Figure 2: Nanoscale transport measurements at the sample surface.
From: Electrical resistance of individual defects at a topological insulator surface
(a) Overlay of topography as terrain and potential distribution as colour code. The current density j through the sample is indicated by the red arrows. The topography is dominated by QL steps while in the potential we observe an overall linear voltage slope on the terraces and additional voltage jumps located along lines at the sample surface, for example, the one highlighted by the yellow arrow. Scan size: 300 nm. (b) Topography showing two steps at the sample surface. The section indicated by the solid white line is shown in d. Scale bar, 20 nm. (c) Corresponding potential map with subtracted linear background. Sharp voltage drops are located at the position of topographic steps and along the dotted line which we explain as a domain boundary in the TI film. The corresponding potential section indicated by the solid white line is shown in d. (d) Black line graph: height profile from b. Red line graph: potential section from c. The voltage drops are ΔVstep=0.46(5) mV at the step edge and ΔVDB=1.54(5) mV at the position of the domain boundary (indicated by the vertical dotted line).
