Step-Lattice-Induced Band-Gap Opening at the Fermi Level

Abstract

The interaction of the Shockley surface state with the step lattice of vicinal Cu(111) leads to the formation of an electronic superlattice state. On Cu(443), where the average terrace length forms a ``shape resonance'' with the Fermi wavelength, we find a step-lattice-induced band-gap opening at the Fermi level. A gap magnitude $>200\text{ }\text{ }\mathrm{m}\mathrm{e}\mathrm{V}$ is inferred from high resolution photoemission experiments and line shape analysis. The corresponding energy gain with respect to a gapless case is $\ensuremath{\approx}11\text{ }\text{ }\mathrm{m}\mathrm{e}\mathrm{V}/\mathrm{u}\mathrm{n}\mathrm{i}\mathrm{t}\text{ }\mathrm{c}\mathrm{e}\mathrm{l}\mathrm{l}$, and is a substantial contribution to the stabilization of the step lattice.