Correlation of High Magnetoelectric Coupling with Oxygen Vacancy Superstructure in Epitaxial Multiferroic BaTiO?-BiFeO? Composite Thin Films.

ABSTRACT: Epitaxial multiferroic BaTiO?-BiFeO? composite thin films exhibit a correlation between the magnetoelectric (ME) voltage coefficient ?_ME and the oxygen partial pressure during growth. The ME coefficient ?_ME reaches high values up to 43 V/(cm·Oe) at 300 K and at 0.25 mbar oxygen growth pressure. The temperature dependence of ?_ME of the composite films is opposite that of recently-reported BaTiO?-BiFeO? superlattices, indicating that strain-mediated ME coupling alone cannot explain its origin. Probably, charge-mediated ME coupling may play a role in the composite films. Furthermore, the chemically-homogeneous composite films show an oxygen vacancy superstructure, which arises from vacancy ordering on the {111} planes of the pseudocubic BaTiO?-type structure. This work contributes to the understanding of magnetoelectric coupling as a complex and sensitive interplay of chemical, structural and geometrical issues of the BaTiO?-BiFeO? composite system and, thus, paves the way to practical exploitation of magnetoelectric composites.

SUBMITTER: Lorenz M 

PROVIDER: S-EPMC5456545 | biostudies-literature | 2016 Jan

REPOSITORIES: biostudies-literature