Absence of dynamic fluctuation in metallic In chains on Si(111): Core-level and valence-band photoemission study

We have studied in detail the evolution of the metal-insulator transition with temperature for the (4×1)-In chain structure on Si(111) using core-level and valence-band photoemission spectroscopy. Photoemission spectra unambiguously reveal that the high- and low-temperature phases are distinct with well-separated and characteristic spectral features. No sign of extra broadening or change of the spectral features was observed above the well-defined critical temperature. This result clearly rules out the existence of any dynamic fluctuation for the high-temperature metallic phase in contradiction with a recent theory [Phys. Rev. Lett. 96, 136101 (2006)].