Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 13: Spinabh
ängiger Transport I
MA 13.8: Vortrag
Samstag, 5. März 2005, 12:30–12:45, TU EMH225
Growth and x-ray analysis of Fe/MgO/Fe(100) layers — •Christian Tusche1, Holger Meyerheim1, Jürgen Kirschner1, Nathalie Jedrecy2, and Gilles Renaud3 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, D-06120 Halle — 2LMCP Univ. Paris VI, 4 place Jussieu, F-75252 Paris — 3CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble
For the theoretical understanding of epitaxial tunneling-magneto-resistance (TMR) systems, a detailed knowledge of the geometrical structure at the FM/insulator interface plays a crucial role. As reported before for the prototype Fe/MgO/Fe(100) system, a FeOx (x≈ 0.6) interface layer in formed during MgO deposition onto Fe(100), significantly affecting the TMR effect[1,2]. Surface x-ray diffraction (SXRD) experiments on the structure of the second Fe/MgO interface were carried out at the European Synchrotron Radiation Facility (ESRF).
While for deposition of about 0.5ML Fe in oxygen background pressure pO2 = 10−7 mbar a stoichiometric FeO interface is formed, for Fe-deposition under UHV conditions a substoichiometric FeOx (x≈ 0.3) layer grows on an oxygen depleted MgO-layer. Furthermore, well defined layer by layer growth of subsequently deposited Fe is only observed in the case of the oxygen saturated MgO/FeO interface.
Our results may have considerable importance for the optimization of the Fe/MgO/Fe(100) TMR structure, since the symmetry of the TMR geometric structure is decisive for the TMR-amplitude.
[1] H.L. Meyerheim et al., Phys. Rev. Lett 87 (2001) 076102
[2] W.H. Butler et al., Phys. Rev. B 68 (2003) 092402