Influence of nitrogen-cluster states on the gyromagnetic factor of electrons inGaAs1−xNx

The effective gyromagnetic factor of electrons, ge , has been determined by Zeeman splitting measurements in a large number of GaAs1−xNx /GaAs x 0.7% samples. Upon N incorporation, ge * 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·p model taking into account a nonmonotonic loss of character of the conduction band minimum due to multiple crossings between the redshifting conduction band edge and N-cluster states.