Fig. 4: Orbital and energy selective enhancement of EPC in Cs(V_0.93Nb_0.07)₃Sb₅.

a Temperature dependence of magnetic susceptibility for pristine CsV₃Sb₅ and Cs(V_0.93Nb_0.07)₃Sb₅. Both zero-field cooling (ZFC) and field cooling (FC) curves are presented. b ARPES intensity plots of the α and β bands along the Γ−Κ direction for Cs(V_0.93Nb_0.07)₃Sb₅. The false color is adjusted for better visualization. c Extracted band dispersions for the α and β bands shown in (b). The black lines are the corresponding bare bands. d Extracted ReΣ(ω) for the α (top panel) and β (bottom panel) bands. The error bars for ReΣ(ω) are determined from the standard deviation of the MDC fits, which is converted to energy by multiplying the velocity of the bare band. The ReΣ(ω) of pristine CsV₃Sb₅ is plotted as colored shadows for a direct comparison. The solid black curves are the reproduced ReΣ(ω) via maximum entropy method. The dashed blue and gray line represents the slope of the ReΣ(ω) at E_F in Cs(V_0.93Nb_0.07)₃Sb₅ and CsV₃Sb₅, respectively. e Extracted Eliashberg function α²F(ω). f EPC strength λ estimated from the α²F(ω), which is plotted as a function of T_c. The error bar for λ is determined by the standard deviation of the ReΣ(ω).