Phonon softening, chaotic motion, and order-disorder transition in Sn/Ge(111)

The phonon dynamics of the Sn/Ge(111) interface is studied using high-resolution helium atom scattering and first-principles calculations. At room temperature we observe a phonon softening at the Kmacr; point in the (sqrt[3]xsqrt[3])R30 degrees phase, associated with the stabilization of a (3x3) pha...

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Published inPhysical review letters Vol. 91; no. 1; p. 016103
Main Authors Farías, D, Kamiński, W, Lobo, J, Ortega, J, Hulpke, E, Pérez, R, Flores, F, Michel, E G
Format Journal Article
LanguageEnglish
Published United States 04.07.2003
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Summary:The phonon dynamics of the Sn/Ge(111) interface is studied using high-resolution helium atom scattering and first-principles calculations. At room temperature we observe a phonon softening at the Kmacr; point in the (sqrt[3]xsqrt[3])R30 degrees phase, associated with the stabilization of a (3x3) phase at low temperature. That phonon band is split into three branches in the (3x3) phase. We analyze the character of these phonons and find out that the low- and room-temperature modes are connected via a chaotic motion of the Sn atoms. The system is shown to present an order-disorder transition.
ISSN:0031-9007
DOI:10.1103/PhysRevLett.91.016103