Regensburg 2019 – wissenschaftliches Programm
O 95.5: Vortrag
Freitag, 5. April 2019, 11:30–11:45, H14
Temperature induced phase transition of Si(553)-(5x2)-Au in vibrational spectra and its suppression upon step edge hydrogenation — •Eugen Speiser1, Julian Plaickner1, Sandhya Chandola1, Simone Sanna2, Conor Hogan3, and Norbert Esser1 — 1Leibniz-Institut für Analytische Wissenschaften-ISAS- e.V. Schwarzschildstrasse 8, 12489 Berlin, Germany — 2Institut für Theoretische Physik, Heinrich-Buff-Ring 16, 35392 Gießen — 3Istituto di Struttura della Materia-CNR (ISM-CNR), via Fosso del Cavaliere 100, 00133 Rome, Italy
Si(553)-(5x2)-Au is known for its combined structural/electronic phase transition, confirmed by calculations and experiments. Its investigation by vibrational spectroscopies is promising due to their unique sensitivity to atomic scale properties. By comparison to DFT calculations, certain modes in vibrational spectra are assigned to the Si step edge and hence can be used for probing its properties. Indeed, we observe a temperature induced change in vibrational modes at the step edge. The properties of this system are governed by the charge distribution between step edge and Au-chain. As shown previously hydrogenation of the step edge opens the possibility to use it for manipulation of charge distribution. We show that hydrogenation of the step edge suppresses the phase transition related change in vibrational modes. A tentative explanation will be given in terms of thermally induced fluctuation in the charge distribution for the non-hydrogenized surface. This fluctuation is inhibited by additional charge, introduced by hydrogen, suppressing the phase transition.