Anisotropic effective mass of orthoexcitons in Cu2O

Abstract

Most of the parameters of the lowest excitons of Cu 2 O (1S excitons of yellow series) are very well known by now. After the experimental determination of the 1S paraexciton mass by two-phonon spectroscopy, a reliable parameter for the determination of orthoexciton masses is now available. Anisotropic mass values are expected for the threefold 1S orthoexciton, because of isotropic and anisotropic k 2 exchange terms. Taking into account the paraexciton mass (2.61 m 0 ) instead of the previously used sum of bare band masses (1.64 m 0 ), earlier orthoexciton mass values have to be revised. Again by two-phonon spectroscopy now of orthoexcitons the only unknown parameter 1 (isotropic k 2 exchange) is determined experimentally, which then allows a reliable determination of orthoexciton mass values in k space.

Optical properties of Rydberg excitons and polaritons

“…[23], [24]). As was shown by Dasbach et al [25] (see also [26]), the total exciton mass in the [0, 0, 1] direction equals 3 m 0 , whereas the value in the [1, 1, 0] direction is equal 0.66 (for example, [7]) or 0.5587 ( [12]), see Table I. The effective mass anisotropy plays an important role in the description of the optical properties of excitons.…”

Biexciton as a Feshbach resonance and Bose–Einstein condensation of paraexcitons in Cu2O

“…The truncation order depends on β value, which cannot be acquired from the band extremum value of electron and hole masses. Because of the exciton considerable spread in momentum space 31 and nonparabolicity of the valence band, 32 both µ h and µ x depend on the wave vector. We take the averaged value of β following from the ratio µ r /µ x = (1 − β)β with reduced mass µ r drawn from the relation E b a 2 x = 2 /2µ r (E b and a x are the exciton binding energy and effective radius, respectively).…”