Symmetry breaking and circular photogalvanic effect in epitaxial Cd$_x$Hg$_{1-x}$Te films
| Autor: | Hubmann, S., Budkin, G. V., Otteneder, M., But, D., Sacré, D., Yahniuk, I., Diendorfer, K., Bel'kov, V. V., Kozlov, D. A., Mikhailov, N. N., Dvoretsky, S. A., Varavin, V. S., Remesnik, V. G., Tarasenko, S. A., Knap, W., Ganichev, S. D. |
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| Rok vydání: | 2019 |
| Předmět: | |
| Zdroj: | Phys. Rev. Materials 4, 043607 (2020) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevMaterials.4.043607 |
| Popis: | We report on the observation of symmetry breaking and the circular photogalvanic effect in Cd$_x$Hg$_{1-x}$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 non-inverted band structure. We suggest that strain is a reason of 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. Comment: 11 pages, 7 figures |
| Databáze: | arXiv |
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