Phase separation, low-field magnetic and transport properties of Pr0.75Na0.25Mn0.9Fe0.1O3

A single-phase perovskite Pr0.75Na0.25Mn0.9Fe0.1O3 was prepared by a sol–gel technique. Some magnetic properties, including magnetization, AC susceptibility and magnetotransport property at low temperatures, were investigated. The analysis of data shows that there exist correlated ferromagnetic clusters embedded in a charge-ordered (CO) antiferromagnetic insulative matrix. The growth of ferromagnetic clusters with increasing magnetic field was examined. The results indicate that the ferromagnetic clusters are far from filling up the whole sample, even up to H=5T. The sample maintains an insulating state at temperatures below ∼65 K for H⩽5 T, and the transport property is natural for magnetic semiconductors at temperatures above ∼65 K. The temperature dependence of resistivity for Pr0.75Na0.25Mn0.9Fe0.1O3 shows charge-ordering transition at ∼192 K. Single-phase Pr0.75Na0.25MnO3 was also prepared and studied in order to understand the effect of Fe doping. The ferromagnetism and conductivity have been consistently improved by 10% Fe doping at the expense of CO antiferromagnetism. These behaviors are interpreted in terms of geometric effects (size of the A-sites cations and of the dopant) and the Mn3+/Mn4+ ratio.