Influence of Domain Walls in the Incommensurate Charge Density Wave State of Cu Intercalated 1T-TiSe2

We report a low-temperature scanning tunneling microscopy study of the charge density wave (CDW) order in 1T-TiSe2 and Cu0.08TiSe2. In pristine 1T-TiSe2 we observe a long-range coherent commensurate CDW (CCDW) order. In contrast, Cu0.08TiSe2 displays an incommensurate CDW (ICDW) phase with localized CCDW domains separated by domain walls. Density of states measurements indicate that the domain walls host an extra population of fermions near the Fermi level which may play a role in the emergence of superconductivity in this system. Fourier transform scanning tunneling spectroscopy studies suggest that the dominant mechanism for CDW formation in the ICDW phase may be electron-phonon coupling.