Magnetization reversal in orthorhombic Sr-doped LaFeCrO.

In this paper we studied the reversal magnetization of La Sr FeCrO (x  =  0, 0.1 and 0.2) samples produced by combustion synthesis. The structural analysis was carried out by x-ray diffraction with Rietveld analysis. These analyses revealed that all samples have an orthorhombic structure with space group Pbnm (62) and that the Sr-doping induces a decrease of the lattice parameter. The x-ray photoelectron spectroscopy analysis indicates that the Sr-doping favor the change of the valence states of the Fe to Fe. The magnetization as a function of the temperature reveals an unusual magnetic behavior with a reversal of magnetization. The increase of the Sr content induces a decrease of the temperature where occurs an inversion of the magnetization and do the value of the magnetization at 5 K more negative. This effect is attributed to the increase of the concentration of Fe with increasing of the Sr content. The Fe and Cr with a valence of 4+  act as paramagnetic impurities in the antiferromagnetic lattice and are responsible for the changes in the magnetic behavior.