Magnetic transitions and butterfly-shaped hysteresis of Sm-Fe-Al-based perovskite-type orthoferrite

Al doped SmFeO3 (SmFe1-xAlxO3; 0.0 <= x <= 0.15; step 0.05) were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing Al substitution in orthoferrite. The effective magnetic moment (mu(eff)) and the Curie constant (C) were calculated from the reciprocal of the molar magnetic susceptibility chi(-1)) versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, Neel temperature (T-N) and spin reorientation (T-SR) transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample; H-c=6198.8 Oe. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spintonic applications.