Chiral pumping effect induced by rotating electric fields

TL;DR

This paper proposes an experimental setup using 3D Dirac semimetals and circularly polarized lasers to induce a chiral pumping effect, revealing a novel way to generate and control axial charge and current via the chiral anomaly.

Contribution

It introduces a new method to induce and analyze the chiral pumping effect in Dirac semimetals using high-frequency electric fields and Floquet theory, connecting to the chiral magnetic effect.

Findings

Finite charge density induced by circularly polarized laser and magnetic field

Derivation of an effective Hamiltonian using Floquet theory

Explicit calculation of pumped density and axial current

Abstract

We propose an experimental setup using 3D Dirac semimetals to access a novel phenomenon induced by the chiral anomaly. We show that the combination of a magnetic field and a circularly polarized laser induces a finite charge density with an accompanying axial current. This is because the circularly polarized laser breaks time-reversal symmetry and the Dirac point splits into two Weyl points, which results in an axial-vector field. We elucidate the appearance of the axial-vector field with the help of the Floquet theory by deriving an effective Hamiltonian for high-frequency electric fields. This anomalous charge density, i.e. the chiral pumping effect, is a phenomenon reminiscent of the chiral magnetic effect with a chiral chemical potential. We explicitly compute the pumped density and the axial-current expectation value. We also take account of coupling to the chiral magnetic effect to calculate a balanced distribution of charge and chirality in a material that behaves as a chiral battery.