Fig. 2: Evidence of electronic structure reconstruction in KV₃Sb₅.

a Fermi surface mapping of KV₃Sb₅ at 20 K in the CDW phase. In addition to the original Fermi surface, some extra weak features can be observed as marked by arrows and guided by the dashed lines that are reconstructed Fermi surface due to the CDW wavevector Q₁. b Schematic of the reconstructed Fermi surface of KV₃Sb₅ due to CDW wavevector Q₁. The solid lines represent the original Fermi surface sheets. The reconstructed Fermi surface sheets (dashed lines) are obtained by shifting the original Fermi surface with a wavevector ±Q₁. c Band structure measured along the \(\bar{{{\Gamma }}}\)-\(\bar{M}\) high-symmetry direction at 20 K. The location of the momentum cut is marked as a solid pink line in a. Around \(\bar{{{\Gamma }}}\) just below the Fermi level, some extra bands can be observed. d The momentum distribution curve (MDC) at the Fermi level from the band structure in c. Two MDC peaks (β_L and β_R) can be observed around \(\bar{M}\), and another two MDC peaks (\({\beta }_{{{{{{\mathrm{L}}}}}}}^{\prime}\) and \({\beta }_{{{{{{\mathrm{R}}}}}}}^{\prime}\)) can be observed around \(\bar{{{\Gamma }}}\). The separation between β_L and \({\beta }_{{{{{{\mathrm{L}}}}}}}^{\prime}\) (β_R and \({\beta }_{{{{{{\mathrm{R}}}}}}}^{\prime}\)) corresponds to the reconstruction wavevector Q₁. e The photoemission spectra (energy distribution curves, EDCs) measured at \(\bar{{{\Gamma }}}\) and \(\bar{M}\) points in c. They show similar EDC lineshape in the low binding energy region (E_B < 0.3 eV). f Fermi surface mapping of KV₃Sb₅ at 20 K in the CDW phase measured by laser-ARPES. Some extra weak features can be observed as marked by the dashed lines that are reconstructed Fermi surfaces due to the CDW wavevector Q₁. g–i Band structures along the momentum cut marked as a black line in f measured at 40 K (g), 80 K (h), and 120 K (i).