Strain and electric field control of the orbital and spin order in multiferroic \(\hbox {BiMnO}_3\)

The new frontier for spintronics is the realization of devices in which the spin can be controlled by electric fields. Multiferroics, materials exhibiting strong interplay between spin and orbital degrees of freedom, are candidates for the realization of such a paradigm. In this work, we study the magnetoelectric coupling in epitaxial $$\hbox {BiMnO}_3$$ thin films which exhibit a large saturation magnetization. By combining X-ray absorption spectroscopy data and theoretical modeling, we demonstrate that $$\hbox {BiMnO}_3$$ thin films have an improper magnetoelectric behavior, characterized by competing antiferromagnetic and ferromagnetic correlations. As a consequence, we show that in these materials the Mn-3d orbital and magnetic orders can be tuned via the ferroelectric polarization, opening perspectives for the realization of novel spintronic devices.