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TT: Fachverband Tiefe Temperaturen

TT 1: Topological Insulators 1 (joint session TT/HL)

TT 1.4: Vortrag

Montag, 16. März 2020, 10:15–10:30, HSZ 03

Topology and boundary physics in one dimensionional insulators — •Herbert Schoeller, Niclas Müller, Dante Kennes, and Mikhail Pletyukhov — RWTH Aachen University, Germany

Alternative to the characterization of topological insulators in terms of mathematical invariants we present a practical version via the explicit solution of the Schrödinger equation for a generic half-infinite system in one dimension. We show how the boundary condition can be fulfilled by taking appropriate linear combinations of Bloch eigenstates for the infinite system with complex quasimomentum [1]. Via this scheme all edge and bulk states can be explicitly constructed. In the presence of chiral or particle-hole symmetry the existence and stability of zero-energy edge states together with the bulk-boundary correspondence is established, proving the consistency with the standard classification scheme. Without symmetry constraints, we find generically edge states at finite energy in the gap and show that many bulk states are superpositions of Boch waves and exponentially decaying parts, implying interesting boundary physics at finite energy [2].

[1] D.M. Kennes et al., Phys. Rev. B 100, 041103 (2019).

[2] N. Müller et al., arXiv:1911.02295.