Browsing by Author "Kirchner, Nadejda"

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    Analysis of magnetic excitations in molecular nanomagnets
    (2006) Kirchner, Nadejda; Dressel, Martin (Prof. Dr.)
    This PhD-thesis is about methods of modeling- and analysis of experimental data on molecular nanomagnets. It has two important results. We present the computer code developed for simulation of Frequency Domain Magnetic Resonance Spectra (FDMRS) on molecular nanomagnets in terms of the single-spin Hamiltonian model. The program enables an automatic and high precision determination of the zero-field splitting parameters of mono- and many-nuclear complexes with high spin ground state. It was successfully applied to the ZFS studies by FDMRS on various molecular magnets. Another result of this work is the new development of the generalized effective spin Hamiltonian model. Interactions of non-Heisenberg type (single-ion crystal fields and antisymmetric exchange) were introduced into the model for the first time being expressed through non-collinear tensors. The model gives reasonable results by explanation of the origin of magnetic anisotropy of a tetrameric Ni(II) cluster possessing S4 symmetry. It indicates the pronounced role of the non-compensated orbital moment in the system accompanied by collective action of the single-ion crystal fields.