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Structure and morphology of NiO / Cu(111) and NiO /FeNi / Cu(111) ultra-thin layers and nanostructures

Abstract : The very first stages of the growth of NiO/Cu(111) interface, were characterized on a microscopic scale including chemical, morphological, and structural aspects. Different elaboration procedures were used and we combined in-situ laboratory and synchrotron radiation techniques. Complete exchange coupled NiO/FeNi/Cu(111) bilayer system have also been investigated. The metallic Ni/Cu(111) interface has been studied, evidencing the close relationship between morphology, structure and magnetic properties. The reduced spin magnetic moments were correlated with the Ni-Cu 3d hybridization and with the Cu capping. The in-plane orbital moment anisotropy, related with the Ni tetragonalization, confirms that the easy axis of magnetization is in the plane for all measured thin nickel films. Ultra-thin NiO films, obtained through MBE evaporation of NiO nuggets, were grown at room temperature and at 250°C. The resulting system can globally be described in terms of a spontaneous NiO/Ni/Cu(111) layering. Confirming the STM real-space observations, GISAXS experiments and calculations allowed evidencing the self-organized nature of the NiO islands obtained at room temperature. Due to the poor oxidizing efficiency of the molecular oxygen, the NiO films deposited from metallic Ni at 250°C, exhibit several differences with respect to those obtained by NiO nuggets evaporation at room temperature. A cluster nucleation/aggregation mechanism was proposed, based on the STM observations. Formation of alpha-Ni2O3 hexagonal phase, or structural distortion of the NiO(111)(sqrt(3)xsqrt(3))R30° structure could both explain the LEED and GIXD results. Exchange coupled NiO/FeNi/Cu(111) bilayer was elaborated using both, NiO nuggets and metallic Ni in oxygen partial pressure evaporation. Sharp NiO/FeNi interfaces were obtained, with textured NiO. Structural analysis of the NiO films deposited on FeNi/Cu(111) films evidenced twinned NiO(111), in much better epitaxy than the oxides deposited on the Cu(111) substrate.
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https://tel.archives-ouvertes.fr/tel-00010139
Contributor : Stefan Stanescu <>
Submitted on : Wednesday, September 14, 2005 - 6:43:46 PM
Last modification on : Thursday, April 23, 2020 - 2:26:22 PM
Long-term archiving on: : Friday, April 2, 2010 - 9:58:24 PM

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  • HAL Id : tel-00010139, version 1

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Stefan Stanescu. Structure and morphology of NiO / Cu(111) and NiO /FeNi / Cu(111) ultra-thin layers and nanostructures. Condensed Matter [cond-mat]. Université Louis Pasteur - Strasbourg I, 2002. English. ⟨tel-00010139⟩

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