INVESTIGATION OF THE NEUTRAL STATE OF COBALT IMPURITIES IN GALLIUM ARSENIDE.

An investigation was made of the optical absorption and temperature dependence of the magnetic susceptibility in the range 4. 2-300 degree K due to the presence of Co**3** plus (3d**6) ions in gallium arsenide. The optical absorption was typical of photoionization of the acceptor level of cobalt in GaAs located at 0. 16 eV from the top of the valence band. The temperature dependence of the magnetic susceptibility of Co**3** plus in GaAs was in agreement with the crystal field theory as applied to ions with the 3d**6 electron configuration in a field of tetrahedral symmetry. The experimental results were used to estimate the crystal field parameter DELTA and the spin-orbit interaction constant lambda of the Co**3** plus ions in GaAs. The results obtained were compared with those deduced from studies of the magnetic properties of the Fe**2** plus ions in GaAs, which have the same 3d**6 electron configuration.