  Controlling magnetism by using electric fields is a goal of research towards
novel spintronic devices and future nano-electronics. For this reason,
multiferroic heterostructures attract much interest. Here we provide
experimental evidence, and supporting DFT analysis, of a transition in
La0.65Sr0.35MnO3 (LSMO) thin film to a stable ferromagnetic phase, that is
induced by the structural and strain properties of the ferroelectric BaTiO3
(BTO) substrate, which can be modified by applying external electric fields.
X-ray Magnetic Circular Dichroism (XMCD) measurements on Mn L edges with a
synchrotron radiation show, in fact two magnetic transitions as a function of
temperature that correspond to structural changes of the BTO substrate. We also
show that ferromagnetism, absent in the pristine condition at room temperature,
can be established by electrically switching the BTO ferroelectric domains in
the out-of-plane direction. The present results confirm that electrically
induced strain can be exploited to control magnetism in multiferroic oxide
heterostructures.
