Thèse de Rémi Maurice, LCPQ : juin 2011

"Zero-Field Anisotropic Spin Hamiltonians in First-row Transition Metal Complexes : Theory, Models and Applications"

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Abstract : Magnetic anisotropy is responsible for the slow relaxation of the magnetization in single molecule magnets. The main goal of this work is to understand the factors that govern local and intersite anisotropies in polynuclear compounds. For this purpose, correlated relativistic calculations are performed in mono- and bi-nuclear species. The main degrees of freedoms of the two-step state-interaction ab initio method have been optimized in order to obtain anisotropic parameters in good agreement with the spectroscopic data. The effective Hamiltonian theory provides a universal procedure of extraction of these parameters. It has therefore been used to check the accuracy of the standard model and to propose improved models when necessary. Finally, the anisotropy parameters have been rationalized in several cases by using the quasi-degenerate perturbation theory.

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