Influence of Nitrogen-Cluster States on the Gyromagnetic Factor of Electrons in Gaas1-Xnx

The effective gyromagnetic factor of electrons, g(e)(*), has been determined by Zeeman splitting measurements in a large number of GaAs1-xNx/GaAs (x < 0.7%) samples. Upon N incorporation, g(e)(*) shows first a sign reversal with respect to that of GaAs, then increases abruptly for a nitrogen concentration of order of 0.04%, and finally displays a nonmonotonic dependence on composition for higher x values. This behavior is well reproduced by a modified k center dot p model taking into account a nonmonotonic loss of Gamma character of the conduction band minimum due to multiple crossings between the redshifting conduction band edge and N-cluster states.