Giant magnetoelectric effect in pure manganite-manganite heterostructures

Abstract

Obtaining strong magnetoelectric couplings in bulk materials and heterostructures is an ongoing challenge. We demonstrate that manganite heterostructures of the form $(\mathrm{Insulator})/(\mathrm{LaMn}{\mathrm{O}}_3{)}_{\mathrm{n}}/(\mathrm{CaMn}{\mathrm{O}}_3{)}_{\mathrm{n}}/(\mathrm{Insulator})$ show strong multiferroicity in magnetic manganites where ferroelectric polarization is realized by charges leaking from $\mathrm{LaMn}{\mathrm{O}}_3$ to $\mathrm{CaMn}{\mathrm{O}}_3$ due to repulsion. Here, an effective nearest-neighbor electron-electron (electron-hole) repulsion (attraction) is generated by cooperative electron-phonon interaction. Double exchange, when a particle virtually hops to its unoccupied neighboring site and back, produces magnetic polarons that polarize antiferromagnetic regions. Thus a striking giant magnetoelectric effect ensues when an external electrical field enhances the electron leakage across the interface.

This version supersedes arXiv:1203.3283