Low-dimensional systems on self-structured metal surfaces

One-dimensional electronic systems on metal surfaces can be obtained e.g. by step decoration, lateral confinement in stress domains or by self-assembled adsorbate-chain systems. With Pt(1 1 0) serving as a template, a monolayer of Pt–halogen–Pt chains can be grown. This is a surface-analog of halogen-bridged transition-metal chain molecules. Similar to the latter, the halogen/Pt monolayer develops a charge density wave (CDW) phase if suitably doped. The transition into the CDW groundstate is directly observed by scanning tunnelling microscopy (STM). The Fermi surface determined from angle-resolved UV-photoemission (ARUPS) is consistent with the CDW structure observed by STM. Close to EF, ARUPS spectra are dominated by many-body effects. Different doping allows to switch between randomly pinned, chaotic soliton and globally ordered CDW phases.