Magnetotransport properties of SrFeO2.95 perovskite

The resistivity, magnetoresistance, and Mossbauer effect of the metallic sp iral antiferromagnet SrFeO2.95 were examined in the temperature range 4.5-3 00 K. Two peaks were found in the plot of the temperature derivative of res istivity (d rho /dT) versus temperature. The temperature of the upper peak, TN, corresponding to the onset of antiferromagnetic order, decreases monot onically from 105 to 98 K as the applied field increases from 0 to 9 T. Thi s is due to the reduced antiferromagnetic superexchange interaction, while the temperature of the second transition, T-a, which corresponds to a peak at low temperatures and coincides with the weak anomaly in X(T) curve, rema ins constant upto 3.8 T and shows a rapid increase in the range from 40 to 65 K, as the magnetic field increases further. This is caused by the enhanc ement of the disappearance of Fe3+5 paramagnetic domains and also by the en hancement of the helical-conical spin transformation for the applied field greater than 3.8 T. (C) 2001 Published by Elsevier Science Ltd.