Electric-field control of magnetic ordering in the tetragonal-like BiFeO ₃

We propose a way to use an electric field to control the magnetic ordering of the tetragonal-like BiFeO ₃. Based on systematic first-principles studies of the epitaxial strain effect on the ferroelectric and magnetic properties of the tetragonal-like BiFeO ₃, we find that there exists a transition from C-type to G-type antiferromagnetic (AFM) phase at the in-plane constant a∼ 3.91 when the ferroelectric polarization is along the [001] direction. Such magnetic phase transition can be explained by the competition between the Heisenberg exchange constants J _1c and J _2c under the influence of biaxial strain. Interestingly, when the in-plane lattice constant enlarges, the preferred ferroelectric polarization tends to be tilted and eventually lies in the plane (along the [110] direction). It is found that the orientation change of ferroelectric polarization, which can be realized by applying an external electric field, has significant impact on the Heisenberg exchange parameters and therefore the magnetic orderings of tetragonal-like BiFeO ₃. For example, at a∼ 3.87 , an electric field along the [111] direction with magnitude of 0.01 MV/cm could change the magnetic ordering from C-AFM to G-AFM. As the magnetic ordering affects many physical properties of the magnetic material, e.g., magnetoresistance, we expect that such strategy would provide a new avenue to the application of multiferroic materials. © Europhysics Letters Association.