contribution

It introduces a theoretical framework showing magnetic impurity doping can drive Weyl metal emergence via renormalization group analysis, highlighting the role of quantum fluctuations and disorder effects.

Findings

Magnetic impurity doping can induce Weyl metals without ferromagnetic order.

External magnetic fields can be overcome by impurity effects to realize Weyl phases.

The emergent Weyl metal phase exhibits non-Fermi liquid behavior with strong magnetic fluctuations.

Abstract

Constructing an effective field theory in terms of doped magnetic impurities (described by an O(3) vector model with a random mass term), itinerant electrons of spin-orbit coupled semiconductors (given by a Dirac theory with a relatively large mass term), and effective interactions between doped magnetic ions and itinerant electrons (assumed by an effective Zeeman coupling term), we perform the perturbative renormalization group analysis in the one-loop level based on the dimensional regularization technique. As a result, we find that the mass renormalization in dynamics of itinerant electrons acquires negative feedback effects due to quantum fluctuations involved with the Zeeman coupling term, in contrast with that of the conventional problem of quantum electrodynamics, where such interaction effects enhance the fermion mass more rapidly. Recalling that the applied magnetic field decreases the band gap in the presence of spin-orbit coupling, this renormalization group analysis shows that the external magnetic field overcomes the renormalized band gap, allowed by doped magnetic impurities even without ferromagnetic ordering. In other words, the Weyl metal physics can be controlled by doping magnetic impurities into spin-orbit coupled semiconductors, even if the external magnetic field alone cannot realize the Weyl metal phase due to relatively large band gaps of semiconductors. Furthermore, we emphasize that quasiparticles do not exist in this emergent disordered Weyl metal phase due to correlations with strong magnetic fluctuations. This non-Fermi liquid type Weyl metal state may be regarded to be a novel metallic phase in the respect that a topologically nontrivial band structure appears in the vicinity of quantum criticality.