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| Home > Publications database > Spin-reorientation transition in epitaxial Ni$_{x}$Pd$_{1-x}$ fims on Cu(001): a microscopic analysis |
| Home > Publications database > Spin-reorientation transition in epitaxial Ni$_{x}$Pd$_{1-x}$ fims on Cu(001): a microscopic analysis |
| Dissertation / PhD Thesis/Book | FZJ-2015-04881 |
2015
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
Jülich
ISBN: 978-3-95806-049-4
Please use a persistent id in citations: http://hdl.handle.net/2128/8990
Abstract: This thesis deals with the spin-reorientation transition (SRT) usually observed at moderate thicknesses of 35-70ML in Ni and NiPd thin films on Cu(001) and the connectionbetween domain formation and anisotropy. The intrinsic properties of the magnetic anisotropy in thin lms and native states, characterized by their domain formations, are of high interest in the framework of spintronics. Thin lm epitaxial systems are used to approach a model system behavior, therefore Cu(001) single crystals are prepared in a high surface quality and epitaxial Ni and NiPd films were grown in-situ by molecular beam epitaxy. The domain formations are studied on demagnetized films by utilizing the x-ray magnetic circular dichroism on a synchrotron based, energy filtered, and aberration corrected x-ray photoemission electron microscope. Synchrotron light is used as a multi-purpose tool with element selectivity and high flux, enabling one to determine the magnetization direction by dipole selection rule geometries. A lateral change of the effective anisotropy was achieved by employing a wedged film geometry, resulting in unique continuous measurements on the perpendicular magnetic anisotropy (PMA) area including the SRT area (0-100 ML) in Ni/Cu(001). A new domain formation of rectangularly ordered domains with domain walls aligning along the <110>-axes was found in the vicinity of the SRT and is attributed to the increasing influence of planar anisotropies, found to be in a very good agreement with theoretical models and simulations. The domain formation throughout the SRT is observed for the first time and identified as a canted state transition. Ni-like NiPd films were grown in order to vary the film-strain, the major driving parameter for the PMA and SRTs, yielding domain formations of similar characteristics up to Pd-concentrations of 12%. The behavior of NiPd films exhibiting compressive strain was investigated, verifying theoretical predictions that no SRT or PMA can be found throughout the whole thickness range of 0-60 ML. Offsetting the elemental wedges made it possible to observe acomposition-driven SRT. While the varied parameter range results in a strongly varied domain formation, in-plane anisotropy influence and a canted state could be found again. In the framework of the observed domain formations in the microscopic setup, a discussion of the T$_{c}$ drop at the SRT concludes this thesis. While being frequently reported, we could not find any hints for its existence in various examined SRTs.
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