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Synthesis and Characterization of BaTiO3/CoFe2O4 thin films Helen R. C. S. Andrade1 , Luciana M. Seara2, Nelcy D. S. Mohallem1,2* 1

Laboratory of Nanostructured Materials, DQ/UFMG, Belo Horizonte-MG, Brazil

2

Microscopy Centre, UFMG, Belo Horizonte-MG, Brazil

*[email protected] ABSTRACT Nanocomposites formed by ferrimagnetic and ferroelectric materials are multiferroic material in which magnetoelectric coupling occurs via piezoelectricity and magnetostriction phenomena. These nanocomposites have a variety of applications in tunable microwave devices using electric control of spin wave propagation or new magnetic memories in which the magnetic response is controlled by electric field. In this work, transparent and homogeneous thin films of barium titanate interleaved with cobalt ferrite were prepared by sol–gel method using dip-coating process. Films of pure barium titanate and cobalt ferrite were also prepared for comparison. The nanocomposite films were deposited onto clean quartz substrates, where a coating of each material was deposited interleaved, where the cobalt ferrite film formed the last layer. The films were dried in air after each dipping and heated at 900 oC for 1 hour to convert the amorphous films into crystalline ones. The samples were characterized by low angle X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) and UV-Vis spectroscopy. INTRODUCTION Nanocomposites thin films formed by ferrimagnetic and ferroelectric materials have been studied in the last years due to their important applications, such as tunable microwave devices using electric control of spin wave propagation, or new magnetic memories in which the magnetic response is controlled by electric field [1]. The magnetoelectric behaviour of these composites is dependent on their microstructure and of the coupling interaction across the ferromagnetic–ferroelectric interface [2]. These films can be formed by particles of one phase embedded into another phase, one phase surrounded by another phase or alternating layers of the two phases [3] Nanostructured films of BaTiO3/CoFe2O4, with ferrimagnetic and ferroelectric behavior, have been obtained by pulsed laser deposition [4]; by rf magnetron sputtering [5]; by laser molecular beam epitaxy [6] and by sol-gel process [7] to test their magnetoelectric characteristics. Sol-gel process has been an efficient method to produce this kind of thin film. Through this method, a good control of the sample morphology, texture, structure, and chemical composition can be attained by careful monitoring in the physical-chemistry parameters of the precursor solution and of the deposition process [8, 9].

In this work, we describe the preparation of nanocomposite thin films formed by thin films of barium titanate and cobalt ferrite interleaved, obtained by sol–gel process using the dipcoating technique. The morphological and structural evaluation of BaTiO3/CoFe2O4 thin films was made using atomic force microscopy (AFM), scanning electron microscopy (SEM) and Xray diff