Synthesis, Raman scattering and transport studies of quasi-two-dimensional magnetic Cr2S3 nanoplates

The recent discovery of intrinsic ferromagnetism in atomically thin crystals has sparked a growing effort in synthesizing two-dimensional magnetic materials for new spintronic applications. In this work, we synthesized quasi-two-dimensional Cr₂S₃ nanoplates via a facile sulfurization approach, in which Cr metal was annealed in sulfur atmosphere. Depending on the thickness of Cr layers, the Cr₂S₃ nanoplates were grown either epitaxially or non-epitaxially (i.e. randomly oriented) on the sapphire substrates. Raman scattering studies suggest that both types of nanoplates have a rhombohedral R3 structural phase, which in its bulk form shows weak ferromagnetism below a metal-insulator transition (MIT) temperature (~120K). Density-functional calculations clearly identified most of the Raman-active peaks and their vibrational patterns. The epitaxially grown nanoplates exhibit an enhanced MIT up to ~260 K, while the non-epitaxial sample shows an insulating behavior that can be described by the variable-range-hopping model.