Influence of phase separation on the low-field magnetic properties of La1−xSrxMn1−yFeyO3

The magnetic properties of ceramic La1−xSrxMn1−yFeyO3 samples with x = 0.3 and y = 0.15−0.25 are investigated in magnetic fields of B = 10−103 G at a temperature T between 5−310 K. A ferromagnetic transition at TC, decreasing considerably with y, is accompanied with strong magnetic irreversibility at B = 10 G. The critical behavior of χ (T) ~ (T/TC − 1)−γ is governed at y = 0.15−0.20 by the percolative (γ ≈ 1.8) and Heisenberg (γ ≈ 1.4) spin systems.