Symmetry breaking and circular photogalvanic effect in epitaxial CdxHg1xTe films

S. Hubmann, G. V. Budkin, M. Otteneder, D. But, D. Sacré, I. Yahniuk, K. Diendorfer, V. V. Bel'kov, D. A. Kozlov, N. N. Mikhailov, S. A. Dvoretsky, V. S. Varavin, V. G. Remesnik, S. A. Tarasenko, W. Knap, and S. D. Ganichev
Phys. Rev. Materials 4, 043607 – Published 28 April 2020

Abstract

We report on the observation of symmetry breaking and the circular photogalvanic effect in CdxHg1xTe 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.

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  • Received 5 November 2019
  • Revised 4 February 2020
  • Accepted 1 April 2020

DOI:https://doi.org/10.1103/PhysRevMaterials.4.043607

©2020 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

S. Hubmann1, G. V. Budkin2, M. Otteneder1, D. But3, D. Sacré1, I. Yahniuk3, K. Diendorfer1, V. V. Bel'kov2, D. A. Kozlov4, N. N. Mikhailov4, S. A. Dvoretsky4, V. S. Varavin4, V. G. Remesnik4, S. A. Tarasenko2, W. Knap3,5, and S. D. Ganichev1

  • 1Terahertz Center, University of Regensburg, 93040 Regensburg, Germany
  • 2Ioffe Institute, 194021 St. Petersburg, Russia
  • 3CENTERA Laboratories, Institute of High Pressure Physics, Polish Academy of Sciences, PL-01-142 Warsaw, Poland
  • 4Rzhanov Institute of Semiconductor Physics, 630090 Novosibirsk, Russia
  • 5Laboratory Charles Coulomb, University of Montpellier and CNRS, Montpellier F-34095, France

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Issue

Vol. 4, Iss. 4 — April 2020

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