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 {minus}60h{degree}C) in the {alpha} 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-{Angstrom} vertical rippling of the Sn atoms accompanied by a perpendicular (0.17 {Angstrom}) and parallel (0.12 {Angstrom}) distortion of the first-layer Ge atoms, consistent with a band Jahn-Teller-like distortion. {copyright} {ital 1999} {ital The American Physical Society}