Extended Data Fig. 5: Analysis for the hexagonal topology.

a, Zoomed-in band dispersion of 0.25 ML K coverage, corresponding to deposition step no. 6 in Fig. 4a. b, Schematic band structure of the ARPES result in a. Blue solid lines schematically show constant energy contours (CECs) at different energies. c, CECs obtained at binding energies of 0, 20, 60, and 80 meV, indicated with the dashed red lines (1–4) in a. d, Symmetrised CECs with 3-fold rotation after removing the intensity from the outer band in c, which reveals the shape of energy contours from the quantum electrons more clearly. Overlaid dashed black lines in c and d are guides for the topology of each CEC. The guidelines evidence that the original shape of contours is not deformed by three-fold symmetrisation. e, Autocorrelation analyses performed with CECs of corresponding energies in d, which clearly visualise the angular dependence of the band along with the in-plane momentum.