SOME ASPECTS OF THE PHASE-DIAGRAM OF DOUBLE-EXCHANGE SYSTEMS

The phase diagram of doped manganate compounds La(1-x)A(x)MnO(3) (with divalent A) with small x is studied. We analyze an extension of the d ouble-exchange model using the Schwinger boson formalism. Earlier work by de Gennes on the existence of a canted phase is reproduced, althou gh this phase is shown to be unstable towards phase separation in a br oad regime of physical interest. We numerically solve the mean-field e quations for our model and exhibit its phase diagrams. [S0163-1829(98) 01238-7].