Berlin 2015 – wissenschaftliches Programm
HL 57.1: Vortrag
Mittwoch, 18. März 2015, 16:15–16:30, EW 015
Quantum defect of the Rydberg series for cuprous oxide — •Florian Schöne, Heinrich Stolz, and Stefan Scheel — Universität Rostock MNF/IfPH, 18055 Rostock, Germany
The bound-state energies of semiconductor excitons are commonly described by the hydrogenic Rydberg formula En=−Ry/n2. However, recent experiments in cuprous oxide1 have shown that the energy levels for highly excited p-excitons of the yellow series deviate significantly from the established Rydberg formula. Amongst the possible origins of this deviation, such as frequency-dependent background permittivity and coupling to LO-phonons, the largest contributing factor is the nonparabolic shape of the Γ7+ valence band. Based on the Suzuki-Hensel-Hamiltonian2 which covers spin-orbit and magnetic interactions on symmetry grounds, we are able to analytically describe the nonparabolicity of the valence bands. Applying the concept of quantum defects known from atomic physics, the deviations of the resulting bound-state energies from the hydrogenic Rydberg series can be effectively incorporated in a single parameter δn,l according to En,l=−Ry/(n−δn,l)2. We will show the results for the calculation of the first Rydberg-Ritz parameters for the lowest angular-momentum exciton states of the yellow series of Cu2O.
Kazimierczuk, T. et al., Nature 514, 343-347 (2014)
Suzuki K., Hensel J. C., Phys. Rev. B 9,4184 (1974)