Regensburg 2016 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 39: Magnetic Particles
MA 39.14: Vortrag
Donnerstag, 10. März 2016, 13:00–13:15, H31
ferromagnetic resonance spectroscopy of magnetotactic bacteria — •Sara Ghaisari1, Stefan Klumpp2, and Damien Faivre1 — 1Max Planck Institute of Colloids and Interfaces — 2Institut für Nichtlineare Dynamik, Georg-August-Universität Göttingen
Magnetotactic bacteria (MTB) are micro-organisms capable of forming intracellular magnetic nanoparticles inside vesicles called magnetosomes. Magnetosomes consist of a lipid membrane surrounding a ferromagnetic crystal, which is magnetite Fe3O4 or greigite Fe3S4. The size of the particles (40-100 nm) provides the organisms with a permanent magnetization. In addition, these particles are arranged into a chain such that their dipole moments add up, resulting in a strong enough magnetic moment to get aligned in the Earth*s magnetic field. Due to these unique magnetic and morphology properties, magnetosome particles are attracting interests in many interdisciplinary areas. One key advantage is the strong uniaxial anisotropy and restricted direction of magnetization. Ferromagnetic Resonance (FMR) is a powerful tool for determining the magnetic anisotropies of a ferromagnetic material. Here, we use FMR to investigate and characterize magnetosomes in different strains of magnetotactic bacteria. Different spectra are observed for different strains that can be correlated to the organization of particles and crystalline structure observed by electron microscopy. Simulations of the FMR spectra using an ellipsoid model and their quantitative comparison with the experimental spectra are used to interpret different magnetic parameters and their effect on the spectrum.