Elaboration et étude d'un système hybride "Oxyde ferrimagnétique / Métal non magnétique / Oxyde ferrimagnétique"

Abstract : This work is a contribution to the active research on new magnetic and electric properties of artificial heterostructures. “Ferrimagnetic oxide / Non magnetic metal / Ferrimagnetic oxide” systems have been deposited. In these systems, electrons are confined in the 2D metal layer and many electron reflections occur at the “metal / magnetic insulator”. Two different magnetisation alignments of the magnetic oxides (parallel and antiparallel) are required to obtain suitable magnetic properties, i.e. giant magnetoresistance (GMR). The growth control and the flatness of the different layers are needed to deposit epitaxial layers, in which electron scattering at grain boundaries is limited. Films are deposited by sputtering in a UHV chamber, structural studies have been made using mainly transmission electron microscopy and X-ray diffraction.
An epitaxial growth of single Fe3O4 and CoFe2O4 films has been obtained on Al2O3(0001) with a [111] growth axis and on MgO(001) with a [001] growth axis. We have also studied magnetic properties (exchange anisotropy) of epitaxial Fe3O4(x nm)/NiO(66 nm) bilayers , x varying from 5nm to 50nm, grown along a [111] and a [001] axis. Non oxydable metal growth (Pt, Au and Ag) on (001) and (111) Fe3O4 crystals has also been investigated.
We have achieved epitaxial growth of Fe3O4/M(M=Au,Pt)/CoFe2O4 layers on Al2O3(0001) with flat interfaces and suitable magnetic properties. Electric investigations have shown that the electrons are confined in the metallic layer. We have measured a 1.8% GMR ratio at 10K resulting from electron reflections at the metal/oxide interfaces with a part of specular reflexions.
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Condensed Matter [cond-mat]. INSA de Toulouse, 2004. French


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Submitted on : Thursday, May 26, 2005 - 3:07:43 PM
Last modification on : Thursday, December 15, 2005 - 7:14:41 AM

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Christophe Gatel. Elaboration et étude d'un système hybride "Oxyde ferrimagnétique / Métal non magnétique / Oxyde ferrimagnétique". Condensed Matter [cond-mat]. INSA de Toulouse, 2004. French. <tel-00009159v3>

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