  An oxide heterostructure made of manganite bilayers and ferroelectric
perovskites is predicted to lead to the full control of magnetism when
switching the ferroelectric polarizations. By using asymmetric polar interfaces
in the superlattices, more electrons occupy the Mn layer at the $n$-type
interface side than at the $p$-type side. This charge disproportionation can be
enhanced or suppressed by the ferroelectric polarization. Quantum model and
density functional theory calculations reach the same conclusion: a
ferromagnetic-ferrimagnetic phase transition with maximal change $>90%$ of the
total magnetization can be achieved by switching the polarization's direction.
This function is robust and provides full control of the magnetization's
magnitude, not only its direction, via electrical methods.
