Regensburg 2004 – scientific programme

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MA: Magnetismus

MA 4: Oberfl
ächenmagnetismus

MA 4.1: Talk

Monday, March 8, 2004, 10:15–10:30, H22

Structure and magnetism in the MnCu/Cu(001)-c(2x2) and p2gg-(4x2) surface alloys — •Popescu R.¹, Meyerheim H.L.¹, Sander D.¹, Ernst A.¹, Robach O.², Ferrer S.², Kirschner J.¹, and Bruno P.¹ — ¹MPI für Mikrostrukturphysik, Weinberg 2, 06120 Halle, Germany — ²ESRF, BP 220, F-38043 Grenoble, France

The two-dimensional magnetic alloy phases formed by deposition of Mn on Cu(001) in the coverage range between about 0.5 and 1 monolayer (ML, 1ML=1.53×10¹⁵ atoms/cm²) were investigated by surface x-ray diffraction (SXRD) and calculations based on the full potential layered Korringa-Kohn-Rostoker-method implemented within the DFT. While for the c(2x2) phase formed at 0.5 ML the basic two dimensional alloy structure model with Mn-atoms replacing every other Cu surface atom is confirmed (Mn at 0.20± 0.05 Åabove the Cu-layer), in detail an accurate fit to the 228 reflections (unweighted R≈ 0.07) is only obtained by taking into account 0.5 ML of Cu atoms above the alloy layer and a fraction of 20 percent anti-phase domains. The calculations show, that the magnetic moment of the Mn-atoms is in the 3.8 µ_B-range independent of the presence or absence of the Cu-adlayer. The p2gg-(4x2) superstructure is also characterized by a single Mn_xCu_1−x alloy layer, where the Mn-concentration (x) is in the range of about 0.8 and the corrugation in the 0.4Årange. The implications of the increased Mn-concentration (x) on the magnetic moment is discussed.