H.Wende: Microscopic understanding of particle-matrix interaction in magnetic hybrid materials by element-specific spectroscopy
Description
The interaction of magnetic nanoparticles with the matrix in magnetic hybrid structures as e.g. elastomers is not understood sufficiently on a nearest neighbour lengthscale. In order to improve the fundamental understanding on this lengthscale, magnetic nanoparticles embedded in an elastic matrix shall be investigated by means of X-ray absorption spectroscopy at synchrotron radiation facilities and utilizing Mössbauer spectroscopy.
![Oben: Mittels Dichte¬funktional-theorie bestimmte Morphologie eines L10 geordneten FePt Nano-partikels in einer Al-Matrix [2]. Die Wechselwirkung mit der Al-Matrix führt zu einer starken Änderung der lokalen Struktur und damit der elektronischen Struktur.](https://tu-dresden.de/ing/maschinenwesen/imd/mfd/ressourcen/bilder/05_kooperation/spp1681-bilder/Wende.jpg/@@images/db810312-cd68-4acf-b47f-d007b8b331c7.jpeg)
Top: Morphology of a L10 ordered FePt nanoparticle embedded in an Al-matrix as determined by means of density functional theory [2]. The interaction with the Al matrix leads to a strong modification of the geometric structure and accordingly to a variatio
The X-ray absorption spectroscopy and the X-ray magnetic circular dichroism allow for the investigation of the element selective (spin-dependent) electronic structure [1]. Thereby, the bonding of the particle to the matrix and the particle-matrix interface can be characterized (see Figure) [2]. The canting of the magnetic moments at the particles’ surface can be determined by the analysis of the Mössbauer spectra in an applied magnetic field (max. 5T). This yields a more complete understanding of the interaction of the particles with the surrounding matrix. The X-ray absorption spectra as well as the Mössbauer spectra can be measured in an applied magnetic field. Thus, the hybrid structures can be investigated by these techniques directly in operation. This allows for the detection of possible changes of the particle-matrix interaction by the applied magnetic field. Furthermore, magnetic relaxation phenomena shall be studied by Mössbauer spectra in zero magnetic field. These measurements will be accompanied by thermoremanent magnetization measurements utilizing a SQUID magnetometer. Thereby, the magnetic particle-particle interaction can be characterized. It is possible to tune the dipole-dipole interaction and even to switch on/off the direct magnetic exchange in these magnetic hybrid structures by changing the particle-particle distance. This can be achieved by modification of the specific matrix and the particle concentration. The microscopic understanding achieved in this project will help to generate new functionalities of the hybrid materials by transferring this information to the groups synthesizing the systems.
Project Manager
Prof. Dr. Heiko Wende, Universität Duisburg-Essen
Staff
Joachim Landers, Universität Duisburg-Essen
Samira Webers, Universität Duisburg-Essen
Grant period
2013 -
Publications
[1] H. Wende (2004) „Recent advances in X-ray absorption spectroscopy“, Reports on Progress in Physics 67, 2105-2181.
[2] C. Antoniak et al. (2011) „A guideline for atomistic design and understanding of ultrahard nanomagnets“, Nature Communications 2, Article number: 528 .
[3] Landers, J.; Salamon, S.; Escobar Castillo, M.; Lupascu, D. C.; Wende, H. (2014) „Mössbauer Study of Temperature-Dependent Cycloidal Ordering in BiFeO3 Nanoparticles“ Nano Letters (Nano Lett.) 14, 11, 6061 - 6065
[4] Landers, J.; Stromberg, F.; Darbandi, M.; Schöppner, Ch.; Keune, W.; Wende, H. (2015) „Correlation of superparamagnetic relaxation with magnetic dipole interaction in capped iron-oxide nanoparticles“ Journal of Physics: Condensed Matter 27, 2, 026002-1 - 026002-11
Contact
Universität Duisburg-Essen
Fakultät für Physik
Experimentalphysik - AG Wende
Lotharstr. 1
47048 Duisburg