Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 115: Metallic Nanowires on the Atomic Scale (jointly with DS, O)
TT 115.2: Vortrag
Freitag, 20. März 2015, 10:00–10:15, H 2032
Impurity-mediated early condensation of an atomic layer electronic crystal: oxygen-adsorbed In/Si(111)-(4x1)/(8x2) — •Stefan Wippermann1, Wolf Gero Schmidt2, Deok Mahn Oh3, and Han Woong Yeom3 — 1Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany — 2Universität Paderborn, D-33098 Paderborn, Germany — 3Pohang University of Science and Technology, Pohang 790-784, Korea
While impurities have been widely known to affect phase transitions, the atomistic mechanisms have rarely been elucidated. 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 state, a representative electronic phase.
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 ordered ground state, even above the transition temperature. Interestingly, CDW ordering is not induced by single impurities, but instead by the cooperation of multiple impurities. The mechanism is explained as a coherent superposition of the local impurity-induced lattice strain, stressing the coupled electronic and lattice degrees of freedom for CDW ordered phases.