title: Competition of magneto-dipole, anisotropy and exchange interactions in composite multiferroics.
abstract: We study the competition of magneto-dipole, anisotropy and exchange interactions in composite three-dimensional multiferroics. Using Monte Carlo simulations we show that magneto-dipole interaction does not suppress the ferromagnetic state caused by the interaction of the ferroelectric matrix and magnetic subsystem. However, the presence of the magneto-dipole interaction influences the order-disorder transition: depending on the strength of magneto-dipole interaction the transition from the ferromagnetic to the superparamagnetic state is accompanied either by the creation of vortices or domains of opposite magnetization. An unusual temperature hysteresis loop occurs in composite multiferroics due to non-monotonic behavior of exchange interaction versus temperature. The origin of this hysteresis is related to the presence of stable magnetic domains which are robust against thermal fluctuations.
authors.affiliation: Institute for High Pressure Physics, Russian Academy of Science, Troitsk 142190, Russia. Department of Theoretical Physics, Moscow Institute of Physics and Technology, 141700 Moscow, Russia.
authors.forename: A M
authors.initials: AM
authors.lastname: Belemuk
authors.forename: O G
authors.initials: OG
authors.lastname: Udalov
authors.forename: N M
authors.initials: NM
authors.lastname: Chtchelkatchev
authors.forename: I S
authors.initials: IS
authors.lastname: Beloborodov