Abstract-Terahertz imaging of Landau levels in HgTe-based topological insulators

Aleksandr M. Kadykov1,2, Jeremie Torres3, Sergey S. Krishtopenko1,2,Christophe Consejo1, Sandra Ruffenach1, Michal Marcinkiewicz1, Dmytro But1, Wojciech Knap1,4, Sergey V. Morozov2,5, Vladimir I. Gavrilenko2,5,Nikolai N. Mikhailov6,7, Sergey A. Dvoretsky6 and Frederic Teppe1,a)

1 Laboratoire Charles Coulomb (L2C), UMR 5221 CNRS–Université de Montpellier, Montpellier, France

2 Institute for Physics of Microstructures, Russian Academy of Sciences, GSP-105, 603950 Nizhny Novgorod, Russia

3 Institut d'Electronique et des Systèmes (IES), UMR 5214 CNRS–Université de Montpellier, Montpellier, France

4 Institute of High Pressure Institute Physics, Polish Academy of Sciences, 01-447 Warsaw, Poland

5 Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod, Russia

6 Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent'eva 13, 630090 Novosibirsk, Russia

7 Novosibirsk State University, 630090 Novosibirsk, Russia

a) Electronic mail: frederic.teppe@umontpellier.fr

http://scitation.aip.org/content/aip/journal/apl/108/26/10.1063/1.4955018

Appl. Phys. Lett. 108, 262102 (2016); http://dx.doi.org/10.1063/1.4955018

We report on sub-terahertz photoconductivity under the magnetic field of a two dimensional topologicalinsulator based on HgTe quantum wells. We perform a detailed visualization of Landau levels by means of photoconductivity measured at different gate voltages. This technique allows one to determine a criticalmagnetic field, corresponding to topological phase transition from inverted to normal band structure, even in almost gapless samples. The comparison with realistic calculations of Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wells than it was assumed previously.