Impact of Next-Nearest-Neighbor hopping on Ferromagnetism in Diluted Magnetic Semiconductors
Abstract
Being a wide band gap system GaMnN attracted considerable interest after the discovery of highest reported ferromagnetic transition temperature TC 940 K among all diluted magnetic semiconductors. Later it become a debate due to the observation of either a ferromagnetic state with very low TC 8 K or sometimes no ferromagnetic state at all. We address these issues by calculating the ferromagnetic window, TC Vs p, within a t-t' Kondo lattice model using a spin-fermion Monte-Carlo method on a simple cubic lattice. We exploit the next-nearest-neighbor hopping t' to tune the degree of delocalization of the free carriers and show that carrier localization (delocalization) significantly widen (shrunken) the ferromagnetic window with a reduction (enhancement) of the optimum TC. We connect our results with the experimental findings and try to understand the ambiguities in ferromagnetism in GaMnN.