Magnetic properties and proton spin-lattice relaxation in molecular clusters
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https://osnadocs.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2006060610
https://osnadocs.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2006060610
Titel: | Magnetic properties and proton spin-lattice relaxation in molecular clusters |
Autor(en): | Allalen, Mohammed |
Erstgutachter: | Apl. Prof. Dr. Jürgen Schnack. |
Zweitgutachter: | Apl. Prof. Dr. Manfred Neumann |
Zusammenfassung: | In this work we studied magnetic properties of molecular magnets of the new heteropolyanion {Cu20}, dodecanuclear cluster {Ni12}, and the heterometallic {Cr7M} wheels, in which one of the CrIII ions of Cr8 has been replaced by a Fe, Cu, Zn, Ni, ion with this extra-spin acts as local probe for the spin dynamics.Such systems have been synthesized recently and they are well described using the Heisenberg spin Hamiltonian with a Zeeman term of an applied magnetic field along the z-axis. Using the numerical exact diagonalization method, we have calculated the energy spectrum and the eigenstates for different compounds,and we have used them for reexamining the available experimental susceptibility data to determine the values of exchange parameters.We have studied the thermodynamic properties such magnetization, susceptibility, heat-capacity. At low temperature regions molecular magnets act as individual quantum nanomagnets and can display super-paramagnetic phenomena like macroscopic quantum tunneling, ground state degeneracy, level-crossing. A crucial issue for understanding these phenomena is the coupling between magnetic molecular levels and the environment such as nuclear spins. We have modeled the behavior of the proton spin lattice relaxation rate as a function of applied magnetic field for low temperatures as it is measured in Nuclear Magnetic Resonance (NMR) experiments. |
URL: | https://osnadocs.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2006060610 |
Schlagworte: | Molecular magnetism; Heisenberg model; proton spin lattice relaxation rate. |
Erscheinungsdatum: | 6-Jun-2006 |
Einreichungsdatum: | 6-Jun-2006 |
Publikationstyp: | Dissertation oder Habilitation [doctoralThesis] |
Enthalten in den Sammlungen: | FB06 - E-Dissertationen |
Dateien zu dieser Ressource:
Datei | Beschreibung | Größe | Format | |
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E-Diss562_thesis.pdf | Präsentationsformat | 2,28 MB | Adobe PDF | E-Diss562_thesis.pdf Öffnen/Anzeigen |
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