Abstract: By use of spin-resolved POLARIS experiments it is planned to analyze the spin coupling between magnetic nanoparticles in 5 different types of particle clusters. With particle sizes in the range of 8 - 40 nm these particles can be regarded in all cases as single-domain particles and are aggregated to small clusters. The cluster size (~ 30 nm to a few µm) and type of arrangement (e.g. close packed clusters or linear chains) varies between the samples. Within the clusters the individual particle moments (single-domains) are strongly interacting due to dipole-dipole interactions/stray fields. It is expected that within the 5 samples the spin coupling due to dipolar interactions significantly varies, which can be verified by the proposed POLARIS experiments. The results would be of high interest regarding a wide range of potential biomedical applications of these nanoparticle clusters, such as hyperthermia, magnetic drug targeting or magnetic biosensing.

Experiment Parameters Environment temperature 300 K Experiment energy 6 Angstrom Experiment moment 0.01 - 1 [1/nm] Experiment res energy 10 % Experiment res moment - Sample Parameters Formula Fe2O3/Fe3O4 in H20 (sample3) Fe2O3/Fe3O4 in H20 Fe2O3/Fe3O4 in H20 (sample2) Fe2O3/Fe3O4 in H20 (sample4) Bacteria Magnetospirillum gryphiswaldense + Fe3O4- nanoparticles in H2O

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