Mechanism of Doping-Induced Orientation of Magnetic Phase in a Sol–Gel-Derived Ni_0.5Zn_0.5Fe₂O₄/BaTiO₃ Multiferroic Thin Film with High Magnetoelectric Coupling

Abstract

1−3-Type ferromagnetic/ferroelectric multiferroic composite thin films for high magnetoelectric coupling have been fabricated successfully on Si(111) substrate. The mechanism of control of the formation of (111)-oriented Ni 0.5 Zn 0.5 Fe 2 O 4 (NZFO) magnetic phases arrayed in and isolated by ferroelectric phases of BaTiO 3 (BTO) was explored in detail. By adjusting the Ti 4+ doping content in the NZFO phase and the composition of constituent phases to change the contact angle and heterogeneous nucleation barrier, the NZFO phase was controlled to grow with high crystallinity and dominantly in the (111) orientation. Under an NZFO composition content of 0.9, the contact angle of the film is minimum, ∼10°or less; the nucleation ability of NZFO is the best; the crystallinity is the maximum; and the orientation degree is 300.97. Taking the 1−3-type composite thin films into consideration, 0.9NZFO/0.1BTO composite thin films with nano-BTO filled possessed high to 44.8% sharp drop of the magnetic moment at 398−400 K, around the Curie temperature of BTO. It represented a giant magnetoelectric coupling response. It is interesting to understand the reason and to know how to fabricate multiferroic thin films with high magnetoelectric coupling.