Magnetic Order Induced Suppression of Photoluminescence in van der Waals Magnet CrPS4

The intriguing physical phenomena and significant application potential are driving the development of two-dimensional (2D) magnetic materials. The coupling of 2D magnetic order with electrons, phonons, and photons can profoundly influence the physical properties of 2D magnets, leading to advancements in spintronics and optoelectronics. However, the practical application of 2D magnets is impeded by the air-instability and inadequate understanding of the complex coupling effects associated with 2D magnetic ordering. A study is presented here on the temperature, wavelength, and field-dependent photoluminescence (PL) spectra of one of the few air-stable van der Waals magnet CrPS4. A notable decreasing of the dominant PL peak intensity is observed in the presence of magnetic order and external magnetic field. Combined with theoretical calculations, this study determines that the modulation of PL intensity by magnetic order stems from the spin-restricted selection rule imposing on the electron-hole radiative combination, resulting in the darkening of the bright excitons. Since spin-polarized electronic band structure is prevalent in 2D magnets, these findings unveil a universal spin-charge coupling effect and offer valuable insights into the fascinating interplay between magnetism and optical properties in 2D magnets, advocating strong promises for the development of advanced magneto-optoelectronic devices based on CrPS4.