The rombohedral BiFeO3 perovskite is a multiferroic compound that exhibits simultaneously ferroelectricity and antiferromagnetism, the last turning into ferromagnetism in thin film form. In addition, it has a very large spontaneous polarization. However, attaining single BiFeO3 phase materials with appropriate electrical properties and ferroelectric switching at room temperature is difficult because of the easy formation of secondary non-ferroelectric phases during the processing of the materials. The solid solutions of the BiFeO3 with other ABO3 perovskites show phase stability and good electrical properties. Among these solid solutions, the (1-x)BiFeO3-xPbTiO3 perovskites have an improved structural stability and an enhancement of the ferroelectricity/piezoelectricity in the proximity of the morphotrophic phase boundary (MPB), where the tetragonal and rombohedral phases, associated to PbTiO3 and BiFeO3, respectively, coexist. Today, key applications are envisaged for MPB BiFeO3-PbTiO3 perovskite materials in thin film form, since they fulfil many of the requirements demanded for applications (e.g., sensors, spintronics or data storage).  
The previous study of the crystal structure and of the ferroelectric properties has allowed us to determine that the MPB of this solid solution in films is close to the 0.65BiFeO3-0.35PbTiO3 composition. Therefore, we have devised in this work the deposition of MPB BiFeO3-PbTiO3 thin films on ferromagnetic Ni substrates. ~250 nm thick films were prepared by low-cost solution deposition methods and low-thermal treatments on Ni substrates with different thickness (from 1.7 mm thick to Ni foils). These substrates were coated with thin layers of Pt to avoid diffusion of Ni towards the film and to minimize the formation of NiOx interfaces. These 0.65BiFeO3-0.35PbTiO3 films on Pt-coated Ni substrates show appropriate electrical and ferroelectric properties. These properties together with the study of the magnetoelectric response of these MPB BiFeO3-PbTiO3 – Ni composite film materials is discussed here in comparison with results previously reported in the literature.

This work is part of the Spanish Project PID2019-104732RB-I00 and TED2021-130871B-C21 funded by MCIN/AEI/10.13039/501100011033. A.B. acknowledges the financial support of the Program INVESTIGO of the CAM, 09-PIN1-00004.3/2022.