Regensburg 2013 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 17: Magnetic Particles and Clusters (jointly with CPP, BP)
MA 17.6: Vortrag
Dienstag, 12. März 2013, 11:15–11:30, H22
Cycloidal spin-structures in Bismuth iron-oxide nanoparticles — •Joachim Landers1, Soma Salamon1, Werner Keune1, Marianela Escobar2, Doru Lupascu2, and Heiko Wende1 — 1Faculty of Physics and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, Duisburg, Germany — 2Institute for Materials Science, University of Duisburg-Essen, Essen, Germany
Bismuth iron-oxide (BiFeO3, BFO) nanoparticles of various diameters d prepared by a wet chemical method were studied using Mössbauer spectroscopy to determine the influence of the particle size (d 50nm) on the cycloidal spin structure observable in BFO bulk material. Mössbauer spectra were measured at several temperatures to determine the orientation of magnetic moments relative to the crystal axes. This can be analyzed by investigating the quadrupole level shift, which was in good agreement to bulk references. Considering effects on the relative spectral intensities and the resulting effective (hyperfine) magnetic field, a model of the ideal cycloidal structure was used to simulate a theoretical spectrum consistent with experimental Mössbauer spectra measured at 4.2K in an applied magnetic field of about 5T. The combination of both methods verifies the presence of a ’bulk-like’ spin structure, which is still stable in nanoparticles with a diameter of about 54nm.