Route to tunable room temperature electric polarization in SrTiO ₃ –CoFe ₂ O ₄ heterostructures

Utilizing the magnetostrictive properties of CoFe₂O₄, we demonstrate reversible room temperature control of the Ti electronic structure in SrTiO₃-CoFe₂O₄ heterostructures, by inducing local and reversible strain in the SrTiO₃. By means of X-ray absorption spectroscopy, we have ascertained the changes that take place in the energy levels of the Ti 3d orbitals under the influence of an external magnetic field. The observed Ti electronic state when the sample is subjected to moderately large external magnetic fields and the disappearance of the induced phase upon their removal indicates lattice distortions that are suggestive of the development of a net electric polarization.