From Multiferroic Composite Oxides to Composite Thin Films Fabrication

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SUMMARYThe purpose of this research is to produce electronic sensors which in turn will help foster a new Canadian electronic industry based on multiferroics. Multiferroic materials, or multiferroics (MF), which include ceramic compounds and their thin films on an appropriate substrate, show both electronic and magnetic properties. We look for materials that show at least two ferroic behaviors such as ferromagnetism (permanent magnetic moment) and ferroelectricity (spontaneous electric polarization). There are several single-phase oxides that show multiferroic behaviors; however, these behaviors are not observed at room temperature, which is an important requirement for any application purposes such as memory devices that can be electrically written and magnetically read.New research on composite materials (material containing two or more compounds) indicates that one can create an environment where the magnetic phase in the composite affect electric phase in the composite and vise-versa; this is called the magnetoelectric effect (ME). Scientist have been focusing on ceramic composites of several compounds such as CoFe2O4-BaTiO3, Pb(ZrTi)O3 (PZT), Ferrite and BaTiO3 which show MF/Me effects both in ceramics and thin films on substrates.Currently these composite materials are formed by introducing magnetic particles or magnetic nanofibers into ferroelectric materials or creating two-phase layers by fabricating thin film of composites. We propose to fabricate core-shells where the core of the particle is made up of nanoparticles of magnetic materials and the shell (a thick layer on the surface of the core) is made up of ferroelectric materials. This process can be achieved by a wet chemical technique and by controlling the synthesizing factors. Using this method, we anticipate fabricating nanocomposite shapes and create a coherent interface between the two phases. We are planning to use these composite nanoparticles to fabricate high density ceramic tablets, essential for film fabrication, such as CoFe2O4/BiFeO3, La2/3Sr1/3MnO3/ Pb(ZrTi)O3 and new tetragonal tungsten Bronzes.We also continue our quest to find new single multiferroic material compounds. We are focusing on materials with a structure which is important for the observation of ferroelectricity. It should also contain elements with high magnetic moments (transition metal or rare earth) for observing ferromagnetism. Our plan is to produce the thin films of these compounds using pulse laser deposition or RF-sputtering techniques, to characterize their physical, electronic and magnetic properties in my lab, and to examine their possible applications. The ultimate outcome will be the production of electronic sensors using multiferroic materials (MF).