Multiferroic properties of Bi3.15Nd0.85Ti3O12–CoFe2O4 bilayer films derived by a sol–gel processing

Multiferroic Bi3.15Nd0.85Ti3O12 (BNT)–CoFe2O4 (CFO) bilayer films with different preferential orientations and thickness fractions for the BNT layer were prepared on Pt/Ti/SiO2/Si substrate by a sol–gel processing. The experimental results showed that the bilayer films with preferentially a-axis oriented and thicker BNT layer have better ferroelectric properties. The magnetoelectric coupling response is weak when the degree of a-axis orientation of the BNT layer is low or the leakage current is high, while it is mainly controlled by the thickness fraction in other cases.

Research highlights
► Lead-free Bi3.15Nd0.85Ti3O12 (BNT)–CoFe2O4 (CFO) magnetoelectric (ME) bilayer films.
► Dependence of the ME response on thickness fraction and orientation of the BNT layer.
► The ME response is weak if the degree of a-axis orientation of the BNT layer is low.
► The strong ME response is controlled by the thickness fraction of the BNT layer.