K-dependent exchange interaction of the 1S orthoexciton in Cu2O

Frank Schweiner, Jörg Main, Günter Wunner, and Christoph Uihlein
Phys. Rev. B 94, 115201 – Published 12 September 2016

Abstract

When treating the exchange interaction of Wannier excitons, usually only the leading terms of the analytic and the nonanalytic exchange interaction are considered. However, higher-order terms can lead to a splitting of exciton states, for which reason a splitting of the 1S exciton in cuprous oxide Cu2O depending on its total momentum K has been attributed to a K-dependent analytic exchange interaction by Dasbach et al. [Phys. Rev. Lett. 91, 107401 (2003)]. Going beyond the common treatment of the exchange interaction, we derive the correct expressions for these K-dependent higher-order terms using k·p perturbation theory. We prove that the appearance of a K-dependent exchange interaction is inseparably connected with a K-independent exchange interaction of P and D excitons. We estimate the magnitude of these terms for Cu2O from microscopic calculations and show that they are far too small to explain the observed K-dependent splitting. Instead, this splitting has to be treated in terms of the dispersion of the excitons. Furthermore, we prove the occurrence of a coupling between longitudinal and transverse excitons in Cu2O due to the K-dependent nonanalytic exchange interaction.

  • Figure
  • Received 1 July 2016
  • Revised 9 August 2016

DOI:https://doi.org/10.1103/PhysRevB.94.115201

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Frank Schweiner, Jörg Main, and Günter Wunner

  • Institut für Theoretische Physik 1, Universität Stuttgart, 70550 Stuttgart, Germany

Christoph Uihlein

  • Experimentelle Physik 2, Technische Universität Dortmund, 44221 Dortmund, Germany

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Issue

Vol. 94, Iss. 11 — 15 September 2016

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