Topological photocurrent responses from chiral surface Fermi arcs

TL;DR

This paper introduces a novel surface-only topological photocurrent response from chiral Fermi arcs in topological semimetals, demonstrating its robustness and potential for material design.

Contribution

It proposes and quantitatively analyzes a new surface photocurrent response from Fermi arcs, distinct from bulk effects, and generalizes the findings to all cubic chiral space groups.

Findings

Fermi arc photocurrents can be perpendicular to bulk injection currents.

The response is robust and determined by crystal symmetry.

Predicted new material candidates exhibiting this effect.

Abstract

The nonlinear optical responses from topological semimetals are crucial in both understanding the fundamental properties of quantum materials and designing next-generation light-sensors or solar-cells. However, previous work was focusing on the optical effects from bulk states only, disregarding topological surface responses. Here we propose a new (hitherto unknown) surface-only topological photocurrent response from chiral Fermi arcs. Using the ideal topological chiral semimetal RhSi as a representative, we quantitatively compute the topologically robust photocurrents from Fermi arcs on different surfaces. By rigorous crystal symmetry analysis, we demonstrate that Fermi arc photocurrents can be perpendicular to the bulk injection currents regardless of the choice of materials' surface. We then generalize this finding to all cubic chiral space groups and predict material candidates. Our theory reveals a powerful notion where common crystalline-symmetry can be used to induce universal topological responses as well as making it possible to completely disentangle bulk and surface topological responses in many conducting material families.