Orbitronic effect on the magnetic reconstruction of monocell SrMnO3 on ferroelectric BaTiO3 substrate

Abstract

The magnetic reconstruction of doped LaMnO3 on the ferroelectric substrate intrinsically involves sizeable carrier inhomogeneity on the scale of one-unit cell due to the charge screening effect at the interface. The small variation in Mn-d valence caused by the inhomogeneity may be responsible for the conflicting magnetic patterns predicted for thick magnetic films. To avoid the complexity resulting from the carrier inhomogeneity, we consider in this paper the magnetic reconstruction of a rigorously carrier homogeneous monocell SrMnO3 film on a BaTiO3 substrate. Stoichiometric SrMnO3 is used to further prevent the film from structural defects and associated Anderson's localization. Our study showed that magnetic reconstruction takes place between nearest-neighbor antiferromagnetic to ferromagnetic structures during polarization reversal of the substrate even if the ground state of bulk SrMnO3 is far away from the magnetic phase boundary. Furthermore, the estimated effective magnetoelectric coupling coefficient is 6.1 × 10−2 Oe cm V−1. It is more than doubled than those values obtained for thick magnetic films. Our detailed analysis suggested that the magnetic reconstruction is dictated by the modulated double-exchange ferromagnetic coupling mediated by Mn-d(eg)-orbitals against the superexchange antiferromagnetic coupling mediated by d(t2g)-orbitals. The nearest-chain antiferromagnetic structure also appears during the polarization reversal process.