Electronic structure reconstruction for √3x√3 charge density wave in heavily Cu-intercalated TiSe2 revealed by spatially resolved photoemission spectroscopy

Scanning photoemission microscopy (SPEM) and angle-resolved photoemission spectroscopy (ARPES) are used to investigate the electronic structure of Cu0.33TiSe2 across the charge density wave (CDW) transition. The electronic structure is found to be largely homogeneous in the normal state above the CDW transition. The ARPES measurements using a submicron beam size reveal a large electronlike pocket due to the Ti 3d band at the M point while the Se 4p band at the point is absent due to electron doping by the intercalated Cu. We have observed √3× √3 Fermisurfacereconstruction below the CDW transition, in which Ti 3d bands are folded into a reconstructed BZ rotated by 30◦ ,making the and K points equivalent. The results demonstrate the presence of a √3× √3 CDW phase in the electronic structure of heavily Cu-intercalated Cu0.33TiSe2. The findings reveal a platform for investigating the two-dimensional electronic phase in 1T-TiSe2 chalcogenides, which exhibit a unique interplay between CDW, superconductivity, and excitonic/lattice instabilities.