Phase diagrams of perovskite-type manganese oxides

In this paper, a competition between a ferromagnetic metal and a charge/orbital-ordered insulator has been investigated for RE1−xAExMnO3 (x=0.45x=0.45) with RE and AE being rare earth elements, ranging from La to Gd, and alkaline earth elements, Ca, Sr and Ba, respectively. A phase diagram is deduced in the plane of the effective one-electron bandwidth versus the magnitude of quenched disorder, which can be controlled by the averaged value and the variance of the RE/AE ionic radii, respectively. In the vicinity of the phase boundary, the ferromagnetic transition temperature is critically suppressed, and the colossal magnetoresistance (CMR) is enhanced.