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MA: Fachverband Magnetismus

MA 27: PhD Focus Session: Biogenic spin phenomena (joint session MA/AKjDPG)

MA 27.2: Hauptvortrag

Mittwoch, 3. April 2019, 10:15–10:45, H38

Spin-dynamics of a magnetic nanoparticle chain. — •Michael Winklhofer — Carl von Ossietzky Universitaet Oldenburg, Germany

Magnetic nanoparticle chains occur in nature as magnetosomes in magnetotactic bacteria. A typical magnetosome chain consists of 10-20 magnetite particles (Fe3O4, 35 - 60 nm particle size), whose individual magnetic dipolar moments add up to produce a stable intracellular compass needle that keeps the cell body of the bacterium aligned with the Earth' s magnetic field. The potential of magnetosomes isolated from bacteria for biomedical applications (magnetic hyperthermia and MRI) is due to the relatively large magnetic moment per particle (magnetic single-domains) and the biological membrane that surrounds each particle, thereby preventing phase separation and allowing for functionalization. Since the particles magnetically interact through dipolar coupling only, a magnetosome chain exhibits intriguing spin-wave dynamics. As will be shown here, both experimentally and theoretically, magnonic features such as band gaps depend on the geometric structure of the chain. Magnetic bacteria therefore have promising structures for applications in magnonics at the nanoscale.