Fe-doping-induced evolution of charge-orbital ordering in a bicritical-state manganite

Abstract

Impurity effects on the stability of a ferromagnetic-metallic state in a bicritical-state manganite, ${({\mathrm{La}}_{0.7}{\mathrm{Pr}}_{0.3})}_{0.65}{\mathrm{Ca}}_{0.35}\mathrm{Mn}{\mathrm{O}}_{3}$, on the verge of metal-insulator transition have been investigated by substituting a variety of transition-metal atoms for Mn ones. Among them, Fe doping exhibits the exceptional ability to dramatically decrease the ferromagnetic transition temperature. Systematic studies on the magnetotransport properties and x-ray diffraction for the Fe-doped crystals have revealed that charge-orbital ordering evolves down to low temperatures, which strongly suppresses the ferromagnetic-metallic state. The observed glassy magnetic and transport properties as well as diffuse phase transition can be attributed to the phase-separated state where short-range charge-orbital-ordered clusters are embedded in the ferromagnetic-metallic matrix. Such a behavior in the Fe-doped manganites form a marked contrast to the Cr-doping effects on charge-orbital-ordered manganites known as the impurity-induced collapse of charge-orbital ordering.