2017/08/31 by Bastian Höckendorf, Andreas Alvermann, Holger Fehske · 1 citation
Physics and Astronomy · #cond-mat.mes-hall
paper · pdf · doi:10.1103/physrevb.97.045140
published as Phys. Rev. B 97, 045140 (2018) · 12 pages, 9 figures. Final version as published
arxiv created 2018/01/23 · arxiv updated 2018/01/24
We introduce \mathbb Z2-valued bulk invariants for symmetry-protected topological phases in 2+1 dimensional driven quantum systems. These invariants adapt the W3-invariant, expressed as a sum over degeneracy points of the propagator, to the respective symmetry class of the Floquet-Bloch Hamiltonian. The bulk-boundary correspondence that holds for each invariant relates a non-zero value of the bulk invariant to the existence of symmetry-protected topological boundary states. To demonstrate this correspondence we apply our invariants to a chiral Harper, time-reversal Kane-Mele, and particle-hole symmetric graphene model with periodic driving, where they successfully predict the appearance of boundary states that exist despite the trivial topological character of the Floquet bands. Especially for particle-hole symmetry, combination of the W3 and the \mathbb Z2-invariants allows us to distinguish between weak and strong topological phases.