Comparison between ab-initio and phenomenological modeling of the exchange couplings in diluted magnetic semiconductors: the case of $Zn_{1-x}Cr_{x}Te$

摘要

Using a recently developed semi-analytical method (Self-Consistent Local RPAor SC-LRPA) we study the stability of the ferromagnetic phase in dilutedmagnetic systems where the exchange coupling between magnetic impurities are ofRKKY form. A short discussion of the relevance of these calculations withrespect to the ferromagnetism observed in diluted ferromagnetic materials isprovided. Then, within a two step approach, we study ferromagnetism in$Zn_{1-x}Cr_{x}Te$. In the first step of our study, we calculate the magneticcouplings between Mn impurities within the LDA. In the second step, wediagonalize the resulting effective Heisenberg Hamiltonian using the SC-LRPA.We also compare, when available, our calculations with Monte Carlo simulationsand experimental measurements.