Magnetic spin structure and magnetoelectric coupling in BiFeO3-BaTiO3 multilayer

Magnetic spin structures in epitaxial BiFeO3 single layer and an epitaxial BaTiO3/BiFeO3 multilayer thin film have been studied by means of nuclear resonant scattering of synchrotron radiation. We demonstrate a spin reorientation in the 15 × [BaTiO3/BiFeO3] multilayer compared to the single BiFeO3 thin film. Whereas in the BiFeO3 film, the net magnetic moment m→ lies in the (1–10) plane, identical to the bulk, m→ in the multilayer points to different polar and azimuthal directions. This spin reorientation indicates that strain and interfaces play a significant role in tuning the magnetic spin order. Furthermore, large difference in the magnetic field dependence of the magnetoelectric coefficient observed between the BiFeO3 single layer and multilayer can be associated with this magnetic spin reorientation.