Understanding bulk photovoltaic effect in type-II Weyl semimetal Td-WTe2 using polarization dependent photocurrent measurement

Topological effects in a Weyl semimetal are explored in developing self-powered photodetectors at room temperature. The observed photocurrent is attributed to a combined effect of photothermoelectric effect and bulk photovoltaic phenomenon and is found to be a non-linear optical effect that converts light into electrical current. The self-powered photoresponse at 640 nm excitation wavelength reveals the presence of a diverging Berry curvature of tungsten ditelluride (Td-WTe2) at room temperature. The different perspective of polarization dependent photocurrent spectroscopy is used to separate the photothermal current from the shift current and the circular photo galvanic response from the linear photo galvanic response.