Nonmonotonic variation of magnetization in Bi0.8La 0.2-xPbxFeO3 (0≤x≤0.2) multiferroics

Systematic studies of crystalline structure, magnetic and ferroelectric properties have been performed on polycrystalline Bi0.8La0.2−xPbxFeO3 ceramic samples, in which x changes continuously from 0 to 0.2. Rietveld refinement of the x-ray diffraction (XRD) patterns shows that the compound crystal structure changes gradually from pseudotetragonal to pseudocubic with increasing Pb concentration. Coupled with the structural and compositional changes, magnetic ordering of the samples exhibits significantly non-monotonical variation corresponding to x. The compound remnant magnetization (Mr) and coercivity (Hc) both reach minimum values close to zero at x=0.07. This variation of magnetic property in co-doped samples can be attributed to the extent of suppression of cycloid spin structure in original BiFeO3 with changing x. Unlike magnetic responses, the ferroelectric measurements show that the compounds have monotonical change in the remnant electric dipole polarization (Pr).