Fig. 6: Wavelength and angular distribution of CDW.

a Three-dimensional representation of a dI/dV image showing charge modulations on the atomic rows in a false-color scale (acquired at a tunnel voltage of +50 mV). Indicated are the definitions used to measure the wavelength λ and the angle θ describing the spatial correlation of charge modulations in adjacent atomic rows. b Histograms of the distribution of wavelength λ measured at (left) +50 mV and (right) −50 mV tunneling voltage. One can distinguish a peak at λ = 1.2 nm (red lines: Lorentzian fits) and another peak at ~λ = 1.6 nm (gray lines are Gaussian fits) for both tunneling voltages. c Frequency distribution of the angle θ describing the correlation of the charge modulation across the atomic rows in c ([001]) direction. Angles θ can be best described with two Gaussians, centered around −40° and +30°. The presence of two shifted peaks indicate a short-range anti-correlation ordering of parallel CDW stripes along the [001] direction, as schematically illustrated in (d).