  Ferroelectric control of interfacial magnetism has attracted much attention.
However, the coupling of these two functionalities has not been understood well
at the atomic scale. The lack of scientific progress is mainly due to the
limited characterization methods by which the interface's magnetic properties
can be probed at an atomic level. Here, we use polarized neutron reflectometry
(PNR) to probe the evolution of the magnetic moment at interfaces in
ferroelectric/strongly correlated oxide [PbZr0.2Ti0.8O3/La0.8Sr0.2MnO3
(PZT/LSMO)] heterostructures. We find that there is always suppressed
magnetization at the surface and interface of LSMO and such magnetic
deterioration can be strongly improved by interfacing with a strongly polar PZT
film. The magnetoelectric coupling of magnetism and ferroelectric polarization
occurs within a couple of nanometers of the interface as demonstrated by the
enhanced interfacial magnetization beyond the bulk value by 5% depending on the
polarization of PZT. The latter value is 70% higher than the surface
magnetization of a LSMO film without interfacing with a ferroelectric layer.
These compelling results not only probe the presence of nanoscale magnetic
suppression and its control by ferroelectrics, but also emphasize the
importance of utilizing probing techniques that can distinguish between bulk
and interfacial phenomena.
