Symmetry breaking and circular photogalvanic effect in epitaxial CdxHg1-xTe films
| Autor: | N. N. Mikhailov, V. G. Remesnik, V. S. Varavin, Stefan Hubmann, Wojciech Knap, S. A. Dvoretsky, M. Otteneder, D. A. Kozlov, G. V. Budkin, Dmytro B. But, I. Yahniuk, Sergey Ganichev, V. V. Bel'kov, Daniel Sacré, Sergey Tarasenko, K. Diendorfer |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
| Předmět: |
Photocurrent
Photon Materials science Physics and Astronomy (miscellaneous) Condensed matter physics ddc:530 02 engineering and technology 021001 nanoscience & nanotechnology 530 Physik 01 natural sciences Symmetry (physics) Condensed Matter::Materials Science Excited state 0103 physical sciences General Materials Science Symmetry breaking Absorption (logic) 010306 general physics 0210 nano-technology Electronic band structure Surface states |
| Popis: | We report on the observation of symmetry breaking and the circular photogalvanic effect in ${\mathrm{Cd}}_{x}{\mathrm{Hg}}_{1\ensuremath{-}x}\mathrm{Te}$ alloys. We demonstrate that irradiation of bulk epitaxial films with circularly polarized terahertz radiation leads to the circular photogalvanic effect (CPGE) yielding a photocurrent whose direction reverses upon switching the photon helicity. This effect is forbidden in bulk zinc-blende crystals by symmetry arguments; therefore, its observation indicates either the symmetry reduction of bulk material or that the photocurrent is excited in the topological surface states formed in a material with low cadmium concentration. We show that the bulk states play a crucial role because the CPGE was also clearly detected in samples with noninverted band structure. We suggest that strain is a reason for the symmetry reduction. We develop a theory of the CPGE showing that the photocurrent results from the quantum interference of different pathways contributing to the free-carrier absorption (Drude-like) of monochromatic radiation. |
| Databáze: | OpenAIRE |
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