Doctoral thesis (Dissertations and theses)
Neutronenstreuuntersuchungen zur magnetischen Mikrostruktur Nd-Fe-B-basierter Nanokomposite
Bick, Jens-Peter
2014
 

Files


Full Text
JPBickDissertation.pdf
Author postprint (8.03 MB)
Disertation
Download

All documents in ORBilu are protected by a user license.

Send to



Details



Keywords :
Nanomagnetism; SANS; magnetic microstructure
Abstract :
[en] Exchange-coupled magnetic nanocomposites are considered to be promising candidates for future permanent magnet applications. These nanocomposites consist of a hard magnetic phase (based on rare-earth metal alloys), which provides high magnetic anisotropy and which is exchange coupled to a soft magnetic rare earth free phase, which provides a high saturation magnetization and Curie-temperatur. For suitable microstructures one could achieve on the one hand side dramatically increased energy products, in comparison to state-of-the-art Dy-Nd-Fe-B magnets. On the other hand side – due to the reduced amount of rare earth metals – expenses could be saved significantly. The understanding of the coercivity mechanisms in these materials is crucial for the development of nanocomposite permanent magnets. In the present work, the magnetization reversal of a two-phase Nd2Fe14B/Fe3B nanocomposite has been studied by means of magnetic small angle neutron scattering (SANS). This technique exclusively provides access to information of the magnetic microstructure in the bulk of the material and on the relevant length scales of 1 − 100 nm. Direct Fourier-transformation allowed the calculation of the correlation function of the spin misalignment C(r). From this data, the correlation length lc has been obtained. The parameter lc is a measure for the spatial extent of magnetization inhomogeneities. The field dependence of lc indicates a magnetization reversal process, which is widely governed by homogeneous rotation of the magnetization within the hard magnetic Nd2Fe14B particles. In addition, in terms of a micromagnetic approach, the exchange stiffness constant A was determined experimentally.
Disciplines :
Physics
Author, co-author :
Bick, Jens-Peter ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
Language :
German
Title :
Neutronenstreuuntersuchungen zur magnetischen Mikrostruktur Nd-Fe-B-basierter Nanokomposite
Alternative titles :
[en] Neutron-scattering investigation of the magnetic microstructure of Nd-Fe-B based nanocomposites
Defense date :
27 July 2014
Number of pages :
107
Institution :
Unilu - University of Luxembourg, Luxembourg, Luxembourg
Degree :
Docteur en Physique
Promotor :
Jury member :
Siebentritt, Susanne 
Petracic, Oleg
Birringer, Rainer
Name of the research project :
AFR Project No. 896446
Funders :
FNR - Fonds National de la Recherche [LU]
Available on ORBilu :
since 08 October 2014

Statistics


Number of views
89 (5 by Unilu)
Number of downloads
1008 (2 by Unilu)

Bibliography


Similar publications



Contact ORBilu