Nature of the broken-symmetry phase of the one-dimensional metallic In/Si(111) surface

Abstract

The phase transition of a metallic In chain structure on Si(111) was investigated by high-resolution photoemission. Core-level spectra clearly elucidate that the symmetry breaking at low temperature occurs only within the inner parts of the In chains. In the valence bands, the transition is accompanied by the formation of pseudogaps of 80–150 meV and the band backfolding with only marginal changes of the band dispersion. No sign of Luttinger liquid behavior is observed in the spectral function near the Fermi level. This result is generally consistent with the idea of a fluctuating one-dimensional charge-density wave state but conflicting with the present structure model for the low-temperature phase

Surface structure of Si(111)-(8×2)–In determined by reflection high-energy positron diffraction

“…Therefore, the 8 Â 2 surface composed of the trimer structure has a metallic character. This result contradicts the surface electronic conductivity [9] and the ARUPES measurements [15]. These measurements suggests the gap opening, the values of the band gap are estimated as about 300 meV [9] and 80-150 meV [15], respectively.…”

“…To determine the structure of In atomic chains at low temperatures, many extensive studies have been carried out using scanning tunneling microscopy (STM) [10][11][12][13][14], photoemission spectroscopy (PES) [15,16], high-resolution electron-energy-loss spectroscopy (HREELS) [17], low-energy electron diffraction (LEED) [18], surface X-ray diffraction (SXRD) [19], and first-principles calculation [20][21][22]. Most of the results support the fact that at low temperatures, In atomic chains consist of trimers, as shown in Fig.…”

Surface structure of In/Si(111) studied by reflection high-energy positron diffraction

“…The other studies such as scanning tunneling microscopy (STM) [2], angle-resolved photoelectron spectroscopy (ARPES) [8], inverse photoelectron spectroscopy (IPES) [9], reflectance anisotropy spectroscopy (RAS) [10], XRD [11], low-energy electron diffraction (LEED) [12], and ab-initio calculations [13][14][15][16][17] confirmed this zigzag chain model. The 4 · 1 and 8 · 2 phases show metallic and insulating features, respectively [3][4][5]8,[18][19][20]. Thus, this phase transition is considered to be metal-insulator transition [4,20].…”

Quantum conductance of In nanowires on Si(111) from first principles calculations

“…While the RT 4 · 1 phase is a quasi-1D metal [18] that gives rise to electron transport attributed to In related surface states [19,12,18], many experimental studies conclude that the phase transition leads to a fundamental energy gap of 0.1-0.3 eV [11][12][13][14]. Others only state a reduced density of states at the Fermi energy (E F ) [17,20,15] or remain inconclusive [21]. In any event, the electron conduction through the nanowires ceases for the LT phase [19,12] and the Drude tail in high-resolution electron-energy loss spectra is drastically reduced [22].…”