Hamburg 2001 – wissenschaftliches Programm

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SYGS: 30 Jahre Gutzwiller Spurformel

SYGS III: HV III

SYGS III.1: Hauptvortrag

Mittwoch, 28. März 2001, 15:30–16:00, S6

Cohesion and Stability of Metal Nanowires: A Quantum Chaos Approach — •Charles A. Stafford — University of Arizona, Tucson, USA

A remarkably quantitative understanding of the electrical and mechanical properties of metal wires with a thickness on the scale of a nanometer has been obtained within the free-electron model using semiclassical techniques. Convergent trace formulas for the density of states and cohesive force of a narrow constriction in an electron gas, whose classical motion is either chaotic or integrable, are derived. Mode quantization in a metallic point contact or nanowire leads to universal oscillations in its cohesive force, whose amplitude depends only on a dimensionless quantum parameter describing the crossover from chaotic to integrable motion, and is of order 1 nN, in agreement with experiments on gold nanowires. A linear stability analysis shows that the classical instability of a long wire under surface tension can be completely suppressed by quantum effects, leading to stable cylindrical configurations whose electrical conductance is a magic number 1, 3, 5, 6,... times 2e²/h, in accord with recent results on alkali metal nanowires.