Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 25: Surfaces and films: forces, structure and manipulation

O 25.3: Vortrag

Dienstag, 24. März 2009, 15:30–15:45, SCH A118

Melting of two-dimensional adatom superlattices stabilized by long-range electronic interactions — •N. N. Negulyaev1, V. S. Stepanyuk2, L. Niebergall2, P. Bruno2,3, M. Pivetta4, M. Ternes4,5, F. Patthey4, and W.-D. Schneider41Fachbereich Physik, Martin-Luther-Universität, D06099 Halle, Germany — 2Max-Planck-Institut für Mikrostrukturphysik, D06120 Halle, Germany — 3European Synchrotron Radiation Facility, F38043 Grenoble, France — 4Ecole Polytechnique Federale de Lausanne, CH1015 Lausanne, Switzerland — 5IBM Research Division, Almaden Research Center, San Jose, CA 95120, USA

According to the KTHNY theory [1], a true 2D solid melts to liquid via intermediate phase, named hexatic.

Here we report on a combined experimental and theoretical study of the solid to liquid phase transition of 2D Ce adatom superlattices on Cu(111) and Ag(111) noble metal surfaces. Variable temperature STM measurements and DFT calculations elucidate the formation of the Ce superlattice, while kinetic Monte Carlo simulations describe the temperature dependent Ce adatom coordination within this 2D system [2]. Although the Ce superlattice is stabilized by long-range interactions mediated by surface-state electrons, the substrate atomic potential hinders the existence of the hexatic phase [2]. These results are in agreement with the melting behavior of a 2D lattice in the presence of a 'fine mesh' substrate potential [1].

[1] D.R. Nelson and B.I. Halperin, Phys. Rev. B 19, 2457 (1979).

[2] N.N. Negulyaev et al., Phys. Rev. Lett., submitted.

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