Periodic lattice distortion accompanying the charge-density-wave transition for Sn/Ge(111)

The periodic lattice distortion (PLD) accompanying the charge-density-wave (CDW) transition (at -60 ^∘{}C) in the {α} phase of Sn on Ge(111) has been determined by combining the distinct sensitivities of low-energy electron diffraction (LEED) and surface x-ray diffraction (SXRD). New LEED I-V data combined with a SXRD analysis yield a significant lattice distortion. The PLD accompanying the CDW transition is a 0.37-{} vertical rippling of the Sn atoms accompanied by a perpendicular (0.17 {}) and parallel (0.12 {}) distortion of the first-layer Ge atoms, consistent with a band Jahn-Teller-like distortion.