Photoproduction of long-lived holes and electronic processes in intrinsicelectric fields seen through photoinduced absorption and dichroismin Ca3Ga2−xMnxGe3O12garnets

Abstract

Long-lived photoinduced absorption and dichroism in theCa3Ga2−xMnxGe3O12garnets with x < 0.06were examined versus temperature and pumping intensity. Unusualfeatures of the kinetics of photoinduced phenomena are indicative of theunderlying electronic processes. The comparison with the case of Ca3Mn2Ge3O12,explored earlier by the authors, permits one to finally establish the main commonmechanisms of photoinduced absorption and dichroism caused by random electricfields of photoproduced charges (hole polarons). The rate of their diffusion andrelaxation through recombination is strongly influenced by the same fields, whoselarge statistical straggling is responsible for a broad continuous set of relaxationcomponents (observed in the relaxation time range from 1 to about 1000min). For Ca3Ga2−xMnxGe3O12,the time and temperature dependences of photoinduced absorption anddichroism bear a strong imprint of structure imperfection increasing withx.