Titanium magnetic polarization at the Fe/BaTiO3 interfaces: An effect of ferroelectric polarization discontinuity

Abstract

The exotic magnetic phenomena and the associated functionalities have attracted extensive scientific interest in fundamental physics and cater to the purpose of the novel material search. In this article, with a combination of the electron energy-loss spectroscopy and the X-ray absorption spectroscopy, we have investigated the interfacial Fe atoms and the induced ferromagnetic moment of Ti atoms in Fe/BaTiO3 (BTO) heterostructures. The samples were grown with two different BTO thicknesses, thus resulting in two different states of distorted oxygen environments or different electrostatic potentials. We demonstrate that in these systems, the electronic and magnetic proximity effects remain coupled as the ferroelectric polar discontinuity is held responsible for an induced transfer of the interface electrons. These electrons migrate from the Fe2+ layers to the Ti(4+)–δ layers with the hybridization via O-2p oxide orbitals into Ti orbitals to screen the ferroelectric polarization. These findings, in charge neutral BaO–TiO2 and FeO layers or nonpolar/nopolar interface, essentially underline the central role of the covalent bonding in defining the spin-electronic properties.