Edge photocurrent response of type-II Weyl semimetal WTe2

Photodetectors based on new materials or new structures are of great potentials to promote the performance limits of existing photo detection devices. As topological nontrivial materials, Weyl semimetals were reported to have novel optoelectronic properties and potential applications arising from their gapless linear dispersion near Weyl nodes, berry curvature divergence of Weyl nodes, internal broken of inversion or time reversal symmetry, robust fermi-arc type surface states. These unique properties lead to extraordinary optoelectronic response of Weyl semimetals. Here, using scanning photocurrent microscopy, we demonstrate that robust photocurrent will generate on edges with certain crystal direction in type-II Weyl semimetal WTe2, this photocurrent persists under a wide excitation photon energy range from near Weyl point region to high above Weyl point region. We show that the direction of photocurrent did not change with the polarization of excitation photon and a photon energy range from 0.12 eV to 1.96 eV, this edge photocurrent was determined by the symmetry of edges and may come from the nontrivial Fermi-arc type edge state of Weyl semimetal, and may result in a new type of photodetector based on it.