Magnetoelectric Coupling in Room Temperature Multiferroic Ba₂EuFeNb₄O₁₅/BaFe₁₂O₁₉ Epitaxial Heterostructures Grown by Laser Ablation

Multiferroic thin films are a promising class of multifunctional materials, since they allow the integration of multiple functionalities within a single device. In order to overcome the scarcity of single phase multiferroics, it is crucial to develop novel multiferroic heterostructures, combining good ferroelectric and ferromagnetic properties as well as a strong coupling between them. For this purpose, Ba₂EuFeNb₄O₁₅/BaFe₁₂O₁₉ multiferroic magnetoelectric bilayers have been epitaxially grown on niobium doped SrTiO₃ (100) single crystal substrates by pulsed laser deposition. The simultaneous presence of both ferroelectric and magnetic properties-due, respectively, to the Ba₂EuFeNb₄O₁₅ and BaFe₁₂O₁₉ components-was demonstrated at room temperature, attesting the multiferroic nature of the heterostructure. More interestingly, a strong magnetoelectric coupling was demonstrated (i) by manipulating the ferroelectric properties via an external magnetic field, and conversely, (ii) by tuning the magnetic properties via an external electric field. This strong magnetoelectric coupling shows the high interdependence of both ferroic orders in the Ba₂EuFeNb₄O₁₅/BaFe₁₂O₁₉ heterostructure, mediated by elastic (epitaxial) strain at the interfaces.