  An isotropic half-metallic double exchange magnet with a direct superexchange
coupling between the localized spins is studied within the spin-wave (1/S)
expansion. The momentum dependence of the spin wave spectrum (including quantum
corrections) in the ferromagnetic phase at T=0 is investigated. Based on the
calculated spin wave spectrum of the canted state, it is shown that as long as
the external magnetic field is not too strong, the double exchange --
superexchange competition does not result in a stabilization of a
two-sublattice canted spin ordering.
