Magnetic interaction at an interface between manganite and other transition metal oxides

A general consideration is presented for the magnetic interaction at an interface between a perovskite manganite and other transition metal oxides. The latter is specified by the electron number n in the d_3z2-r2 level as (d_3z2-r2)ⁿ. Based on the molecular orbitals formed at the interface and the generalized Hund's rule, the sign of the magnetic interaction is rather uniquely determined. The exception is when the d_3z2-r2 orbital is stabilized in the interfacial manganite layer neighboring to a (d_3z2-r2)¹ or (d_3z2-r2)² system. In this case, the magnetic interaction is sensitive to the occupancy of the Mn d_3z2-r2 orbital. It is also shown that the magnetic interaction between the interfacial Mn layer and the bulk region can be changed. Manganite-based heterostructures thus show a rich magnetic behavior. We also present how to generalize the argument including t2g orbitals.