Edge photogalvanic effect caused by optical alignment of carrier momenta in 2D Dirac materials

TL;DR

This paper demonstrates that optical excitation in 2D Dirac materials induces an edge photocurrent due to electron-hole momentum alignment, which can be enhanced using ratchet-like structures and is influenced by magnetic fields.

Contribution

It provides a microscopic theory of the edge photogalvanic effect in 2D Dirac materials, including the influence of magnetic fields and structural enhancements.

Findings

Photocurrent arises from electron-hole momentum alignment and depends on radiation polarization.

Magnetic fields introduce additional imbalance, affecting the photocurrent.

Ratchet-like structures can significantly amplify the photocurrent.

Abstract

We show that the inter-band absorption of radiation in a 2D Dirac material leads to a direct electric current flowing at sample edges. The photocurrent originates from the momentum alignment of electrons and holes and is controlled by the radiation polarization. We develop a microscopic theory of such an edge photogalvanic effect and calculate the photocurrent for gapped and gapless 2D Dirac materials, also in the presence of a static magnetic field which introduces additional imbalance between the electron and hole currents. Further, we show that the photocurrent can be considerably multiplied in a ratchet-like structure with an array of narrow strips.