Interface magnetic and orbital reconstruction in an oxide multiferroic BiFeO$_{3}$/ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ heterostructure

Heteroepitaxial complex oxide heterostructures have attracted much scientific attention because of the novel phenomena and functionalities that have been observed to arise at interfaces as a consequence of the interplay between the spin, charge and orbital degrees of freedom. Here we are exploring a model heterointerface in which all the degrees of freedom, namely spin, charge, lattice, and orbital, are operative. The multiferroic perovskite, BiFeO$_{3}$ (BFO) is chosen as the model system that embodies the interplay between these degrees of freedom. This is counterposed across the interface with a highly correlated magnetic oxide, namely the doped manganite La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO). We have discovered the emergence of a novel magnetic state (1.4 $\mu _{B}$/Fe in the interface compared with only $\sim $0.02 $\mu _{B}$/Fe in bulk) in the BFO interface$_{ }$layer. This surprisingly large magnetization is associated with the emergence of spin and electronic orbital reconstruction at the heterointerface.