Correlation of High Magnetoelectric Coupling with Oxygen Vacancy Superstructure in Epitaxial Multiferroic BaTiO3-BiFeO3 Composite Thin Films

Materials

Michael Lorenz³  Gerald Wagner¹  Vera Lazenka⁴  Peter Schwinkendorf³  Michael Bonholzer³  Margriet J. Van Bael²  André Vantomme⁴  Kristiaan Temst⁴  Oliver Oeckler¹  Marius Grundmann³ 

[1]Institut für Mineralogie, Kristallographie und Materialwissenschaft, Universität Leipzig, Leipzig D-04103, Germany

[2]Laboratorium voor Vaste-Stoffysica en Magnetisme, KU Leuven, Leuven B-3001, Belgium

[3]Institut für Experimentelle Physik II, Universität Leipzig, Leipzig D-04103, Germany

[4]Instituut voor Kern- en Stralingsfysica, KU Leuven, Leuven B-3001, Belgium

关键词: oxide thin films;    multiferroic composites;    magnetoelectric coupling;    magnetoelectric voltage coefficient;    oxygen vacancy superstructure;    pulsed laser deposition;   

DOI  :  10.3390/ma9010044

来源: mdpi

【 摘 要 】

Epitaxial multiferroic BaTiO₃-BiFeO₃ composite thin films exhibit a correlation between the magnetoelectric (ME) voltage coefficient α_ME and the oxygen partial pressure during growth. The ME coefficient α_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 α_ME of the composite films is opposite that of recently-reported BaTiO₃-BiFeO₃ 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 BaTiO₃-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 BaTiO₃-BiFeO₃ composite system and, thus, paves the way to practical exploitation of magnetoelectric composites.

【 授权许可】

CC BY   
© 2016 by the authors; licensee MDPI, Basel, Switzerland.