Floquet topological insulators

• Published in: Physica status solidi. PSS-RRL. Rapid research letters Vol. 7; no. 1-2; pp. 101 - 108
• Main Authors: Cayssol, Jérôme, Dóra, Balázs, Simon, Ferenc, Moessner, Roderich
• Format: Journal Article
• Language: English
• Published: Berlin WILEY-VCH Verlag 01.02.2013; WILEY‐VCH Verlag; Wiley Subscription Services, Inc; Wiley-VCH Verlag
• Subjects: Condensed Matter; Electronics; Floquet theory; Other; Physics; Solid state physics; spin-Hall effect; topological insulators; topological insulators; spin-Hall effect; Floquet theory
• ISSN: 1862-6254; 1862-6270
• DOI: 10.1002/pssr.201206451

Topological insulators represent unique phases of matter with insulating bulk and conducting edge or surface states, immune to small perturbations such as backscattering due to disorder. This stems from their peculiar band structure, which provides topological protections. While conventional tools (pressure, doping etc.) to modify the band structure are available, time periodic perturbations can provide tunability by adding time as an extra dimension enhanced to the problem. In this short review, we outline the recent research on topological insulators in non‐equilibrium situations. Firstly, we introduce briefly the Floquet formalism that allows to describe steady states of the electronic system with an effective time‐independent Hamiltonian. Secondly, we summarize recent theoretical work on how light irradiation drives semi‐metallic graphene or a trivial semiconducting system into a topological phase. Finally, we show how photons can be used to probe topological edge or surface states. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) Time‐periodic perturbations, like an electromagnetic wave, could be used to turn a trivial insulator (or a semimetal) into a topological phase. Several recent proposals to realize such nonequilibrium Chern or topological insulators are reviewed in the framework of the Floquet formalism. The authors also review the possibility to use photons in order to probe stationary topological phases like helical edge states (resp. chiral surface states) of 2D (resp. 3D) topological insulators.