title: Microscopic origin of large negative magnetoelectric coupling in Sr(1/2)Ba(1/2)MnO3.
abstract: With a combined ab initio density functional and model Hamiltonian approach we establish that in the recently discovered multiferroic phase of the manganite Sr(1/2)Ba(1/2)MnO3 the polar distortion of Mn and O ions is stabilized via enhanced in-plane Mn-O hybridizations. The magnetic superexchange interaction is very sensitive to the polar bond-bending distortion, and we find that this dependence directly causes a strong magnetoelectric coupling. This novel mechanism for multiferroicity is consistent with the experimentally observed reduced ferroelectric polarization upon the onset of magnetic ordering.
authors.affiliation: CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Trieste, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Giovannetti
authors.forename: Sanjeev
authors.initials: S
authors.lastname: Kumar
authors.forename: Carmine
authors.initials: C
authors.lastname: Ortix
authors.forename: Massimo
authors.initials: M
authors.lastname: Capone
authors.forename: Jeroen
authors.initials: J
authors.lastname: van den Brink