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Magnetization reversal in orthorhombic Sr-doped LaFe0.5Cr0.5O3-δ
P V Coutinho1, N O Moreno1, E A Ochoa1
1Departamento de Física, Universidade Federal de Sergipe, Rod. Marechal Rondon, s/n, 49100-000, São Cristóvão-SE, Brazil.
Abstract:
In this paper we studied the reversal magnetization of La1-x Sr x Fe0.5Cr0.5O3-δ (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 Fe3+ to Fe4+. 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 Fe4+ 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.
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