Search: onr:"swepub:oai:DiVA.org:uu-3940" >
Growth and Magnetic...
Growth and Magnetic Properties of Fe- and FeNi-based Thin Films and Multilayers
-
- Blixt, Anna Maria, 1969- (author)
- Uppsala universitet,Fysiska institutionen
-
Hjörvarsson, Björgvin (thesis advisor)
-
Andersson, Gabriella (thesis advisor)
-
show more...
-
- Poulopoulos, Panagiotis, Doctor (opponent)
- Materials Science Department, University of Patras, Patras
-
show less...
-
(creator_code:org_t)
- ISBN 9155458491
- Uppsala : Acta Universitatis Upsaliensis, 2004
- English 62 s.
-
Series: Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1104-232X ; 927
- Related links:
-
https://uu.diva-port... (primary) (Raw object)
-
show more...
-
https://urn.kb.se/re...
-
show less...
Abstract
Subject headings
Close
- This thesis concerns the growth and magnetic properties of thin films and multilayers. The samples were grown by magnetron sputtering, and characterized structurally mainly by x-ray diffraction and reflectivity. The magnetic characterization of the multilayers was done by magneto-optical Kerr technique, SQUID magnetometry and, in two samples, by neutron reflectometry.Arrays of small elements of polycrystalline permalloy (FeNi alloy with 19 wt% Fe) are of interest as a component in non-volatile magnetic random access memories (MRAM). Here the shape dependence of the domain structure in such elements was studied by magnetic force microscopy (MFM) and in thin ring magnets the 'onion' state could be seen for the first time. Also, by post-annealing in hydrogen atmosphere the number of domains decreased in each element due to enhanced relaxation and defect reduction.Furthermore, permalloy-based anisotropic magnetoresistance (AMR) in read heads are nowadays replaced by material combinations that have a giant magnetoresistance (GMR) effect. In this work Fe/V(001) and Fe0.82Ni0.18/V(001) superlattices, i.e. single-crystal-like multilayers, were investigated. These systems showed much smaller GMR effect compared to the Fe/Cr system. However, by introducing Ni into the Fe layers the magnetic anisotropy and the interlayer exchange coupling (IEC) decreased, thereby increasing the sensitivity, which is a key property for a magnetic sensor. The interface region showed a reduced magnetic moment, and the influence of the structural quality was modelled and investigated theoretically in the Fe0.82Ni0.18/V case. Also, in the Fe(2-3 ML)/V(x ML) superlattices (ML=monolayers) the transition temperature from long-range magnetic order to paramagnetic order oscillated with the V layer thickness (x) as a result of the oscillatory behaviour of the IEC.The introduction of hydrogen in the non-magnetic layers of, for example, Fe/V(001) superlattices is a way to tune the IEC strength. Here the tuning was used as a tool to study the magnetic order in a low-dimensional magnet. At the critical hydrogen concentration =0.022 the Fe layers in an Fe(2 ML)/V(13 ML) superlattice became decoupled. Then the system behaved as a two-dimensional Ising magnet with a finite ordering temperature of about 60 K.
Subject headings
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Keyword
- Physics
- Sputter growth
- Permalloy
- Multilayer
- Superlattice
- Magnetism
- Fysik
- Physics
- Fysik
Publication and Content Type
- vet (subject category)
- dok (subject category)
Find in a library
To the university's database