Structure and magnetic properties of La0.7Sr0.3MnO3(1 - x)-SrFe12O19(x) composites

Magnetic soft-hard composites of perovskite La-Sr manganite (LSMO) and M-type Sr-hexaferrite (SrM), LSMO(1 - x)-SrM(x) with x = 0, 0.05, 0.1, 0.3, 0.5, and 1.0 were prepared by solid-state reaction. Although the two phases coexist without forming secondary phases, the saturation magnetization (M_S) value of the LSMO phase decreased with the doping of SrM (x ≥ 0.05). Clear double hysteresis behaviors were observed in the samples with x = 0.3 and 0.5, while single soft magnetic hysteresis was noted in the samples with x ≤ 0.1. In the M-T measurement, the composite with x = 0.5 exhibited a diffusive temperature dependence of magnetization unlike that of non-doped LSMO (x = 0). Weakening of ferromagnetism in the composites can be attributed to interatomic diffusion between the two phases occurring during calcination at 1200 °C.