ONE-DIMENSIONAL METAL STRUCTURES AT DECORATED STEPS

It is shown how wire structures a few nanometers wide can be fabricated by decorating step edges at vicinal surfaces. Their growth modes and electronic states are studied using Scanning Tunneling Microscopy (STM) and inverse photoemission. The observed growth modes are two-dimensional analogs of Stranski-Krastanov growth and layer-by-layer growth in three dimensions, e.g., for Cu on stepped Mo(1 1 0) and W(1 1 0), respectively. Contrast between different metals is achieved in STM pictures by resonant tunneling via surface states and image states, with the latter providing a map of the work function. The limit of single atomic rows decorating step edges is studied by inverse photoemission, and an energy shift of 0.4 eV is found for electronic states of step atoms. We expect stripe structures to become useful for the study of two- vs one-dimensional magnetism, for magnetoresistive films, and in the design of anisotropic materials.