  The relative stability among the multiple spin density wave (MSDW) states in
fcc transition metals has been investigated on the basis of a Ginzburg-Landau
type of free energy with terms up to the fourth order in magnetic moments.
Obtained magnetic phase diagrams in the space of expansion coefficients
indicate the possibility of various 3Q MSDW states in fcc transition metals:
the commensurate 3Q state, the incommensurate linear 3Q state, and the
incommensurate helical 3Q state. It is shown that these 3Q states are always
stabilized, when they are compared with the corresponding 2Q and 1Q states, and
their magnetic moment amplitudes are the largest among those of the three
states. The results are compared with previous results of the ground-state
calculations, and possible scenarios to explain the experimental data of fcc-Fe
are proposed.
