Fig. 3

Electronic structure of the 4a₀-period commensurate stripe. a Large-scale scanning tunneling microscopy (STM) topography (V = −5.0 V, I = 10 pA, scale bar width 10 nm) showing bidirectional charge stripes, marked by the white dashes. b Typical dI/dV conductance spectra on and off the stripes. Each of them corresponds to the mean of 32 point spectra from the same field of view. Setpoint: V = −2.4 V, I = 100 pA. c Differential conductance maps recorded at different energies as indicated (V = −2.4 V, I = 10 pA, 7 × 7 nm²). d Tunneling current measured as a function of the varied tip-sample distance Δz. Here, a positive Δz means an increased tip-sample distance. As anticipated the tunneling current I reduces exponentially with Δz. e Map (5 × 7 nm²) of local tunneling barrier. As compared to the inter-stripe regions, a larger work function is found on the stripes