Plasmons in two-dimensional topological insulators

Physical review. B./Physical review. B, vol. 103

Abstract

We analyze collective excitations in models of two-dimensional topological insulators using the random phase approximation. In a two-dimensional extension of the Su-Schrieffer-Heeger model, edge plasmonic excitations with induced charge-density distributions localized at the boundaries of the system are found in the topologically nontrivial phase, dispersing similarly as one-dimensional bulk plasmons in the conventional Su-Schrieffer-Heeger chain. For two-dimensional bulk collective modes, we reveal regimes of enhanced interband wave function correlations, leading to characteristic hardening and softening of inter- and intraband bulk plasmonic branches, respectively. In the two-dimensional Haldane Chern insulator model, chiral, unidirectional edge plasmons in nano-ribbon architectures are observed, which can be characterized by an effective Coulomb interaction cross section. Bulk collective excitations in the two-dimensional Haldane model are shown to be originated by single-particle band structure details in different topological phases.

Authors 3

1. Henning Schlömer Aachen Institute for Theoretical Solid State Physics

   RWTH Aachen University

   Affiliation as printed

   Institute for Theoretical Solid State Physics, RWTH Aachen University, 52056 Aachen, Germany

2. Zhihao Jiang

   University of Southern California

   Affiliation as printed

   Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA

3. Stephan Haas

   University of Southern California

   Affiliation as printed

   Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, USA