Molecular beam epitaxy grown Gal(1-x)Mn(x)As layers were
investigated by means of magnetic resonances. With an increase
in Mn concentration, x, the spectrum changes from the (i)
paramagnetic one, with resolved fine and hyperfine structures,
typical of S = 5/2 spin of substitutional Mn2+ ions, for very
diluted alloy, via (ii) paramagnetic spectrum, where the fine
and hyperfine structures are averaged by a long range Mn2+-Mn2+
exchange coupling, (iii) single, isotropic line of
ferromagnetic resonance. Insulator to metal transition is
accompanied with occurrence of (iv) a very complex spectrum of
the ferrimagnetic resonance, accompanied with the well-resolved
spin wave resonance. Reentrance to insulator phase for the most
condensed alloys is accompanied with the reentrance to (v)
ferromagnetic phase. The data confirm that the effective mass
holes transfer the exchange interaction between localized Mn2+
spins
