The binary and ternary solid solutions, BiFeO3–BaTiO3, BiFeO3–ReFeO3–BaTiO3 (Re=Dy,Pr,La), and BiFeO3–BaFeO2.5–BaTiO3 have been explored for attaining ferromagnetic ferroelectrics in bulk ceramics and understanding the effect of rare earth orthoferrites ReFeO3 on the spontaneous magnetization. The coexistence of ferromagnetism and ferroelectricity has been observed over the composition range of 0.2⩽x⩽0.4 in the (1−x)BiFeO3–xBaTiO3 at room temperature. The introduction of DyFeO3 and LaFeO3 expands the composition range of the coexistence. The most superior ferromagnetic ferroelectrics obtained in this study are the 0.65BiFeO3–0.025DyFeO3–0.325BaTiO3 (Pr=5 μC/cm2,Mr=0.1 emu/g), 0.4875BiFeO3–0.025DyFeO3–0.4875BaTiO3 (Pr=7 μC/cm2,Mr=0.06 emu/g), and 0.475BiFeO3–0.05LaFeO3–0.475BaTiO3 (Pr=3.2 μC/cm2,Mr=0.2 emu/g). The spontaneous magnetization strongly depends on both the type and amount of the substitution components, DyFeO3, LaFeO3, PrFeO3, and BaFeO2.5 rather than the degree of G-type antiferromagnetic ordering. The origin of the spontaneous magnetization has been discussed in terms of antiferromagnetic ordering and charge carrier mediation.

Amorphous Y-Fe-O ferrite thin-films were deposited on GGG (111) substrates using reactive RF magnetron sputtering with a Y 2.84 Fe 5.16 O 12 ferrite sintered target. After that, the thin-films were post-annealed in air at temperatures higher than 650 degrees Celsius for 3 hours to be crystallized. In the XRD diagrams, large diffraction peaks from only YIG ferrite (444) or (888) plane were observed in the samples postannealed at over 1050 degrees Celsius. The half value width (∆θ 50 ) in the rocking curve for YIG ferrite (888) was as small as 0.13 degrees. These results proved that the YIG ferrite films have been grown in hetero-epitaxial manner on GGG (111) substrate with high orientation. The YIG ferrite thin-films had reasonable saturation magnetization of 1.7 kG, relatively low coercivity of less than 5 Oe and small ∆H of around 70 Oe. The YIG ferrite thin-films are useful for microwave magnetic devices.

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