摘要
Ultrathin Pb and Ge films deposited on Ag(111) surfaces have been investigated and compared. We found that at 1/3 ML, both films formed surface alloys, Ag2Pb and Ag2Ge, with 3×3R30 and 19203×19203R30 structures on Ag(111) but the surface electronic structures exhibit a most evident difference at the Ag(111) surface zone boundary MAg(111), where the single band and the splitting ones were observed, respectively. Up to 1 ML, Ag2Ge subsequently develops into germanene with a striped phase and then a quasifreestanding phase, as previously reported [Lin et al., Phys. Rev. Mater. 2, 024003 (2018)10.1103/PhysRevMaterials.2.024003], while Ag2Pb evolves to a dense Pb(111) phase that also reveals splitting bands at MAg(111). We discover that the larger (smaller) atomic size of a Pb (Ge) atom with respect to an Ag atom causes the commensurate (incommensurate) interfaces and further demonstrate that the splitting bands of Ag2Ge surface alloy and 1-ML Pb film originated from the commonly incommensurate interface with Ag(111), which mediates umklapp scattering by inducing the mirror image of the pristine Ag2Ge and Pb(111) bands relative to MAg(111). © 2019 American Physical Society.