Intercalation of Cr or Mn in between two VSe₂ van der Waals layers

The insertion of metal layers between layered transition metal dichalcogenides (TMDs) allows the design of pseudo-2D nanomaterials; compared to the host TMDs, these new materials may possess different properties, such as magnetism. In this study, VSe₂ films are grown by van der Waals epitaxy and post-growth metal intercalation is accomplished by vacuum deposition of transition metals (TM), Cr or Mn. These TM atoms intercalate between the VSe₂ layers, and the initial 1×1 structure of VSe₂ systematically changes to a 2×2 and then 2×1 superstructures. DFT calculation predicts that the intercalated TM atoms prefer to occupy the octahedral sites. The energy benefits of inserting TM atoms into the van der Waals (vdW) gap become less with increasing TM concentration. It is observed experimentally that this saturation limit occurs after the formation of 2×1 superstructure when 50% of the intercalation sites are occupied. Further addition of TM atoms results in TM adsorption on the surface. Inserted Cr and Mn atoms have charge states of 3+ and 2+, respectively. Also, magnetic moments for intercalated Cr are high for the dilute Cr regime. A decrease in average magnetic moment is observed with increasing Cr concentration, suggesting antiferromagnetic ordering between Cr ions.