title: Ferromagnetism and orbital order in a topological ferroelectric.
abstract: We explore via density functional calculations the magnetic doping of a topological ferroelectric as an unconventional route to multiferroicity. Vanadium doping of the layered perovskite La(2)Ti(2)O(7) largely preserves electric polarization and produces robust ferromagnetic order and, hence, proper multiferroicity. The marked tendency of dopants to cluster into chains results in an insulating character at generic doping. Ferromagnetism stems from the symmetry breaking of the multiorbital V system via an unusual "antiferro"-orbital order, and from the host's low-symmetry layered structure.
authors.affiliation: CNR-IOM, UOS Cagliari, and Department of Physics, University of Cagliari, Cittadella Universitaria, Cagliari, I-09042 Monserrato, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Scarrozza
authors.forename: Alessio
authors.initials: A
authors.lastname: Filippetti
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Fiorentini