Giant Circular Dichroism in Proximitized WS₂ Spin-Valley Transistors for Complementary Optoelectronics and Reconfigurable Logics.

Abstract

The coupling of valley and spin degrees of freedom in 2D materials holds significant promise for advancing novel device applications. In this study, a highly polarized spin-valley transistor based on the circular dichroic photocurrent in WS₂ is demonstrated. By integrating highly spin-selective tunneling spin detectors and leveraging the magnetic proximity effect of spin-polarized substrates, the spin degeneracy in optical transition and spin transport can be broken. A giant photocurrent polarization of 41.90% is realized at room temperature under ultraviolet light irradiation. Interestingly, the sign of the circular dichroism can be reversed by switching the magnetization of substrates and electrodes, showing an opposite resistance state under circularly polarized light. This device has removed the hurdle for developing complementary phototransistors (as they are always in low-resistance states under light illumination), which are further exploited to construct reconfigurable logic gates. The findings will pave the way for new developments in optical couplers and on-chip optical computing technologies.