  The phase diagram of doped manganate compounds La_{1-x}A_xMnO_3 (with
divalent A) is studied. We analyze an extension of the double exchange model
using the Schwinger boson formalism. Earlier work by de Gennes on the existence
of a canted phase is reproduced, although this phase is shown to be unstable
towards phase separation in a broad regime of physical interest. We numerically
solve the model's mean field equations and plot its phase diagram.
