First principles study of magnetoelectric coupling in Co2FeAl/BaTiO3 tunnel junctions

Abstract

Critical thickness for ferroelectricity and the magnetoelectric effect of Co₂FeAl/BaTiO₃ multiferroic tunnel junctions (MFTJs) are investigated using first-principles calculations. The ferroelectric polarization of the barriers can be maintained upto a critical thickness of 1.7 nm for both the Co₂/TiO₂ and FeAl/TiO₂ interfaces. The magnetoelectric effect is derived from the difference in the magnetic moments on interfacial atoms, which is sensitive to the reversal of electric polarization. The magnetoelectric coupling is found to be dependent on the interfacial electronic hybridizations. Compared with the Co₂/TiO₂ interface, more net magnetization change is achieved at the FeAl/TiO₂ interface. In addition, the in-plane strain effect shows that in-plane compressive strain can lead to the enhancement of ferroelectric polarization stability and intensity of magnetoelectric coupling. These findings suggest that Co₂FeAl/BaTiO₃ MFTJs could be utilized in the area of electrically controlled magnetism, especially the MFTJ with loaded in-plane compressive strain with the FeAl/TiO₂ interface.