Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 56: Poster Session: Low-Dimensional Systems

TT 56.5: Poster

Mittwoch, 22. März 2017, 15:00–19:00, P2-OG4

Correlation length in topological insulators: how different are a mug and a donut? — •Wei Chen, Markus Legner, Andreas Rüegg, and Manfred Sigrist — ETH Zurich, Zurich, Switzerland

We all know that a mug and a donut have the same topology. But how different are they? How different are two topological insulators that have the same topological invariant? We show that the correlation function that characterizes the topological insulators in 1D is a charge polarization correlation between Wannier states, and in 2D it is an itinerant circulation correlation between Wannier states. Suprisingly, these Wannier state correlation functions are nonzero in both topologically trivial and nontrivial states. The correlation function allows to extract a correlation length that characterizes the difference between topological insulators that are close to those that are far away from the topological phase transitions. The critical exponent of correlation length further suggests the existence of universality classes.