Transverse Chiral Magnetic Photocurrent Induced by Linearly Polarized Light in Mirror-Symmetric Weyl Semimetals

TL;DR

This paper predicts a novel transverse photocurrent in Weyl semimetals induced by linearly polarized light and magnetic fields, which does not require broken reflection symmetry or circular polarization, with potential applications in THz radiation sensing.

Contribution

It introduces a new class of photocurrents in Weyl semimetals that occur under conditions previously thought insufficient, expanding understanding of light-matter interactions in topological materials.

Findings

The predicted photocurrent can reach microampere levels in the THz range.

The effect occurs in both type-I and type-II Weyl semimetals with broken inversion symmetry.

The phenomenon is robust even with mirror symmetry and time-reversal symmetry intact.

Abstract

A new class of photocurrents is predicted to occur in both type-I and type-II Weyl semimetals. Unlike the previously studied photocurrents in chiral materials, the proposed current requires neither circularly polarized light, nor an absence of symmetry with respect to a plane of reflection. We show that if a Weyl semimetal has a broken inversion symmetry then linearly polarized light can induce a photocurrent transverse to the direction of an applied magnetic field, in spite of the symmetry with respect to a reflection plane and the time reversal symmetry. The class of materials in which we expect this to occur is sufficiently broad and includes the transition metal monopnictides such as TaAs. The effect stems from the dynamics of Weyl chiral quasi-particles in a magnetic field, restricted by the symmetries described above; because the resulting current is transverse to the direction of magnetic field, we call it the transverse chiral magnetic photocurrent. The magnitude of the resulting photocurrent is predicted to be significant in the THz frequency range, about $0.75\; \mathrm{\mu A}$ for type-I and $2.5\; \mathrm{\mu A}$ for type-II Weyl semimetals. This opens the possibility to utilize the predicted transverse chiral magnetic photocurrent for sensing unpolarized THz radiation.