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Using light as a topological switch: The road towards Floquet topological insulators

TKM Institutsseminar

Speaker:

Luis E. F. Foa Torres

Date:

22/10/2015 14:00

Where:

SEMINARRAUM 10.01. GEB. 30.23 (PHYSIKHOCHHAUS) – CAMPUS SÜD

Affiliation:

CONICET and Universidad Nacional de Córdoba, Argentina

Host:

Dr. Igor Gornyi

Abstract

Light-matter interaction is at the heart of many intriguing phenomena and its understanding has led
to many practical applications like, for instance, Raman spectroscopy. But beyond characterization,
several studies have gone deeper into actually using light to modify the electrical properties of a
material. This can be done, for example, by using light to switch off the conduction in graphene[1,2]
(or other materials [3]), thereby allowing to tune the material's response with optical means, or even inducing tunable topological states in materials that would otherwise lack them [1,2,4,5,6,7,8] (i.e. a Floquet topological insulator). The latter is very promising as it would expand the playground of topological insulators to a broader set of materials. Recently, laser-induced bandgaps have been
experimentally verified at the surface of a topological insulator [3] adding much interest to this area.

In this talk I will provide an overview of the recent developments in this field with a focus on the
generation of Floquet chiral edge states in graphene [6,9], and other materials including
topological insulators [10]. The emergence of a Hall response without Landau levels [11,12] and open problems will also be highlighted.

[1] T. Oka and H. Aoki, Phys. Rev. B 79, 081406 (2009).
[2] H. L. Calvo, H. M. Pastawski, S. Roche, and L. E. F. Foa Torres, Appl. Phys. Lett. 98, 232103 (2011); H. L. Calvo, P. M. Perez-Piskunow, S. Roche, and L. E. F. Foa Torres, Appl. Phys. Lett. 101, 253506 (2012).
[3] Y. H. Wang, H. Steinberg, P. Jarillo-Herrero, and N. Gedik, Science 342, 453 (2013).
[4] N. H. Lindner, G. Refael, and V. Galitski, Nat. Phys. 7, 490 (2011).
[5] T. Kitagawa, T. Oka, A. Brataas, L. Fu, and E. Demler, Phys. Rev. B 84, 235108 (2011).
[6] P. M. Perez-Piskunow, G. Usaj, C. A. Balseiro, and L. E. F. Foa Torres, Phys. Rev. B 89, 121401(R) (2014).
[7] E. Suárez Morell and L. E. F. Foa Torres Phys. Rev. B 86, 125449 (2012).
[8] H. L. Calvo, L. E. F. Foa Torres, P. M. Perez-Piskunow, C. A. Balseiro and G. Usaj, Phys. Rev. B 91, 241404(R) (2015).
[9] G. Usaj, P. M. Perez-Piskunow, L. E. F. Foa Torres, and C. A. Balseiro Phys. Rev. B 90, 115423 (2014); P. M. Perez-Piskunow, L. E. F. Foa Torres and G. Usaj, Phys. Rev. A 91, 043625 (2015).
[10] V. Dal Lago, M. Atala and L. E. F. Foa Torres, Phys. Rev. A 92, 023624 (2015).
[11] L. E. F. Foa Torres, P. M. Perez-Piskunow, C. A. Balseiro, and G. Usaj, Phys. Rev. Lett. 113, 266801 (2014).
[12] Related publications and updates available at http://nanocarbon.famaf.unc.edu.ar/