Electrical switching of spin-polarized light-emitting diodes based on a 2D CrI 3 /hBN/WSe 2 heterostructure.

Spin-polarized light-emitting diodes (spin-LEDs) convert the electronic spin information to photon circular polarization, offering potential applications including spin amplification, optical communications, and advanced imaging. The conventional control of the emitted light's circular polarization requires a change in the external magnetic field, limiting the operation conditions of spin-LEDs. Here, we demonstrate an atomically thin spin-LED device based on a heterostructure of a monolayer WSe 2 and a few-layer antiferromagnetic CrI 3 , separated by a thin hBN tunneling barrier. The CrI 3 and hBN layers polarize the spin of the injected carriers into the WSe 2 . With the valley optical selection rule in the monolayer WSe 2 , the electroluminescence exhibits a high degree of circular polarization that follows the CrI 3 magnetic states. Importantly, we show an efficient electrical tuning, including a sign reversal, of the electroluminescent circular polarization by applying an electrostatic field due to the electrical tunability of the few-layer CrI 3 magnetization. Our results establish a platform to achieve on-demand operation of nanoscale spin-LED and electrical control of helicity for device applications.