Quantum coherence effects in the scanning tunneling microscope: a simple interpretation of contact resistance experiments

Quantum coherence effects that arise in the scanning tunneling microscope ( STM) when the tip is brought in close proximity to the substrate are addres sed on the basis of a recently reported theory in which a continuous transi tion from an incoherent regime at large gap distances to a coherent regime at short distances is described by means of electron propagators. A simple model of the STM junction is introduced, and is shown to provide a simple a nd intuitive explanation for the appearance of plateau and a jump in the cu rrent characteristics. (C) 1999 Elsevier Science B.V. All rights reserved.