Open this publication in new window or tab >>2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]
In this thesis the magnetic and structural properties of ultra-thin 3d transition metals films have been investigated, in particular Fe, Ni and Co films. X-ray Magnetic Circular Dichroism (XMCD) has provided element specific spin (ms ) and orbital (ml ) moments per atom by utilizing the magneto optic sum-rules. Element specific hysteresis curves have been measured by means of X-ray Resonant Magnetic Scattering (XRMS), and the local crystallographic structure has been investigated using Extended X-ray Absorption Fine Structure (EXAFS).
By performing XMCD on Fe/Ag(100) we observe a spin reorientation from in-plane to out-of-plane as the Fe thickness is lowered. At temperatures below 300K it occurs around 5-7 mono layers (ML) of Fe. While reorienting the magnetization out-of-plane the orbital moment increases with 125% but only a minor increase (5%) of the spin moment is observed. Extended X-ray Absorption Fine Structure (EXAFS) measurements indicate that films 6 ML and thicker have a bulk-like bcc structure. For the thin out-of-plane films, the local crystallographic structure is more complicated.
The spin reorientation of the Au/Co/Au tri-layer system has been studied as a function of temperature, Co layer and Au cap thickness. An unexpected behavior of the orbital moment upon spin reorientation is found in these systems. An ex-situ prepared sample shows a smooth spin reorientation from an in-plane to an out-of-plane easy magnetization direction as the temperature is lowered from 300K to 200K. In-situ prepared samples have also been investigated and a novel phase diagram has been identified. The Au/Co interface has been explored during the Au capping by means of photoemission measurements.
In the bi- and tri-layer system of Fe and Ni we have been able to manipulate the spin reorientation by varying the Fe and Ni thickness. A novel non-collinear interlayer exchange interaction for 3d ferro magnets in direct contact has been discovered for a set of samples. This exchange interaction is found to be strongly dependant on the preparation conditions.
Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. p. v + 47
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 175
Keywords
Physics, thin film, xmcd, xrms, exafs, anisotropy, magnetism, Fe, Ni, Co, Ag, Cu, Fysik
Identifiers
urn:nbn:se:uu:diva-6836 (URN)91-554-6554-4 (ISBN)
Public defence
2006-05-24, Polhemsalen, Ångströmlabratoriet, Lägerhyddsvägen 1, Uppsala, 10:15
Opponent
Supervisors
2006-05-032006-05-032013-09-18Bibliographically approved