Quantum interference of bimetallic Pb/Ag films on Si(111)

A previous study on bimetallic Pb/Ag films on Si(111) performed by M. K. Brinkley, et. al. [1] using angle-resolved photoemission (ARPES) revealed a long phase-coherence length throughout the Pb and Ag films. This study verified the electronic coherence by comparing normal emission data with simulation result. However, quantum interference away from the gamma point was not reported. By growing high quality thin films of Pb/Ag/Si(111), whose surfaces were characterized using scanning tunneling microscopy, we found that for a film with an atomically uniform surface, ARPES data revealed clear band structures of Pb/Ag bimetallic system far from the gamma point with fine structures. We investigated the quantum interference between the electronic states originating from the Ag film and those originating from the Pb film. Implications on the superconductor-normal metal proximity effect are also discussed. [1] Brinkley, M. K., et al. Phys. Rev. Lett. 103, 246801 (2009)