Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 22: Magnetische dünne Schichten IV
MA 22.2: Vortrag
Dienstag, 8. März 2005, 10:45–11:00, TU H1012
Morphology, structure and magnetic properties of NixMn1−x and NixMn1−x/Co bilayers grown on Cu(001) — •C. Tieg1, S. Wang1, W. Kuch1,2, and J. Kirschner1 — 1Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle — 2present address: Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin
Thin films of NixMn1−x were epitaxially grown by thermal evaporation on Cu(001) and studied with respect to their morphology, structure, and magnetic properties by means of electron diffraction techniques and magneto-optic Kerr effect measurements. A 2-dimensional growth mode has been verified for coverages up to 15 monolayers (ML) by the presence of MEED oscillations within the composition range of 0.4<x<1.0. While chemically disordered Ni-rich and Mn-rich films exhibit a p(1×1) structure, films in the equiatomic region display a characteristic c(2×2) superstructure for thicknesses within the studied range of up to 18 ML that might be attributed to an ordered L10 phase as it is present in bulk NiMn. Furthermore, the interlayer spacing d was deduced from a kinematic analysis of LEED I(V) curves taken at thick NixMn1−x films (>10 ML). We obtain a continuously decreasing d from 1.92±0.02 Å for highly Mn-rich films to 1.73±0.02 Å for tetragonally distorted pure Ni films. The lattice constants of NixMn1−x and Cu(001) coincide at x≈ 0.6. Magnetic properties were studied for NixMn1−x films in contact with a ferromagnetic layer. The presence of antiferromagnetic order in equiatomic NiMn films at T=300 K above a certain thickness is indicated by a pronounced coercivity enhancement in Co/NiMn bilayers.