Fig. 4. Topological surface states in RbTi₃Bi₅.

a Calculated band structure with (left half) and without surface (right half) states. b The k_//-E ARPES spectra taken along $\overline{K}$-$\overline{\mathrm{\Gamma }}$-$\overline{K}$ direction. c, d Large-scale constant energy k_//-k_z map with photon energies ranging from 50~110 eV along $\overline{K}$-Γ-$\overline{K}$ direction taken at E_F-0.5 eV and E_F-0.9 eV, respectively. Panel (c, d) share the same y-axis The solid lines denote the boundary of Brillouin zones and red arrows denote the topological surface states (TSS). The c in k_z unit represents the out-of-plane lattice constant. e, g The zoomed-in calculated band structure $\overline{K}$ and $\overline{\mathrm{\Gamma }}$ point (red dash boxes I and II in panel a). Panel (e, g) share the same colorbar with panel (a). f, h The zoomed-in 2D curvature ARPES spectra taken around $\overline{K}$ and $\overline{\mathrm{\Gamma }}$ point (red dash boxes I and II in panel b). Panel (f, h) share the same colorbar.