Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 12: FS: Single Nanomagnets

MA 12.1: Topical Talk

Dienstag, 23. März 2010, 10:45–11:15, H22

Exploring the frontiers in cluster magnetism from a theorist’s perspective — •Gustavo Pastor — Institut für Theoretische Physik, Universität Kassel, Germany

In past years a remarkable progress has been achieved in the experimental synthesis and characterization of magnetic clusters, which renders increasingly rigorous comparisons between realistic (experimental) and idealized (theoretical) nanostructures possible. These investigations concern in particular magnetic phenomena that are specific to single clusters. The purpose of this talk is to discuss some of the current theoretical challenges in the theory of cluster magnetism. The specific subjects to be explored are strong electron correlation effects, finite-temperature spin fluctuations and magnetic anisotropy energy (MAE). The problem of local moment formation and Kondo effect of transition-metal impurities in finite NiCuN and CoCuN metal clusters is investigated. First principles calculations show that the Ni or Co impurities preserve their magnetic degree of freedom and are therefore good candidates for developing interesting many-body phenomena. The temperature dependence of the magnetic properties of FeN clusters (N ≤ 24) are determined in the framework of a functional-integral itinerant-electron theory. A remarkable dependence of the average magnetic moment per atom Δ N(T) on size and structure is observed. CoRh alloy nanoparticles show non-trivial correlations between chemical and magnetic order that lead to a non-monotonous dependence of the MAE as a function of composition, yielding a perspective of tailoring the MAE of nanoalloys.