Magnetoelectric coupling at the interface of BiFeO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ multilayers

Magnetoelectric coupling has recently been demonstrated in a system composed of the ferromagnetic manganite La$_{0.7}$Sr$_ {0.3}$MnO$_3$ (LSMO) and the ferroelectric antiferromagnetic BiFeO$_3$ (BFO) [1,2]. Using a realistic microscopic model we study the effects of the charge redistribution and orbital reconstruction on the LSMO/BFO interface ground state. We find that the BFO interface (ferro)magnetism is affected by the charge density at the interface which, in turn, can be modified by the ferroelectric polarization on BFO. This interface induced magnetoelectric coupling leads to the recently observed electric field controlled exchange bias.\\[4pt] [1] S. M. Wu et al, Nature Materials 9, 756 (2010).\\[0pt] [2] P. Yu et al, Phys. Rev. Lett. 105, 027201 (2010).