Electrical conduction through a monatomic surface step

We have succeeded in measuring resistance across a single atomic step at electrical conduction through a monatomic-layer metal on a crystal surface. Using independent methods of direct electrical conductivity measurement with four-tip scanning tunneling microscope probes and scanning tunneling spectroscopy observation, the conductivity across a monatomic step was found to be about $5 \times 10^{3}\,\Omega ^{-1}$m-1. Through analyses of the Landauer formula for 2D conductors and the recent theoretical calculations, the electron transport across an atomic step is fairly modeled as a tunneling process. Important formulas of surface conductivity developed by the present research are given.