Electrically and Magnetically Tunable Valley Polarization in Monolayer MoSe2 Proximitized by a 2D Ferromagnetic Semiconductor

The emergence of atomically thin valleytronic semiconductors and 2D ferromagnetic materials is opening up new technological avenues for future information storage and processing. A key fundamental challenge is to identify physical knobs that may effectively manipulate the spin-valley polarization, preferably in the device context. Here, a novel spin functional device that exhibits both electrical and magnetic tunability is fabricated, by contacting a monolayer MoSe2 with a 2D ferromagnetic semiconductor Cr2Ge2Te6. Remarkably, the valley-polarization of MoSe2 is found to be controlled by a back-gate voltage with an appreciably enlarged valley splitting rate. At fixed gate voltages, the valley-polarization exhibits magnetic-field and temperature dependence that corroborates well with the intrinsic magnetic properties of Cr2Ge2Te6, pointing to the impact of magnetic exchange interactions. Due to the interfacial arrangement, the charge-carrying trion photoemission predominates in the devices, which may be exploited to enable drift-based spin-optoelectronic devices. These results provide new insights into valley-polarization manipulation in transition metal dichalcogenides by means of ferromagnetic semiconductor proximitizing and represent an important step forward in devising field-controlled 2D magneto-optoelectronic devices.

Automated summary

By contacting a monolayer MoSe2 with a 2D ferromagnetic semiconductor, researchers have successfully manipulated the valley-polarization of MoSe2 and fabricated a spin functional device with both electrical and magnetic tunability. This study provides new insights into the manipulation of valley-polarization and represents an important step forward in the development of field-controlled 2D magneto-optoelectronic devices.