Extended Data Fig. 8: Energy dependence of the quasiparticle interference (QPI) near Fermi level.

(a-g) Two-fold symmetrized Fourier transforms (FTs) of differential conductance (dI/dV(r, V)) maps acquired over the same field-of-view on an Sb-terminated surface of sample 1. The dispersive QPI stripes are denoted by magenta (along q_a) and blue (along q_b,c) rectangles. At bias lower than 12 mV, the stripe features along q_a are clearly visible (solid magenta rectangles), while the equivalent features along q_b and q_c are absent (dashed blue rectangles). The trend is reversed at a bias higher than 12 mV. Green circles denote the atomic Bragg peaks. For visual purposes, noise streaks in (c-e) along ~45 degree direction with respect to the horizontal are removed by subtracting a polynomial from each row of the raw dI/dV map before the map is rotated, FT is performed and the FT is two-fold symmetrized. (h,i) Linecuts in FTs of dI/dV(r, V) maps as a function of bias along the magenta and blue dashed lines in (d). Orange curves in (h,i) are visual guides showing the dispersion of QPI wave vectors. STM setup condition: (a) V_sample = 18 mV, I_set = 90 pA, V_exc = 1 mV; (b) V_sample = 16 mV, I_set = 200 pA, V_exc = 1 mV; (c)V_sample = 14 mV, I_set = 100 pA, V_exc = 1 mV; (d)V_sample = 12 mV, I_set = 90 pA, V_exc = 1 mV; (e)V_sample = 10 mV, I_set = 70 pA, V_exc = 1 mV; (f)V_sample = 5 mV, I_set = 60 pA, V_exc = 1 mV; (g)V_sample = −5 mV, I_set = 60 pA, V_exc = 1 mV; T = 4.5 K.