Topological photodetection

WEYL SEMIMETAL DEVICE

Nat. Mater., 18(5), 476–481 (2019)

Nonlinear optoelectronic responses play a crucial role not only in optical devices but also in probing the fundamental properties of quantum materials. The recently discovered Weyl semimetals, belonging to the class of topological metallic phases, provide an ideal platform to explore the physical effects that relate to topology in gapless materials. The defining feature of a Weyl semimetal is the divergence of Berry curvature at the Weyl nodes, leading to topological semi-metallic phases. The divergence behaves like magnetic monopoles of the momentum space and the sign of the monopole determines the chirality. Recently, an international team of researchers led by Dong Sun, Ji Feng and Jian-Hao Chen from Peking University have made progress on high-performance photodetection based on topological properties of Weyl semimetal TaIrTe₄. They reveal that a photocurrent measurement can capture the fundamental topological feature of a Type-II Weyl cones. Furthermore, through the third-order nonlinear effect, they demonstrate that the chirality of charge carriers in this Weyl semimetal can be jointly controlled by the helicity of excitation light and an in-plane electric field, which offers new means to manipulate electron chirality. This work greatly boosts the responsivity of semimetal based photodetector at mid-infrared wavelength, and establishes the fact that photodetection is the direction that is closest to real applications for topological materials.

Zhongming Wei (Institute of Semiconductors, CAS, Beijing, China)

doi: 10.1088/1674-4926/40/6/060203