Fig. 3

Data frame construction and essential variable extraction from the photoemission data. (a) Crystal structure of CsV₃Sb₅. (b) Side view of the crystal structure with Cs- and Sb-terminated surfaces. (c) Schematics of the procedure to construct the input data frame in this study. In panel c3, a representative photoemission spectrum (dots) for the Cs 4d core levels is displayed, with the result of numerical fittings (solid curves) with four Lorentzian peaks and a linear background. Peak 1 and 3 represent spin-orbit partners for surface-derived peaks, while peak 2 and 4 represent those for bulk-derived peaks. (d) Spatial mapping of total spectral weight of peak 1 for Cs core levels, which highlights the existence of Cs-rich (red) and Sb-rich (blue) domains. (e) Correlation matrix for all the variables, i.e. spectral weight and peak energy for Cs core levels (I_Cs1-I_Cs4 and E_Cs1-E_Cs4, respectively) and those for Sb core levels (I_Sb1-I_Sb2 and E_Sb1-E_Sb2, respectively), together with their background intensity (B_Cs and B_Sb). (f-i) Scatter plots of (I_Cs1, I_Cs3), (E_Sb1, E_Sb2), (I_Sb1, I_Sb2), and (E_Cs1, I_Cs1) pairs, respectively. In (i), data points corresponding to Cs-rich, intermediate, and Sb-rich regions are indicated by red, green, and blue dots, respectively (see Fig. 5b).