Abstract
A microscopic model of indirect exchange interaction between transition metal impurities in dilute magnetic semiconductors (DMS) is proposed. The hybridization of the impurity -electrons with the heavy hole band states is mainly responsible for the exchange of electrons between the impurities, whereas the Hund rule for the electron occupation of the impurity -shells makes it spin selective. The model is applied to such systems as -type (Ga,Mn)N and -type (Ga,Mn)As, -type (Ga,Mn)P. In -type DMS with impurities the exchange mechanism is rather close to the kinematic exchange proposed by Zener for mixed-valence Mn ions. In -type DMS ferromagnetism is governed by the kinematic mechanism involving the kinetic energy gain of the heavy hole carriers caused by their hybridization with electrons of impurities. Using the molecular field approximation, the Curie temperatures are calculated for several systems as functions of the impurity and hole concentrations. Comparison with the available experimental data shows a good agreement.
- Received 23 November 2003
DOI:https://doi.org/10.1103/PhysRevB.70.195215
©2004 American Physical Society