Parts | Days | Selection | Search | Updates | Downloads | Help

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 40: 2D Materials V: Growth, Structure and Substrate Interaction (joint session O/CPP)

CPP 40.8: Talk

Wednesday, March 29, 2023, 16:45–17:00, GER 37

Vanadium sulphides on graphene on Ir(111): polymorphs, charge density waves, layer dependency — •Camiel van Efferen¹, Joshua Hall¹, Virgínia Boix², Tobias Wekking¹, Nikolay Vinogradov³, Alexei Preobrajenski³, Jan Knudsen², Jeison Fischer¹, Wouter Jolie¹, and Thomas Michely¹ — ¹Universität zu Köln — ²Lund University — ³MAX IV Laboratory

Among 2D materials, vanadium based compounds like VS₂ have attracted substantial research interest due to their predicted electronically correlated and magnetic ground states. However, the charge density wave (CDW) in monolayer (ML) VS₂ and VSe₂ competes with predicted magnetic ground states. This has led to new research directions attempting to unlock the magnetic moment of the V atoms, e.g. via defect creation, alloying or the intercalation of atoms between VS₂ layers.

Here, we present a comprehensive X-ray photoemission spectroscopy and scanning tunneling microscopy study of few-layer, quasi-freestanding V₄S₇ and V₅S₈ on Gr/Ir(111), which are created via annealing of stoichiometric VS₂. Annealing ML VS₂ without background S pressure removes S atoms from the top layer of VS₂, creating the striped compound V₄S₇. In contrast, annealing ML VS₂ in a S atmosphere forms V₅S₈, where V atoms have self-intercalated between the VS₂ layers in a 2×2 pattern. Surprisingly, we find that V₅S₈ has a layer-dependent CDW at low temperature, with bilayer V₅S₈ exhibiting a √3×√3 CDW, while the trilayer hosts a striped CDW phase akin to that of ML VS₂.