Magnetotransport properties of SrFeO2.95 perovskite

The resistivity, magnetoresistance, and Mössbauer effect of the metallic spiral antiferromagnet SrFeO2.95 were examined in the temperature range 4.5–300K. Two peaks were found in the plot of the temperature derivative of resistivity (dρ/dT) versus temperature. The temperature of the upper peak, TN, corresponding to the onset of antiferromagnetic order, decreases monotonically from 105 to 98K as the applied field increases from 0 to 9T. This is due to the reduced antiferromagnetic superexchange interaction, while the temperature of the second transition, Ta, which corresponds to a peak at low temperatures and coincides with the weak anomaly in χ(T) curve, remains constant upto 3.8T and shows a rapid increase in the range from 40 to 65K, as the magnetic field increases further. This is caused by the enhancement of the disappearance of Fe3+δ paramagnetic domains and also by the enhancement of the helical–conical spin transformation for the applied field greater than 3.8T.