Which Chromium–Sulfur Compounds Exist as 2D Material?

Abstract 2D chromium‐sulfides are synthesized by molecular beam epitaxy using graphene as a substrate. Structure characterization by employing scanning tunneling microscopy and low energy electron diffraction indicates that there are two 2D phases, Cr 2 S 3 ‐2D and 4 ‐2D, which have not been reported before. 4 ‐2D is related to bulk Cr 5 S 6 , but thinner than a bulk unit cell. For Cr 2 S 3 ‐2D, an even thinner material, no bulk counterpart exists. Both 2D materials are found to be structurally stable under ambient conditions and exhibit interesting electronic properties. Extensive first‐principles calculations provide further insight into the electronic structure of these systems and indicate that they should be magnetic. Although single layers of CrS 2 are predicted to be stable by density functional theory calculations and reported in previous experimental studies, CrS 2 is unable to synthesize under the range of experimental conditions.