Photoemission study of twisted monolayers and bilayers of WSe2 on graphite substrates

Using microfocused angle-resolved photoemission spectroscopy we investigated microstructures containing regions of single-layer (SL) and bilayer (BL) ${\mathrm{WSe}}_2$ on graphite substrates at different twist angles between SL ${\mathrm{WSe}}_2$ and graphite and within the BL ${\mathrm{WSe}}_2$. Fermi level electrons emitted from the graphite are sharply focused near their $K{}_{gr}$ points in the Brillouin zone, and, when passing through the ${\mathrm{WSe}}_2$, get diffracted to form band replicas readily observed in experimental Fermi surface maps from twisted SL ${\mathrm{WSe}}_2$/graphite. We investigated two twisted BL ${\mathrm{WSe}}_2$ at twist angles $\sim {28}^{\circ }$ and $\sim {10}^{\circ }$ and found no evidence of hybridization gaps at the interlayer band-crossing points, that could be precursors of the flat bands at smaller twist angles. Similarly, no such gaps were found for SL ${\mathrm{WSe}}_2$/graphite. Experimental results are complemented by theoretical density functional theory calculations, which suggest that a formation of hybridization gaps in the ${\mathrm{WSe}}_2$/graphene (which approximates the experimental ${\mathrm{WSe}}_2$/graphite system) sensitively depends on the ${\mathrm{WSe}}_2$ band character at the crossing point with the graphene Dirac band.