Emergent gravity and chiral anomaly in Dirac semimetals in the presence of dislocations

TL;DR

This paper explores how dislocations in Dirac semimetals induce emergent gravitational and electromagnetic fields, leading to observable quantum anomalies and chiral magnetic effects along dislocations.

Contribution

It introduces a theoretical framework for understanding emergent gauge and gravitational fields in Dirac semimetals with dislocations, revealing novel quantum anomaly phenomena.

Findings

Dislocations generate singular torsion and emergent magnetic flux.

Quantum anomalies cause quasiparticle current pumping along dislocations.

Chiral magnetic effect manifests as electric current along dislocations.

Abstract

We consider the recently discovered Dirac semimetals with two Dirac points $\pm{\bf K}$. In the presence of elastic deformations each fermion propagates in a curved space, whose metric is defined by the expansion of the effective Hamiltonian near the Dirac point. Besides, there is the emergent electromagnetic field that is defined by the shift of the Dirac point. We consider the case, when the deformations are caused by the dislocations. The dislocation carries singular torsion and the quantized flux of emergent magnetic field. Both torsion singularity and emergent magnetic flux may be observed in the scattering of quasiparticles on the dislocation due to Stodolsky and Aharonov - Bohm effects. We discuss quantum anomalies in the quasiparticle currents in the presence of emergent gauge and gravitational fields and the external electromagnetic field. In particular, it is demonstrated, that in the presence of external electric field the quasiparticles/holes are pumped from vacuum along the dislocation. The appeared chiral imbalance along the dislocation drives the analogue of chiral magnetic effect, that is the appearance of electric current along the dislocation.