title: Nanoparticle-Based Magnetoelectric BaTiO3-CoFe2O4Thin Film Heterostructures for Voltage Control of Magnetism.
abstract: Multiferroic composite materials combining ferroelectric and ferromagnetic order at room temperature have great potential for emerging applications such as four-state memories, magnetoelectric sensors, and microwave devices. In this paper, we report an effective and facile liquid phase deposition route to create multiferroic composite thin films involving the spin-coating of nanoparticle dispersions of BaTiO3, a well-known ferroelectric, and CoFe2O4, a highly magnetostrictive material. This approach offers great flexibility in terms of accessible film configurations (co-dispersed as well as layered films), thicknesses (from 100 nm to several μm) and composition (5-50 wt % CoFe2O4with respect to BaTiO3) to address various potential applications. A detailed structural characterization proves that BaTiO3and CoFe2O4remain phase-separated with clear interfaces on the nanoscale after heat treatment, while electrical and magnetic studies indicate the simultaneous presence of both ferroelectric and ferromagnetic order. Furthermore, coupling between these orders within the films is demonstrated with voltage control of the magnetism at ambient temperatures.
authors.affiliation: Laboratory for Multifunctional Materials, Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, 8093, Zurich, Switzerland.
authors.forename: Derya
authors.initials: D
authors.lastname: Erdem
authors.forename: Nicholas S
authors.initials: NS
authors.lastname: Bingham
authors.affiliation: Laboratory for Multifunctional Materials, Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, 8093, Zurich, Switzerland.
authors.forename: Florian J
authors.initials: FJ
authors.lastname: Heiligtag
authors.forename: Nicolas
authors.initials: N
authors.lastname: Pilet
authors.forename: Peter
authors.initials: P
authors.lastname: Warnicke
authors.forename: Carlos A F
authors.initials: CA
authors.lastname: Vaz
authors.forename: Yanuo
authors.initials: Y
authors.lastname: Shi
authors.forename: Michele
authors.initials: M
authors.lastname: Buzzi
authors.forename: Jennifer L M
authors.initials: JL
authors.lastname: Rupp
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Heyderman
authors.affiliation: Laboratory for Multifunctional Materials, Department of Materials, ETH Zurich , Vladimir-Prelog-Weg 5, 8093, Zurich, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Niederberger
keywords: X-ray magnetic circular dichroism; barium titanate; cobalt ferrite; multiferroic composites; nanoparticles; thin films