Direct determination of symmetry of Cr ions in semi-insulating GaAs substrates through anisotropic ballistic-phonon propagation and attenuation

Abstract
We report ballistic phonon experiments in semi‐insulating GaAs as a function of polarization and propagation direction and of the concentration of chromium in the crystal. The data provide direct evidence for a tetragonally distorted site symmetry of the Cr ions and a ground‐state splitting at ∼14 K.