Targeted Dy intercalation under graphene/SiC for tuning its electronic band structure

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Metal intercalation of graphene is a promising method to tune its electronic band structure and generate novel electronic and topological phases. The tuning depends critically on the ability to bond the intercalated atoms at predesigned, subsurface interlayer locations because the emerging band structure depends on metal location. We have studied Dy intercalation under single-layer graphene (SLG) on SiC using spot profile analysis--low-energy electron diffraction and scanning tunneling microscopy (STM). The experimental work is complemented with density-functional theory (DFT) analysis. Because different diffraction spots originate from different subsurface interlayer regions, it is possible to identify changes in the intercalation location by monitoring the spot intensity as a function of growth conditions. DFT calculations of the chemical potential as a function of intercalated Dy coverage support the variation of the stability of the intercalated phase at different intercalated locations. The preferred location is confirmed from STM studies showing the removal of the $6\ifmmode\times\else\texttimes\fi{}6$ moir\'e corrugation at the preferred location, observed at higher Dy coverage.