Magnetic phase diagram of layered manganites in the highly doped regime

The naturally layered colossal magnetoresistive manganites La2−2xSr1+2xMn2O7 exhibit an extremely varied range of magnetic and electronic behavior over a very narrow composition range between x=0.3 and x=0.5. The successful synthesis in our laboratories of compounds with nominally greater than 50%Mn4+ concentration has now allowed the study of this region of the phase diagram. Here we present detailed neutron diffraction measurements of these compounds with doping levels 0.5