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

Article

关键词: RYDBERG EXCITONS;    DEGENERATE BANDS;    FINE-STRUCTURE;    CUPROUS-OXIDE;    ENERGY-BANDS;    SEMICONDUCTORS;    SYMMETRY;    CRYSTALS;    BREAKING;   

DOI  :  10.1103/PhysRevB.94.115201

来源: SCIE

【 摘 要 】

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 hK 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.

【 授权许可】

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