title: Bulk magnetoelectricity in the hexagonal manganites and ferrites.
abstract: Improper ferroelectricity (trimerization) in the hexagonal manganites RMnO3 leads to a network of coupled structural and magnetic vortices that induce domain wall magnetoelectricity and magnetization (M), neither of which, however, occurs in the bulk. Here we combine first-principles calculations, group-theoretic techniques and microscopic spin models to show how the trimerization not only induces a polarization (P) but also a bulk M and bulk magnetoelectric (ME) effect. This results in the existence of a bulk linear ME vortex structure or a bulk ME coupling such that if P reverses so does M. To measure the predicted ME vortex, we suggest RMnO3 under large magnetic field. We suggest a family of materials, the hexagonal RFeO3 ferrites, also display the predicted phenomena in their ground state.
authors.affiliation: School of Applied and Engineering Physics, Cornell University, 224 Clark Hall, Ithaca, New York 14853, USA.
authors.forename: Hena
authors.initials: H
authors.lastname: Das
authors.affiliation: School of Applied and Engineering Physics, Cornell University, 224 Clark Hall, Ithaca, New York 14853, USA.
authors.forename: Aleksander L
authors.initials: AL
authors.lastname: Wysocki
authors.affiliation: Department of Physics and Astronomy and Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Geng
authors.affiliation: Department of Physics and Astronomy and Rutgers Center for Emergent Materials, Rutgers University, Piscataway, New Jersey 08854, USA.
authors.forename: Weida
authors.initials: W
authors.lastname: Wu
authors.affiliation: School of Applied and Engineering Physics, Cornell University, 224 Clark Hall, Ithaca, New York 14853, USA.
authors.forename: Craig J
authors.initials: CJ
authors.lastname: Fennie