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Topological Edge States with Zero Hall Conductivity in a Dimerized Hofstadter Model
Alexander Lau1, Carmine Ortix1,2, Jeroen van den Brink1,3
1Institute for Theoretical Solid State Physics, IFW Dresden, 01171 Dresden, Germany.
Abstract:
The Hofstadter model is a simple yet powerful Hamiltonian to study quantum Hall physics in a lattice system, manifesting its essential topological states. Lattice dimerization in the Hofstadter model opens an energy gap at half filling. Here we show that even if the ensuing insulator has a Chern number equal to zero, concomitantly a doublet of edge states appear that are pinned at specific momenta. We demonstrate that these states are topologically protected by inversion symmetry in specific one-dimensional cuts in momentum space, define and calculate the corresponding invariants, and identify a platform for the experimental detection of these novel topological states.
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