|Terahertz imaging of Landau levels in HgTe-based topological insulators |
Auteur(s): Kadykov A., Torres Jeremie, Krishtopenko S., Consejo C., Ruffenach S., Marcinkiewicz M., But D., Knap W., Morozov Sergey v., Gavrilenko Vladimir i., Mikhailov Nikolai n., Dvoretsky Sergey a., Teppe F.
(Article) Publié: Applied Physics Letters, vol. 108 p.262102 (2016)
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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 levelsby means of photoconductivity measured at different gate voltages. This technique allows oneto determine a critical magnetic field, corresponding to topological phase transition from invertedto normal band structure, even in almost gapless samples. The comparison with realistic calculationsof Landau levels reveals a smaller role of bulk inversion asymmetry in HgTe quantum wellsthan it was assumed previously.