MAGNETIC LOCALIZATION OF FREE-EXCITON MAGNETIC POLARONS IN DILUTED MAGNETIC SEMICONDUCTORS

A model of free exciton magnetic polarons (EMPs) in diluted magnetic s emiconductors is proposed on the basis of the localization of the hole in the magnetic potential well created by its own exchange field. The corresponding calculations of the free EMP binding energies, as a fun ction of Mn2+ ion concentration and temperature, are performed. The re sults are in good agreement with recent experimental measurements. It is found that free EMPs are stable up to relatively high temperatures (T less than or similar to 30 K) over a wide range of Mn concentration s x without any other primary localization, e.g., alloy potential fluc tuations. The dependence of the critical temperature of free EMP forma tion on the Mn concentration is determined for various diluted magneti c semiconductor materials, and is in good agreement with the experimen tal results for Cd1-xMnxTe. The suppression of free EMPs under the app lication of an external magnetic field is also considered. (C) 1997 Am erican Institute of Physics.