Emergent Electromagnetic Induction and Adiabatic Charge Pumping in Weyl Semimetals

TL;DR

This paper investigates how circularly polarized light induces a photovoltaic current in Weyl semimetals through emergent electromagnetic induction, revealing a novel mechanism distinct from traditional effects.

Contribution

It demonstrates that circularly polarized light causes a photovoltaic current in Weyl semimetals via emergent electromagnetic induction linked to Weyl nodes acting as magnetic monopoles.

Findings

Photocurrent is induced by circularly polarized light.

Emergent electromagnetic induction explains the photocurrent.

Potential for experimental identification of Weyl semimetals.

Abstract

The photovoltaic effect in a Weyl semimetal due to the adiabatic quantum phase is studied. We particularly focus on the case in which an external ac electric field is applied to the semimetal. In this setup, we show that a photocurrent is induced by the ac electric field. By considering a generalized Weyl Hamiltonian with nonlinear terms, it is shown that the photocurrent is induced by circularly, rather than linearly, polarized light. This photovoltaic current can be understood as an emergent electromagnetic induction in the momentum space; the Weyl node is a magnetic monopole in the momentum space, of which the electric field is induced by the circular motion. This result is distinct from conventional photovoltaic effects, and potentially useful for experimentally identifying Weyl semimetals in chiral crystals.