Effects of B-Site Disorder in Sr₂FeMoO₆ with Double Perovskite Structure

Abstract

Heat treatment effects on the physical properties have been investigated for Sr 2 FeMoO 6 single crystals with double perovskite structure. We have evaluated the occupancy g of the Fe 3+ ion on one sublattice of the perovskite- B site by Rietveld refinement of the synchrotron-radiation X-ray powder patterns. Both the saturation magnetization M s and critical temperature T c for the ferrimagnetic transition decrease linearly with g in the large- g region ( g ≥∼ 0.84), but begin to deviate from the empirical relations for g ≤∼ 0.84. We interpreted this behavior in terms of variation of the correlation length of the spin ordering.