Ferromagnetic Transition in $Ge_{1-x}Mn_{x}Te$ Layers

Ferromagnetic transition temperature in thin layers of diluted magnetic (semimagnetic) semiconductor $Ge_{1-x}Mn_{x}Te$ was studied experimentally by SQUID magnetometry method and analyzed theoretically for a model Ising-type diluted magnetic system with Ruderman-Kittel-Kasuya-Yosida indirect exchange interaction. The key features of the experimentally observed dependence of the Curie temperature on Mn content (x ≤ 0.12) and conducting hole concentration p = (1-10) × $10^{21} cm^{-3}$ were reproduced theoretically for realistic valence band and crystal lattice parameters of p-$Ge_{1-x}Mn_{x}Te$ taking into account short carrier mean free path encountered in this material and Ruderman-Kittel-Kasuya-Yosida mechanism with both delta-like and diffused character of spatial dependence of the exchange coupling between magnetic ions and free carriers.