Dresden 2017 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 11: Critical phenomena
DY 11.6: Vortrag
Montag, 20. März 2017, 17:00–17:15, HÜL 186
Integer quantum Hall transitions in random Voronoi-Delaunay lattices — •Martin Puschmann1,2, Philipp Cain1, Michael Schreiber1, and Thomas Vojta2 — 1Institute of Physics, Technische Universität Chemnitz, Chemnitz, Germany — 2Department of Physics, Missouri University of Science and Technology, Rolla, Missouri, USA
The random Voronoi-Delaunay lattice (VDL) is a prototypical model for amorphous solids and foams. Bonds between randomly positioned sites are obtained by Delaunay triangulation. The resulting topologically disordered lattice features strong anticorrelations between the coordination numbers of neighboring sites. This modifies the Harris and Imry-Ma criteria and leads to qualitative changes of the scaling behavior at magnetic phase transitions [1]. We have recently shown that for non-interacting electrons on two-dimensional random VDLs all states are still localized and thus this correlated topological disorder is not sufficient to induce a phase transition [2]. Now, we investigate the behavior in presence of a magnetic field. Landau bands are formed by the field and hence phase transitions occur. Based on a recursive Green function approach and the multifractal analysis, we analyze the critical behavior of the lowest Landau level on random VDLs. [1] Barghathi el al., Phys. Rev. Lett. 113, 120602 (2014); [2] Puschmann et al., Eur. Phys. J. B 88, 314 (2015)