Spin-transition modulated light-emitting devices in a 2D magnet.

Emerging two-dimensional magnetic semiconductors represent transformative platforms to explore magneto-optics and opto-spintronic applications. Though two-dimensional opto-spintronics has attracted tremendous research efforts in spin-dependent photodetectors and non-volatile memory components, the realization of one core application - spin-modulated light-emitting device - remains elusive so far. Here, we successfully realize prototype spin-modulated light-emitting device integrated with a two-dimensional semiconducting magnet chromium sulfide bromide, demonstrating considerable electroluminescence down to bilayers. Intriguingly, it's discovered to be directly manipulated by spin-flip and spin-canting transitions. Notably, the intrinsic carrier-tunable interlayer magnetic coupling in chromium sulfide bromide enables electroluminescence to actively amplify magnetic hysteresis (via spin-flip) and continuously tune magnetic order (via spin-canting) with robust anisotropy, establishing a connection between carrier injection, magnetic phase transitions, and optical emission. The prototype demonstration of spin-modulated light-emitting device establishes an indispensable scheme of opto-spintronic devices leveraging two-dimensional spin transitions and strong excitonic effects, presenting a critical step towards integrated two-dimensional opto-spintronics.