Skip to Main content Skip to Navigation

Couplages magnéto-électriques dans le système multiferroïque artificiel : BaTiO₃ / CoFe₂O₄

Abstract : Magnetoelectric multiferroics are of particular interest in the field of spintronics, especially for the possible control of the magnetization using an electric field. The lack of intrinsic multiferroics can be circumvented by using artificial multiferroics, made with individual ferroelectric and magnetic phases. Although they may exhibit higher coupling values, the precise coupling mechanisms involved are still not well understood. Getting insights in the understanding of these phenomena requires studying well mastered and crystallized samples. The combination of BaTiO₃ thin films (3 to 20nm), the prototypical ferroelectric, and of CoFe₂O₄ ones, a highly magnetostrictive ferromagnet with a high Curie temperature, constitutes a suitable model system well suited for such a study. In this thesis, we realized CoFe₂O₄ / BaTiO₃ thin films of high crystalline quality by oxygen plasma assisted molecular beam epitaxy on a SrTiO₃ (001) substrates. First, we study independently for each phase the individual properties of chemistry, structure, magnetism and ferroelectricity, using in particular a range of synchrotron techniques. Based on those fundamental results, we set up direct and indirect magnetoelectric coupling experiments, where we apply an electric polarization to measure a change in magnetization, and vice versa. We manage to observe the magnetoelectric coupling, mainly through the strong interaction of the CoFe₂O₄ and BaTiO₃ films. The indirect mechanisms dominate however and involve structural as well as chemical modifications through ion displacement. Those ion displacements create reversible changes in resistance at room temperature. These results imply that, in addition to the evidenced multiferroic properties, the system makes also promise for resistive RAM devices applications.
Complete list of metadata

Cited literature [56 references]  Display  Hide  Download
Contributor : Abes Star :  Contact
Submitted on : Saturday, November 5, 2016 - 11:42:06 AM
Last modification on : Friday, July 2, 2021 - 3:46:03 AM
Long-term archiving on: : Monday, February 6, 2017 - 12:51:44 PM


Version validated by the jury (STAR)


  • HAL Id : tel-01392953, version 1


Thomas Aghavnian. Couplages magnéto-électriques dans le système multiferroïque artificiel : BaTiO₃ / CoFe₂O₄. Science des matériaux [cond-mat.mtrl-sci]. Université Paris-Saclay, 2016. Français. ⟨NNT : 2016SACLS310⟩. ⟨tel-01392953⟩



Record views


Files downloads