Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 74: Oxide and Insulator Surfaces
O 74.2: Poster
Mittwoch, 18. März 2015, 18:15–21:00, Poster A
Initial stages of epitaxy for the growth of ultrathin MgO layers on Fe3O4/MgO(001) — •Tabea Nordmann1, Olga Schuckmann1, Timo Kuschel2, Karsten Küpper1, and Joachim Wollschläger1 — 1Physics Department, Osnabrueck University, Germany — 2CSMD, Physics Department, Bielefeld University, Germany
Magnetite (Fe3O4) is a promising candidate for electrode material in magnetic tunnel junctions (MTJs) due to its theoretically predicted 100% spin polarisation at the Fermi edge. For high quality MTJs the crystalline structure of the tunneling barrier is as important as the structure of the magnetite. An interesting insulating material for MTJs consisting of magnetite is MgO because of the small lattice mismatch between magnetite and MgO of 0.3% and the symmetry filtering effect of MgO.
In this study the influence of the substrate temperature on the growth of MgO tunneling barriers (thickness 1-3 nm) on Fe3O4(001) films was investigated. Especially the growth mode and the quality of the crystalline structure of the MgO films were analyzed. The MgO films were deposited in several steps by reactive molecular beam epitaxy (RMBE). After each step x-ray photoelectron spectroscopy (XPS) and low energy electron diffraction (LEED) were performed.
The analysis of the XPS measurements reveal island- and layer-plus-island growth at substrate temperatures between 25 ∘C to 200 ∘C and layer-by-layer growth at 250 ∘C. According to the LEED measurements the crystallinity of the MgO increases with the substrate temperature.