Dynamic magnetoelectric effects in bulk and layered composites of cobalt zinc ferrite and lead zirconate titanate

Abstract

Low frequency magnetoelectric (ME) coupling has been investigated in bulk and multilayers of cobalt zinc ferrite, Co 1-x Zn x Fe 2 O 4 (x=0-0.6), and lead zirconate titanate. In bulk samples, the transverse and longitudinal couplings are weak and are of equal magnitude. A substantial strengthening of ME interactions is evident in layered structures, with the ME voltage coefficient a factor of 10-30 higher than in bulk samples. Important findings of the studies in layered composites are as follows. (i) The transverse coupling is stronger than the longitudinal coupling. (ii) The strength of ME interactions is dependent on Zn substitution with a maximum for x=0.4. (iii) Analysis of volume and static magnetic field dependence of ME voltage coefficients reveal a weak coupling at the ferromagnetic-piezoelectric interface. (iv) The interface coupling k increases with Zn substitution and k versus x profile shows a maximum centered at x=0.4. (iv) The Zn-assisted enhancement is attributed to efficient magneto-mechanical coupling in the ferrite.PACS IntroductionIn a magnetoelectric (ME) material, an applied magnetic field produces a dielectric polarization or an external electric field results in an induced magnetization [1]. The induced polarization P is related to the magnetic field H by P = α H, where α is the ME-susceptibility. For a single-phase material to be magnetoelectric, one requires a long-range magnetic order and the presence of permanent electric dipoles. The (static) effect, first observed in antiferromagnetic Cr 2 O 3, is weak in single-phase compounds [2]. But a composite of piezomagnetic-piezoelectric phases is also expected to be magnetoelectric since α = δP/δH is a "product-property" that results from magnetostriction induced deformation and piezoelectric charge generation [3][4][5]. We are interested in the dynamic ME effect; for an ac magnetic field δH applied to a biased composite, one measures the induced voltage δV. The ME voltage coefficient α′ E = δV/t′δH and is related to the ME susceptibility through α = ε o ε r α′ E where t′ is the composite thickness and ε r is the relative permittivity.This report is concerned with the synthesis of bulk and layered composites of ferromagneticferroelectric oxides and studies on the nature of magnetoelectric interactions. Composites of interest in the past were bulk samples of nickel ferrite or cobalt ferrite with BaTiO 3 or lead zirconate titanate (PZT) [ 3,4]. Powders of the two oxides are mixed

Magnetoelectric effect of mildly conducting magnetostrictive/piezoelectric particulate composites

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Mechanical, Magnetic, and Microstructural Characterization of Ni0.9Co0.1Fe2O4 Produced by the Ceramic Method

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Multiferroic Cobalt Ferrite-Lead Iron Tungstate Composites

“…Since single phase multiferroics are rare and show some disadvantages, like low electrical resistivity or low magnetic transition temperatures, ferroelectric-ferromagnetic composites are often used to attain strong magnetoelectric effect as a "product property" of the material. The most popular compositions are those containing cobalt or nickel ferrite as a ferromagnetic phase and piezoelectric BaTiO 3 or Pb(ZrTi)O 3 as a ferroelectric phase [1][2][3][4][5]. This paper focuses on the studies of microstructure, dielectric, magnetic and magnetoelectric properties of bulk composites based on ferrite CoFe 2 O 4 (CF) and solid state solution of relaxor ferroelectric Pb(Fe 2/3 W 1/3 )O 3 (PFW) and normal ferroelectric PbTiO 3 (PT).…”