  Novel phenomena appear when two different oxide materials are combined
together to form an interface. For example, at the interface of LaAlO3/SrTiO3,
two dimensional conductive states form to avoid the polar discontinuity and
magnetic properties are found at such interface. In this work, we propose a new
type of interface between two nonmagnetic and nonpolar oxides that could host a
conductive state with magnetic properties, where it is the ferroelectric
polarization discontinuity instead of the polar discontinuity that leads to the
charge transfer, forming the interfacial conductive or magnetic states. As a
concrete example, we investigate by first-principles calculations the
heterostructures made of ferroelectric perovskite oxide PbTiO3 and
non-ferroelectric polarized oxides TiO2. We show that charge is transferred to
the interfacial layer forming an interfacial conductive state with
ferromagnetic ordering that may persist up to room temperature. Especially, the
strong coupling between bulk ferroelectric polarization and interface
ferromagnetism represents a new type of magnetoelectric effect, which provides
an ideal platform for exploring the intriguing interfacial multiferroics. The
findings here are important not only for fundamental science but also for
promising applications in nanoscale electronics and spintronics.
