Self-Intercalated CrxSy: 2D Ferrimagnetic Materials From Low-Temperature to Room-Temperature.

The advancement of spintronics relies on the development of 2D magnetic materials with robust room-temperature properties. However, challenges such as low Curie temperatures (TC) and ambient instability have hindered their practical applications. In this study, we employ chemical vapor deposition (CVD) combined with salt-assisted methods and optimize growth parameters to synthesize phase-tunable CrxSy compounds, including rhombohedral Cr2S3 (ferrimagnetic below 120 K), trigonal Cr5S6 (room-temperature ferrimagnetic), and hexagonal CrS (antiferromagnetic). Our findings reveal that self-intercalation of Cr atoms significantly modifies the lattice structure, electronic states, and magnetic properties of these materials. Cr5S6 exhibits half-metallic characteristics with room-temperature ferrimagnetism, representing a significant advancement for practical 2D magnetic materials. The charge transfer from self-intercalated Cr atoms and superexchange interactions mediated by sulfur p-orbitals are identified as key mechanisms driving these tunable properties. This work highlights self-intercalation as a transformative strategy for engineering high-performance 2D magnetic materials, providing insights for advancing next-generation spintronic devices.