To maximize the formation of an anisotropic interface between the magnetostrictive phase and the electrostrictive phase, a eutectic BaTiO3-CoFe2O4 multiferroic material is fabricated by containerless processing. The composites in this process had a fine eutectic structure, especially at a eutectic composition of BaTiO3:CoFe2O4 = 62:38. TEM observations revealed that the (1 0 0) plane of tetragonal BaTiO3 and the (1 0 0) plane of CoFe2O4 were oriented in parallel. In addition to the largest magnetodielectric effect in the eutectic-composition samples, we confirmed the permittivity is controlled linearly by applying a high magnetic field through forced magnetostriction. So far, the peak of the magnetodielectric effect around 0.25 T has been only found in the sintered CoFe2O4 polycrystalline sample. Thus, the containerless processing provides us a route to produce an ideal microstructure without accompanying 90° domain wall process and rotational magnetization process, which enhances the magnetodielectric effect.
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