7th INTERNATIONAL CONFERENCE ON FERRITES

J. Phys. IV France 07 (1997) C1-601-C1-602
DOI: 10.1051/jp4:19971248

Magnetite Fe_3-δO₄ : a Stoichiometry and Structure Analysis of MBE Grown Thin Films Using NO₂ as the Oxidising Source

F.C. Voogt¹, T. Hibma¹, P.J.M. Smulders¹, L. Niesen¹, T. Fujii², P.A.A. van der Heijden³, R.J.M. van de Veerdonk³ and P.J. van der Zaag<sup>3

1</sup>  Materials Science Centre, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
²  Laboratory of Solid State Chemistry, Department of Applied Chemistry, Faculty of Engineering, Okayama University, Tshushima-naka 3-1-1, Okayama 700, Japan
³  Philips Research Laboratories Eindhoven, Prof. Holstlaan 4, 5656 AA, Eindhoven, The Netherlands

Abstract
Epitaxial single crystalline films of iron oxides have been grown on MgO(100) substrates by means of MBE. Natural Fe or ⁵⁷Fe was evaporated from alumina crucibles, and oxidised simultaneously with a dosed flux of NO₂. The resulting oxide layers have been characterised in situ with RHEED, LEED, XPS, and AES. RHEED intensity oscillations, observed during deposition of the oxides, indicate a layer-by-layer growth for all substrate temperatures between 373 and 673 K. A stoichiometry analysis with CEMS, performed ex situ, shows that it is straightforward to prepare both the stable magnetite Fe₃O₄ and the metastable maghemite Fe_3-δO₄ phases. Moreover, also al1 solid solutions in between these two extreme phases, i.e. Fe_3-δO₄ with 0<δ<1/3, could be formed. Ion beam channelling has been used to examine the epitaxy of the films. It was found that the films grow coherent on MgO(100).

© EDP Sciences 1997