Regensburg 2002 – wissenschaftliches Programm

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MA: Magnetismus

MA 1: Mikro- und nanostrukturierte Materialien

MA 1.1: Hauptvortrag

Montag, 11. März 2002, 09:30–10:00, H10

Classical and quantum physics in magnetic nanostructures — •Wolfgang Wernsdorfer — LLN, CNRS, BP166, 38042 Grenoble, France

Studying the limits between classical and quantum physics has become a very attractive field of research. New and fascinating mesoscopic effects are expected. Nanometer-sized magnetic particles are situated at the frontier between classical and quantum magnetism. In addition, their magnetic properties are technologically very challenging. Our micro-SQUID technique [1] allows us to study single nanoparticles containing less than 1000 atoms. We discuss our recent results concerning the magnetization reversal of individual Co and Fe clusters (3 nm). Using a generalized Stoner-Wohlfarth model, we show that 3D measurements of the angular dependence of the magnetization reversal yield the effective magnetic anisotropy function. The latter is important for our temperature- and time-dependent studies. We discuss the transition from classical to quantum magnetization reversal and demonstrate that molecular magnets offer an unique opportunity to explore the quantum dynamics of a large but finite spin. [1] For a review, see W. Wernsdorfer, Adv. Chem. Phys., 118, 99 (2001) or http://xxx.lanl.gov/abs/cond-mat/0101104