Accurate band mapping via photoemission from thin films

Abstract

Electron bands in solids can be determined in angle-resolved photoemission experiments from thin films, where the perpendicular wave vector ${(k}_{\ensuremath{\perp}})$ uncertainty that characterizes photoemission from bulk crystals is removed. However, the comparison with state-of-the-art quasiparticle band-structure calculations has never been done. In this work we have mapped both initial-state (occupied) and final-state (empty) ${E(k}_{\ensuremath{\perp}})$ bands along the $\ensuremath{\Lambda}$ axis of aluminum, from photon-energy- and thickness-dependent quantum-well spectra of aluminum films. For final states the best fit is obtained with inverse low-energy electron diffraction band structure calculations. For initial-state bands of Cu and Al, thin-film data display excellent agreement with bulk quasiparticle theory, suggesting the use of thin films as model systems to investigate fine effects in the crystal band structure.