Regensburg 2010 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Nanostructures at surfaces: arrays
O 33.6: Vortrag
Dienstag, 23. März 2010, 16:15–16:30, H31
Terrace-Width Distributions (TWDs) of Touching Steps: Modification of the Fermion Analogy, with Implications for Measuring Step-Step Interactions on Vicinal Surfaces* — •Theodore L. Einstein1, Rajesh Sathiyanarayanan1,2, Ajmi BH. Hamouda1,3, and Kwangmoo Kim1 — 1U. Maryland, College Park, USA — 2Pennsylvania State U., USA — 3Monastir U., Tunisia
Using Monte Carlo simulations, we compute1 the TWDs of surfaces in which steps can touch each other, forming multiple-atomic height steps, but cannot cross (no overhangs), and so inconsistent with the standard mapping to spinless fermions. Our numerical results show that the generalized Wigner distribution, with minor modifications at small step separations, gives a very good fit for TWDs of touching steps. (We also generate analytic results by generalizing results for extended fermions.2) The interaction strength derived from the fit parameter ϱ indicates an effective attraction between steps, weakening the overall repulsion. The strength of this effective attraction decreases for larger mean-step separations and decreasing step-touching energies; describable via finite-size scaling. Hence, accurate extraction of the true repulsion strength requires multiple vicinalities.
*Supported by UMD NSF MRSEC Grant DMR 05-20471
1RS, ABH, and TLE, Phys. Rev. B 80 (2009) 153415.
2Siew-Ann Cheong and C.L. Henley, arXiv:0907.4228v1.