02. Formation of charge ordering and complex magnetic properties in the (Bi, Ca) Mn1-xCrxO3

In this paper, two series samples, (Bi-rich, ), and (Bi-poor, ) are investigated by means of resistivity, magnetization and electron–spin–resonance. The formation process of charge ordering is studied. The evolution of charge ordering with Cr content is drastically different between Bi-rich and Bi-poor samples. Charge ordering “melts” gradually with increasing Cr content in Bi-rich system while “collapses” when in Bi-poor series. These results are understood by considering the evolution of the Mn3+/Mn4+ ratio with Cr doping in different systems. Complex magnetic properties are observed in Bi-poor series with the doping level increasing from zero to 0.24. These behaviors are discussed in the context of phase separation scenario.