Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MA: Fachverband Magnetismus
MA 9: Magnetic Nanoparticles
MA 9.4: Vortrag
Montag, 31. März 2014, 15:45–16:00, HSZ 401
Temperature and size dependent investigation of the spin structure in bismuth ferrite nanoparticles — •Soma Salamon1, Joachim Landers1, Werner Keune1, Marianela Escobar2, Doru Lupascu2, and Heiko Wende1 — 1Faculty of Physics and CENIDE, University of Duisburg-Essen, Duisburg, Germany — 2Institute for Materials Science and CENIDE, University of Duisburg-Essen, Essen, Germany
The size and temperature dependence of the cycloidal spin structure in multiferroic bismuth ferrite (BiFeO3) nanoparticles was examined by Mössbauer spectroscopy. Different sized particle samples (d≥50 nm) were synthesized by a wet chemical method and analyzed at different temperatures to gain insight on the temperature dependent anharmonicity of the spin cycloid. A model has been developed to evaluate the line shape of spectra, making it possible to determine the anharmonicity from high resolution experimental spectra. We found that the anharmonicity of the long range cycloidal structure decreases at higher temperatures, starting at 150-200 K and finally reaching the harmonic state at about 400 K. Using three different sized particle samples, we were also able to show a decrease of the Néel temperature from about 652 K for 1 µm particles down to 632 K for 50 nm particles, in addition to an increasingly broader distribution of Néel temperatures for decreasing particle sizes. The spin cycloid has been shown to exist in all particle samples, despite the 50 nm particles having a mean diameter that is below the period length of the cycloid (≈62 nm). This work is supported by MERCUR (Stiftung Mercator and UAMR).