Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 30: 1D Metal Wires on Semiconductors I
O 30.2: Vortrag
Dienstag, 8. März 2016, 10:45–11:00, S052
Impurity-mediated early charge density wave condensation in the oxygen-adsorbed In/Si(111)-(4x1)/(8x2) nanowire array — •Stefan Wippermann1, Andreas Lücke2, Wolf Gero Schmidt2, Deok Mahn Oh3, and Han Woong Yeom3 — 1Max-Planck-Institut für Eisenforschung, Düsseldorf — 2Universität Paderborn, Germany — 3Pohang University, South Korea
The self-assembled In/Si(111)-(4x1) nanowire array is an extremely popular model system for one-dimensional electronic systems and features a reversible temperature-induced phase transition into a charge density wave (CDW) ordered ground state. While impurities have been widely known to affect this phase transition, the atomistic mechanisms have rarely been elucidated. Here we present a joint experimental and first principles study, demonstrating oxygen impurity atoms to condense the In/Si(111) nanowire array locally into its CDW ground state, even above the transition temperature. Interestingly, CDW ordering is induced only by a concerted effect of multiple impurities. The mechanism is explained as a subtle interplay between coherent superposition of local impurity-induced lattice strain, a strong coupling between electronic and lattice degrees of freedom, and phononic effects on the free energy. Funding from DFG FOR1700 is gratefully acknowledged.