Low-temperature scanning tunneling microscopy of ring-like surface electronic structures around Co islands on InAs(110) surfaces

TL;DR

This paper uses low-temperature scanning tunneling microscopy to observe and explain ring-like electronic structures around Co islands on InAs(110), revealing interference effects in electron tunneling.

Contribution

It introduces a theoretical model accounting for non-equilibrium effects to explain the observed ring-like features in tunneling spectroscopy.

Findings

Ring-like features appear around Co islands at specific bias voltages.

Features are explained by interference between direct and indirect tunneling paths.

The model successfully accounts for the observed spectroscopic phenomena.

Abstract

We report on the experimental observation by scanning tunneling microscopy at low temperature of ring-like features that appear around Co metal clusters deposited on a clean (110) oriented surface of cleaved p-type InAs crystals. These features are visible in spectroscopic images within a certain range of negative tunneling bias voltages due to the presence of a negative differential conductance in the current-voltage dependence. A theoretical model is introduced, which takes into account non-equilibrium effects in the small tunneling junction area. In the framework of this model the appearance of the ring-like features is explained in terms of interference effects between electrons tunneling directly and indirectly (via a Co island) between the tip and the InAs surface.