Magnetoelectric properties of three-layered composite thin film fabricated by pulsed laser deposition

Abstract

Magnetostriction-piezoelectric composite films present promising application prospects due to the presence of the magnetoelectric effect. In this paper, a sandwich structure Bi4Ti3O12/CoFe2O4/Bi4Ti3O12 composite film was prepared in a pulsed laser deposition system. The morphology, EDX, XPS, ferroelectric, piezoelectric, ferromagnetic and magnetoelectric properties were investigated in detail. In the sample, the atomic percentages of Bi, Ti and O elements measured by EDX are 35.373%, 12.824% and 46.578%, respectively. The out-of-plane electric domain structure and the in-plane magnetic domain structure show that BTO and CFO phases have excellent ferroelectricity (Pr = 1.57 μC/cm−2) and ferromagnetism (Mr = 104.83 emu/cc), respectively. The piezoelectric properties are proportional to the ferroelectric properties, so the composite thin films also have good piezoelectric properties (d33max = 192 p.m./v). Moreover, a great magnetoelectric coupling coefficient (∼11.95 mV/cm·Oe) was obtained by mechanical strain transfer and interface coupling. By adding a ferroelectric layer to the composite thin film, the clamping effect can be reduced and the coupling between the ferroelectric and the ferromagnetic layers can be increased, providing the experimental basis for the research of magnetoelectric coupling effect.