Berlin 2005 – wissenschaftliches Programm
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MA: Magnetismus
MA 24: Oberfl
ächenmagnetismus
MA 24.3: Vortrag
Dienstag, 8. März 2005, 11:00–11:15, TU A060
Ultrathin Ni films grown with O surfactant: Structure and Magnetism — •C. Sorg, N. Ponpandian, A. Scherz, R. Nünthel, T. Gleitsmann, K. Baberschke, and H. Wende — Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin-Dahlem, Germany
We have studied ultrathin Ni films grown on Cu(100) and Cu(110) with and without O surfactant using element specific XAS and XMCD at the O K edge as well as at the Ni L2,3 edges [1]. The O surfactant improves the growth mode of these films towards a better layer-by-layer growth and leads to a reduced surface roughness [2]. Since the O surfactant reduces also the surface anisotropy energy, the spin reorientation transition is shifted to a lower Ni thickness on Cu(100) [3]. On the more open and anisotropic Cu(110) surface an out-of-plane phase exists only if O is present on the Ni films. By means of XAS, we give final evidence that no bulk-like NiO is formed and that the O stays on top of the Ni films. We observe a charge transfer from Ni to O states. With XMCD we investigate the Ni orbital and spin moments. On the Cu(100) surface the total Ni magnetization of thinner films is reduced compared to the bulk. In contrast, on Cu(110) we observe an enhancement which is mainly carried by the orbital moment. Finally, we determine an induced magnetic orbital moment of the oxygen parallel to the one of Ni by analyzing the XMCD at the O K edge. – Supported by BMBF (05 KS4 KEB 5).
[1] C. Sorg et al., Surf. Sci. 565, 197 (2004).
[2] R. Nünthel et al., Surf. Sci. 531, 53 (2003); ibid. 566-568, 100 (2004).
[3] J. Hong et al., Phys. Rev. Lett. 92, 147202 (2004).