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

摘要

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