Fe-doping-induced charge-orbital ordering in manganese oxides

We investigated Fe-doping effects on a ferromagnetic metallic crystal, (La$_{0.7}$Pr$_{0.3}$)$_{0.65}$Ca$_{0.35}$MnO$_3$, which locates near the phase boundary to the charge-orbital ordered insulator. It was found that the competing charge-orbital ordering correlation is induced by substituting a small amount of Fe atoms for Mn ones. Such a tendency nicely contrasts with the impurity-induced ferromagnetic metallic phase appearing in the charge-orbital ordered manganites, for example, Cr-doped Nd$_{0.5}$Ca$_{0.5} $MnO$_3$ as intensively investigated for past years. Furthermore, we observed glassy magnetotransport properties as well as diffuse insulator-metal transition, such as magnetic- field annealing effects and long-time relaxation, like a ``relaxor ferromagnet".