Fermi contour imaging of the two-dimensional semimetalErSi2by Fourier transform STM

Abstract

Using low-temperature scanning tunnelling microscopy we study the two-dimensional (2D) ${\mathrm{ErSi}}_{2}$ layer grown on Si(111) $7\ifmmode\times\else\texttimes\fi{}7$ substrates. We report on a high atomic resolution that nicely confirms in direct space the previously determined atomic model structure. But more importantly this semimetallic system provides ideally confined 2D electron and hole gases which, by imaging at low bias voltage and low temperature (77 K), give rise to complex standing wave patterns. Using Fourier transform of such standing wave patterns, the whole Fermi contour appears to be involved and both hole and electron pocket features are evidenced. The consistency of our new results with previous photoemission studies is discussed.