Dresden 2003 – scientific programme
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MA: Magnetismus
MA 25: Spinabh
ängige Transportph
änomene I
MA 25.8: Talk
Thursday, March 27, 2003, 17:00–17:15, HSZ/04
Structure and morphology of the Fe/MgO/Fe(001)-tunneling-magneto-resistance junction — •H. L. Meyerheim1, R. Popescu1, D. Ullmann1, J. Kirschner1, and N. Jedrecy2 — 1MPI f. Mikrostrukturpyhsik, Weinberg 2, D-06120 Halle — 2LMCP Univ. Paris VI, 4 place Jussieu, F-75252 Paris
The epitaxial Fe/MgO/Fe(001) system has attracted considerable interest due to its potential applicability in tunneling-magneto- resistance (TMR) devices. In a previous study we have carried out surface x-ray diffraction (SXRD) measurements on the MgO/Fe(001) interface [1]. In this contribution we discuss STM and SXRD experiments on the second interface, [Fe/(2ML MgO)]/Fe(001). Due to the different surface energies (MgO: 1.1 J/m2, Fe:2.9 J/m2) 3D island growth of Fe on MgO is observed. The SXRD analysis of a 2 ML Fe layer deposited at room temperature in UHV on 2ML MgO/Fe(001) indicates, that only a minor fraction (<0.3ML) of Fe is in registry (Fe on top of O) with the underlying structure. Morphology and structure of the Fe/MgO interface are different if Fe is deposited in pO2 ×10−7 mbar. In this case two (partially occupied) FeO-layers are formed before Fe-island growth sets in. Growth of thicker Fe-layers (ca. 5ML) followed by annealing at 300 C results in a network like surface morphology, which is characterized by meandering terraces of 10nm width and 1.5 nm height.
[1] H. L. Meyerheim et al. PRL 87, 076102 (2001)