Ultrathin Non-van der Waals Magnetic Rhombohedral Cr2S3: Space-Confined Chemical Vapor Deposition Synthesis and Raman Scattering Investigation

Two dimensional (2D) magnetic materials display enormous application potential in spintronic fields. However, most of currently reported magnetic materials are van der Waals layered structure that is easy to be isolated via exfoliation method. By contrast, the studies on non-van der Waals ultrathin magnetic materials are rare, largely due to the difficulty in fabrication. Rhombohedral Cr2S3, an intensively studied antiferromagnetic transition metal chalcogenide with Neel temperature of approximate to 120 K, has a typical non-van der Waals structure. Restricted by the strong covalent bonding in all the three dimensions of non-van der Waals structure, the synthesis of ultrathin Cr2S3 single crystals is still a challenge that is not achieved yet. Besides, the study on the Raman modes of rhombohedral Cr2S3 is also absent. Herein, by employing space-confined chemical vapor deposition strategy, ultrathin rhombohedral Cr2S3 single crystals with a thickness down to approximate to 2.5 nm for the first time are successfully grown. Moreover, a systematically investigation is also conducted on the Raman vibrations of ultrathin rhombohedral Cr2S3. With the aid of angle-resolved polarized Raman technique, the Raman modes of rhombohedral Cr2S3 for the first time based on crystal symmetry and Raman selection rules are rationally assigned.