Enhancement of magnetoelectric coupling by insertion of Co atomic layer into Fe₃Si/BaTiO₃(001) interfaces identified by first-principles calculations

Magnetoelectric (ME) coupling of Ferromagnetic(FM)/ferroelectric(FE) interfaces is stronger than those of single phase multiferroic materials. Especially, interface ME effect caused by bonding effect between interfacial atoms has been reported in many FM/FE interfaces and observed at room temperature. In this study, we examine interface ME coupling at Fe₃Si/Co/BaTiO₃ heterostructures by using first-principles calculations based on density functional theory to clarify the influence of atomic-layer insertion on the ME effect. D0₃-type Fe₃Si has only 0.1 % lattice mismatch with tetragonal BaTiO₃ (001), and it is considered as promising to emerge the interfacial ME effect. We construct several interface structures and compare the energy of each structure. Comparing the Fe₃Si/BaTiO₃ interface with the Fe₃Si/Co/BaTiO₃ interface, it is found that the interface ME effect is greatly increased when Co is inserted. We also clarify the differences in ferroelectric displacement and magnetic properties between Fe₃Si/BaTiO₃ and Fe₃Si/Co/BaTiO₃.