A direct observation of the giant Zeeman splitting of the free excitons in (Ga,Fe)N is reported. The magnetooptical and magnetization data imply the ferromagnetic sign and a reduced magnitude of the effective p-d exchange energy governing the interaction between Fe^{3+} ions and holes in GaN, N_0 beta^(app) = +0.5 +/- 0.2 eV. This finding corroborates the recent suggestion that the strong p-d hybridization specific to nitrides and oxides leads to significant renormalization of the valence band exchange splitting.
@article{arxiv.0708.3296,
title = {Observation of strong-coupling effects in a diluted magnetic semiconductor (Ga,Fe)N},
author = {W. Pacuski and P. Kossacki and D. Ferrand and A. Golnik and J. Cibert and M. Wegscheider and A. Navarro-Quezada and A. Bonanni and M. Kiecana and M. Sawicki and T. Dietl},
journal= {arXiv preprint arXiv:0708.3296},
year = {2008}
}