Which chromium-sulfur compounds exist as 2D material?

Affan Safeer; Mahdi Ghorbani-Asl; Wouter Jolie; Arkady V. Krasheninnikov; Thomas Michely; Jeison Fischer

doi:10.1002/adfm.202500907

paper

Which chromium-sulfur compounds exist as 2D material?

arXiv:2501.09510 · doi:10.1002/adfm.202500907

Abstract

Two-dimensional (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 Cr $_{2 \frac{2}{3}}$ S $_{4}$ -2D, which have not been reported before. Cr $_{2 \frac{2}{3}}$ S $_{4}$ -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 $_{2}$ were predicted to be stable by density functional theory calculations and reported in previous experimental studies, we were unable to synthesize CrS $_{2}$ under our range of experimental conditions.