Evidence for the existence of hyperbolic excitons has been obtained from a study of the effects of compressive uniaxial stresss on optical structure of GaAs at 77°K using a double-beam wavelength-modulation technique. We have observed a polarization-dependent splitting of this structure which cannot be accounted for on the basis of one-electron band theory but is explained by including the electron-hole exchange interaction. An estimate of an effective radius of ≅10 Å for the electron-hole interaction has been made.

• Received 11 February 1969

DOI:https://doi.org/10.1103/PhysRevLett.22.933