Finite size effects in surface states of stepped Cu nanostripes

Cu nanostripes with finite arrays of monatomic steps are self-assembled by Ag-induced faceting of vicinal Cu(111) surfaces. By varying the amount of Ag in the submonolayer range one can tune the internal step spacing d of Cu stripes, while decreasing its total width wCu. We can observe, by means of angle-resolved photoemission, a progressive transition from two-dimensional surface bands to one-dimensional quantum well states as wCu decreases. A direct comparison between surface states of infinite vicinals and nanostripes with the same d indicates a small upwards energy shift in the latter, which is well explained by assuming electron confinement in an infinite quantum well of size wCu. Nanostripe finite size effects are more straightforwardly observed in Fermi surfaces, which are asymmetrically broadened in the perpendicular direction. This effect is quantitatively analyzed and explained as due to the characteristic spectral broadening observed in photoemission from wCu-wide one-dimensional quantum wells.This work was supported by the Spanish Ministerio de Ciencia y Tecnología MAT2002-03427, HA2002-0107, MAT-2002-11975-E, FIS2004-06490-C03-03, and, as part of the European Science Foundation EUROCORES Programme SONS, by funds from EC Sixth Framework Programme. The SRC is funded by the National Science Foundation Grant No. DMR-0084402.Peer reviewe