Manipulating magnetoelectric energy landscape in multiferroics

Magnetoelectric coupling at room temperature in multiferroic materials, such as BiFeO(3), is one of the leading candidates to develop low-power spintronics and emerging memory technologies. Although extensive research activity has been devoted recently to exploring the physical properties, especially focusing on ferroelectricity and antiferromagnetism in chemically modified BiFeO(3), a concrete understanding of the magnetoelectric coupling is yet to be fulfilled. We have discovered that La substitutions at the Bi-site lead to a progressive increase in the degeneracy of the potential energy landscape of the BiFeO(3) system exemplified by a rotation of the polar axis away from the 〈111〉(pc) towards the 〈112〉(pc) discretion. This is accompanied by corresponding rotation of the antiferromagnetic axis as well, thus maintaining the right-handed vectorial relationship between ferroelectric polarization, antiferromagnetic vector and the Dzyaloshinskii-Moriya vector. As a consequence, La-BiFeO(3) films exhibit a magnetoelectric coupling that is distinctly different from the undoped BiFeO(3) films.