Large magnetoresistance in SrFeO2.95

A large magnetoresistance effect in a Fe-based perovskite has been observed. A typical magnetoresistance (MR) is 15.5% for SrFeO2.95 at 5 K, and also a high field induced MR is noted at a temperature well above the antiferromagnetic transition temperature. Magnetization and transport measurements show that two transitions occur at temperatures around 107 and 65 K, respectively. The upper transition appears to correspond to the antiferromagnetic transition. The second transition, at low temperature, shows a resistivity minimum which coincides with the weak anomaly in the χ(T) curve. The upturn in ρ below 65 K arises from a T1/2 dependence of the conductivity. This upturn in ρ at low temperatures is a manifestation of electron–electron interaction and quantum interference effects in electronic conduction, such as weak localization in this helical magnetic system.