Dielectric, piezoelectric and magnetic behavior of CoFe2O4/BNT–BT0.08 monolayer thin films composites

• BNT-BT 0.08 /CoFe 2 O 4 composite thin films monolayer with different molar ratios were prepared. • These thin films showed good dielectric, piezoelectric and magnetic properties. • These macroscopic properties depend on the BNT-BT 0.08 /CoFe 2 O 4 molar ratio. We report in this paper on the monolayer composites thin films that have the magnetic spinel CoFe 2 O 4 and the piezoelectric perovskite BNT-BT 0.08 as constituent phases. Composite thin films of CoFe 2 O 4 and BNT-BT 0.08 , with molar ratios of 0.5:1, 1:1 and 1.5:1, have been deposited by spin coating method from a sol precursor, mixture type, of CoFe 2 O 4 and BNT-BT 0.08 . The monolayer thin films, deposited on Si/SiO 2 /TiO 2 /Pt substrate, were characterized using selected methods, such as: X-ray diffraction, scanning electron microscopy, atomic force microscopy/piezoelectric force microscopy, dielectric spectroscopy, and vibrating sample magnetometer. X-ray diffraction demonstrated the two phases: cubic CoFe 2 O 4 and rhombohedral BNT-BT 0.08 . Furthermore, the Si/SiO 2 /TiO 2 /Pt/BNT-BT 0.08 /CoFe 2 O 4 monolayers show a simultaneous enhancement of both the magnetization and coercivity with the increase of the magnetic phase, accompanied by a decrease of the dielectric constant. The obtained results reveal that the investigated monolayer structures present superior properties compared to those of bilayer composites.