Fe doping induced cluster/spin glass state and metamagnetic transition in phase separated La0.5Sr0.5Mn1-xFexO3

We report the impurity doping effects in manganites La0.5Sr0.5Mn1-xFexO3 (0 <= x <= 0.2) and the field-induced metamagnetic transition in which the antiferromagnetic insulating phase transforms into ferromagnetic metallic phase. The Rietveld refined results of XRD data display no obvious structure change with a significant degree of Fe3+ doping on Mn sites. Significant ferromagnetism suppression and magnetic inhomogeneity tendency upon Fe3+-doping are evidenced, phase separated and spin-glass like states are identified. With applying a pulsed high magnetic field up to 50 T, a metamagnetic transition was induced, especially clear for x >= 0.1 compounds, which exhibited an irreversible phase transition from antiferromagnetic to ferromagnetic phase, and a saturation magnetization was obtained. The replacement of Mn3+ by Fe3+ ions eliminates the effects of lattice structure change on the magnetic and electronic properties because of the very similar ionic size of Mn3+ and Fe3+, but reduces the Mn3+/Mn4+ ratio and depopulates the number of available hopping sites and the hopping electrons, thus weakens the double exchange interaction. The occurrence of the AFM superexchange interaction via Fe3+-O-2(-)-Fe3+ and Fe3+-O-2(-)-Mn3+ bonds may bring about the competition between the antiferromagnetic ordering and the ferromagnetic ordering, leading to a cluster/spin-glass behavior in the samples with high Fe dopants concentration.