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URN: urn:nbn:de:bsz:25-opus-25326
URL: http://www.freidok.uni-freiburg.de/volltexte/2532/

Urban, Daniel F.

Stability, symmetry breaking, and scaling properties of metallic nanowires

Stabilität, Symmetriebrechung und Skalierungseigenschaften metallischer Nanodrähte

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Kurzfassung in Englisch

In this thesis, a quantum mechanical stability analysis of metallic nanowires within the Nanoscale Free Electron Model is presented, whereby wires of various cross-sectional shapes are considered. It is found that the stability is determined by an interplay of electron-shell effects, the Rayleigh instability due to surface tension, and the Peierls instability. Using the scattering matrix formalism, we derive the change in energy due to small deformations of the initial geometry. Our results prove the existence of certain stable magic radii like they have been found in experiments and give an explanation for the cylindrical geometry of the nanowires observed mostly.

The Peierls instability in metal nanowires is discussed. We study the onset of the charge density wave transition with increasing wire length, where the newly arising length scale is set by the size of the gap. The singular part of the electronic energy is found to obey a set of scaling relations consistent with a hyperscaling ansatz.

Furthermore, we show that a Jahn-Teller deformation breaking cylindrical symmetry can be energetically favorable, leading to stable nanowires with elliptical cross-sections. The sequence of stable cylindrical and elliptical nanowires allows for a consistent interpretation of the experimental conductance histograms for alkali metals, including both the electronic shell and supershell structures. An extension of the linear stability analysis to wires with general cross-sectional shapes is also presented.

SWD-Schlagwörter: Nanodraht , Stabilität , Symmetriebrechung , Peierls-Instabilität , Jahn-Teller-Effekt
Freie Schlagwörter (deutsch): Elektronenschaleneffekt
Freie Schlagwörter (englisch): Nanowire , Stability , Symmetry Breaking , Peierls-Instability , Jahn-Teller-effect , Electron-shell-effect
Institut: Physikalisches Institut
Fakultät: Fakultät für Mathematik und Physik
DDC-Sachgruppe: Physik
Dokumentart: Dissertation
Erstgutachter: Grabert, Hermann (Prof. Dr.)
Sprache: Englisch
Tag der mündlichen Prüfung: 15.02.2006
Erstellungsjahr: 2006
Publikationsdatum: 20.07.2006