| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
|
|
| 5. |
- Blixt, Anna Maria, 1969-
(författare)
-
Growth and Magnetic Properties of Fe- and FeNi-based Thin Films and Multilayers
- 2004
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
|
|
| 14. |
- Kaså, Sophia, et al.
(författare)
-
CIRA: cirkulär och inkluderande renovering av allmännyttan : Synergier och förflyttning i systemförändringen mot en hållbarare ROT-process
- 2024
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trots att cirkulär byggnation och boendes inkludering i bygg- och renoveringsprocesser studerats mycket var för sig, är kombinationen relativt outforskad. Målet med detta projekt var att se vilka synergier som kunde uppstå för ett allmännyttigt bostadsbolag om man arbetade fram en cirkulärare och mer inkluderade ROT-process.Utifrån ett tätt samarbete mellan kommun, fastighetsägare, arkitektkontor och forskningsinstitut utforskades vad en cirkulär och inkluderande ROT-process kunde vara. Genom en innovationsprocess som bland annat innefattade kompetenshöjande insatser, workshops, studiebesök, intervjuer, observationer och olika sorters testning, så utvecklades en gemensam förståelse för den nya processen. En prototyp för en cirkulär och inkluderande ROT-process utformades, som kom att kallas CIRA-processen.Slutsatserna av arbetet blev att det är i de tidiga faserna av ett projekt som cirkulär och inkluderande riktning och strategi måste tas fram. Upphandlingen kommer in tidigare än i en traditionell ROT-process och efter det tar man tillsammans fram nyckeltal och projektmål och utför grundliga inventeringar av den fastigheten projektet gäller. Ytterligare en slutsats är att arbetet behöver göras i partnerskap med alla berörda aktörer, inte minst boende och entreprenörer. I rapporten beskrivs innovationsprocessen och den framtagna CIRA-processen i detalj.
|
|
| 15. |
|
|
| 16. |
- Kazakova, Olga, et al.
(författare)
-
Magnetic properties of submicron permalloy elements : Effects of heat treatment
- 2003
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:10, s. 7334-7336
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of the effect of annealing in hydrogen atmosphere on the magnetic properties of continuous magnetic films and patterned structures. Rectangular and elliptical particles, with lateral dimensions in the range 150–900 nm, were made of 24 and 66 nm thick permalloy films. The domain structure and the magnetization reversal processes were investigated by magnetic force microscopy and alternating gradient magnetometry. While the performed annealing at 200 °C during 48 h did not noticeably change the properties of the continuous films, it influenced the patterned structures significantly. The difference between patterned elements and the continuous films can be explained by enhanced relaxation and vacancy diffusion in the particles
|
|
| 17. |
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
- Ryazhkin, A. V., et al.
(författare)
-
Local atomic structure of Fe-Ni/V multilayer nanostructures : EXAFS spectroscopy and synchrotron radiation data
- 2008
-
Ingår i: Journal of Structural Chemistry. - : Springer Science and Business Media LLC. - 0022-4766 .- 1573-8779. ; 49:1, s. S129-S137
-
Tidskriftsartikel (refereegranskat)abstract
- Fe, Ni, and V K EXAFS spectroscopic experiments were carried out at the European Synchrotron Radiation Center (ESRF) in the fluorescent mode on the 26 angstrom line with the use of the [(Fe82Ni18)(5)/V-6](25) and [(Fe82Ni18)(10)/V-6](25) samples of multilayer nanoheterostructures prepared by magnetron spraying (at Uppsala University). The partial interatomic distances were determined by the regularization technique. The existing distortions of the bee lattice in (Fe82N18)/V multilayer nanostructures depend strongly on the thickness of the ferromagnetic layers of the permalloy and also affect vanadium layers.
|
|
| 21. |
- Skubic, Björn, et al.
(författare)
-
Magnetic moments and exchange interactions in Fe0.82Ni0.18/V bcc(001) multilayers
- 2004
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:9, s. 094421-
-
Tidskriftsartikel (refereegranskat)abstract
- The magnetic ordering and average magnetization of multilayers are greatly affected by the interface structure of the system. In this paper, interface effects are discussed, and their impact on the amplitude and period of the interlayer exchange coupling and the magnetic moments are investigated for the Fe0.82Ni0.18∕V body-centered-cubic (001) system. By modeling these effects by first principles calculations we find good agreement with experiments over the whole investigated range of layer thicknesses. In addition, as different interface effects give different fingerprints on the interlayer exchange coupling and magnetization, we are able to make an estimate of the interface structure of the different experimental samples by comparing experiment to theory.
|
|
