Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 99: Scanning Probe Methods III
O 99.7: Vortrag
Freitag, 4. April 2014, 12:00–12:15, GER 38
Modifying the atomic structure of a single Pb layer by STM — •Michael Caminale1, Augusto A. Leon Vanegas1, Agnieszka Stepniak1, Hirofumi Oka1, Dirk Sander1, and Jürgen Kirschner1,2 — 1MPI-Halle — 2MLU Halle-Wittenberg
The highly complex atomic structure of one single layer of Pb on Si(111) has been extensively investigated in the past by scanning tunneling microscopy (STM) [1-2]. It has been shown that in a narrow coverage interval of 0.1 ML the system exhibits a quasi-infinite number of structural phases constructed hierarchically with an increasing atomic density. This is ascribed to the existence of two competing unit cells for the Pb atoms, respectively identified as √3×√3 (10.44 atoms/nm2) and √7×√3 (9.4 atoms/nm2). The combination of these leads to a rich set of phases [2]. We report the manipulation of a structural phase of Pb/Si(111) by STM-induced structural manipulation at 380 mK. A reversible modification of the atomic arrangement on a scale from 15×15 nm2 to 80×80 nm2 is achieved by exploiting the tip-surface interaction by two different strategies: (i) by the application of a milliseconds-long voltage pulse for a constant tunneling current; (ii) by a milliseconds-long ramping of the tip-surface distance for a constant bias value. Combined atomically resolved STM and tunneling spectroscopy measurements give a structural and electronic characterization of the phase change. The results are discussed in view of tip-surface interactions, mass transfer and surface atomic diffusion.
[1] D. R. Heslinga et al. Phys. Rev. Lett. 64, 1589 (1990). [2] M. Hupalo et al. Phys. Rev. Lett. 90, 216106 (2003).