Spin-Enhanced Self-Powered Light Helicity Detecting Based on Vertical WSe-CrI Heterojunction.

Two-dimensional (2D) magnetic semiconductors offer an intriguing platform for investigating magneto-optoelectronic properties and hold immense potential in developing prospective devices when they are combined with valley electronic materials like 2D transition-metal dichalcogenides. Herein, we report various magneto-optoelectronic response features of the vertical hBN-FLG-CrI-WSe-FLG-hBN van der Waals heterostructure. Through a sensible layout and exquisite manipulation, an hBN-FLG-CrI-FLG-hBN heterostructure was also fabricated on identical CrI and FLGs for better comparison. Our results show that the WSe-CrI heterostructure, acting as a - heterojunction, has advantageous capability in light detection, especially in self-powered light helicity detecting. In the WSe-CrI heterojunction, the absolute value of photocurrent exhibits obvious asymmetry with respect to the bias , with the of reversely biased WSe-CrI heterojunction being larger. When the CrI is fully spin-polarized under a 3 T magnetic field, the reversely biased WSe-CrI heterojunction exhibits advantageous capability in light helicity detecting. Both the short-circuit currents and show one-cycle fluctuation behaviors when the quarter-wave plate rotates 180°, and the corresponding photoresponsivity helicities can be as high as 18.0% and 20.1%, respectively. We attribute the spin-enhanced photovoltaic effect in the WSe-CrI heterojunction and its contribution to circularly polarized light detection to the coordination function of the spin-filter CrI, the valley electronic monolayer WSe, and the spin-dependent charge transfer between them. Our work helps us understand the interplay between the magnetic and optoelectronic properties of WSe-CrI heterojunctions and promotes the developing progress of prospective 2D spin optoelectronic devices.