Figure 2: STS and bias voltage-dependent corrugation.

(a) Topography of the Fe double layer on Rh(001) and (b–e) dI/dU maps taken at the indicated bias voltages from constant-separation STS data (setpoint parameters: U=+1.0 V, I=500 pA). The stripe pattern is only visible in the occupied energy range. Image sizes are 15 × 15 nm². (f) Tunnelling spectra measured along the box in d. The peak at −0.2 V is more intensive on the bright stripes than between them. (g) Plot of the electronic asymmetry as a function of bias voltages. Although the electronic asymmetry is negligible in the empty states, it becomes maximal in the occupied states at about −0.2 V. (h,i) Topographic images taken at U=+0.6 V and −0.6 V. Scale bars, 5 nm. (j) Averaged line sections measured along the red and black lines. (k) Bias dependence of the corrugation. Error bars are given by standard deviation of corrugation peak heights measured at corresponding bias voltages.