Robust edge photocurrent response on layered Type II Weyl semimetal WTe2

TL;DR

This paper reports a robust edge photocurrent response in layered Type II Weyl semimetal WTe2, driven by crystalline symmetry breaking and topological surface states, promising for broad-spectrum photodetection and energy harvesting.

Contribution

It demonstrates a universal, robust edge photocurrent in WTe2 due to symmetry breaking and topological states, expanding understanding of quantum material-based photodetectors.

Findings

Edge photocurrent is robust over a wide photon energy range.

The response is linked to crystalline symmetry breaking and topological surface states.

This mechanism is likely universal in similar quantum materials.

Abstract

Photo sensing and energy harvesting based on exotic properties of quantum materials and new operation principles have great potentials to break the fundamental performance limit of conventional photodetectors and solar cells. As topological nontrivial materials, Weyl semimetals have demonstrated novel optoelectronic properties that promise potential applications in photo detection and energy harvesting arising from their gapless linear dispersion near Weyl nodes and Berry field enhanced nonlinear optical effect at the vicinity of Weyl nodes. In this work, we demonstrate robust photocurrent generation from charge separation of photoexctied electron-hole pairs at the edge of Td-WTe2, a type-II Weyl semimetal, due to crystalline-symmetry breaking along certain crystal fracture directions and possibly enhanced by robust fermi-arc type surface states. Using scanning photocurrent microscopy (SPCM) measurements, we further demonstrate that the edge current response is robust over a wide excitation photon energy. We find that this robust feature is highly generic, and shall arise universally in a wide class of quantum materials with similar crystal symmetries. In addition, possible connections between these edge photocurrents and topological properties of Weyl semimetals are explored. The robust and generic edge current response demonstrated in this work provides a new type of charge separation mechanism for photosensing and energy harvesting over broad wavelength range.