  The phase diagram of the double exchange model is studied in the large-S
limit at zero temperature in two and three dimensions. We find that the spiral
state has lower energy than the canted antiferromagnetic state in the region
between the antiferromagnetic phase and the ferromagnetic phase. At small
doping, the spiral phase is unstable against phase separation due to its
negative compressibility. When the Hund coupling is small, the system separates
into spiral regions and antiferromagnetic regions. When the Hund coupling is
large, the spiral phase disappears completely and the system separates into
ferromagnetic regions and antiferromagnetic regions.
