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The (111) surfaces of noble metals exhibit surface electronic states which disperse parabolically. These pure two-dimensional states can probe fundamental electronic properties
like electron-electron and electron-phonon interactions.
The epitaxial growth of Ag on Cu and Au single crystals leads to artificial electronic systems whose surface state properties can be controlled. As a matter of fact, the surface state energy at the centre of the surface state Brillouin zone can be tuned from -400 meV to -60 meV. The measurements of the spectral width by photoemission and scanning tunnelling spectroscopy allow to test the predictions of the Landau Fermi liquid model, in particular the energy dependence of the quasi-particle lifetime. Moreover, Au (111) surface exhibits two spin-polarized surface subbands due to spin-orbit interaction. In Ag/Au(111), we show that the momentum separation between these two subbands is directly proportional to the amount of Au atoms probed by the surface state demonstrating the atomic character of the spin-orbit interaction in these surface states. Epitaxial growth is a powerful technique to built artificial systems and could be used to prepare quasi-one dimensional electronic systems. |