Layer-dependent structural stability and electronic properties of CrPS₄ under high pressure

Interlayer coupling plays an important role in determining the lattice vibrations and optical properties of two-dimensional (2D) materials. By applying pressure, the interlayer coupling in 2D materials can be effectively modified, thereby tuning their physical properties. In this study, we systematically investigated the crystal structure and electronic structure of bulk and ultrathin CrPS₄ by combining in situ high-pressure Raman and photoluminescence (PL) spectroscopy measurements. The results of high-pressure Raman spectroscopy indicate that, with an increase in layer number, the pressure at which the A₂ and B₃ Raman peaks merge into a single peak increases, meanwhile, a delay in fluorescence quenching is observed. These can be attributed to the much harder structural distortion or even phase transitions, and the electronic phase transition of CrPS₄ with stronger interlayer coupling in thicker layer. The current structural and optical investigation under pressure will provide a firm basis for future studies and applications of atomically thin magnetic semiconductors, which hold potential for the development of strain-sensitive and optical-sensing devices.