Theoretical estimates for proton-NMR spin–lattice relaxation rates of heterometallic spin rings
Heterometallic molecular chromium wheels are fascinating new magnetic materials. We reexamine the available experimental susceptibility data on MCr 7 wheels in terms of a simple isotropic Heisenberg Hamiltonian for M=Fe, Ni, Cu, and Zn and find in that FeCr 7 needs to be described with an iron–chrom...
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Veröffentlicht in: | Journal of magnetism and magnetic materials 2006-07, Vol.302 (1), p.206-210 |
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Hauptverfasser: | , |
Format: | Artikel |
Sprache: | eng |
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Online-Zugang: | Volltext |
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Zusammenfassung: | Heterometallic molecular chromium wheels are fascinating new magnetic materials. We reexamine the available experimental susceptibility data on MCr
7 wheels in terms of a simple isotropic Heisenberg Hamiltonian for M=Fe, Ni, Cu, and Zn and find in that FeCr
7 needs to be described with an iron–chromium exchange that is different from all other cases. In a second step we model 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. It appears that CuCr
7 and NiCr
7 show an unexpectedly reduced relaxation rate at certain level crossings. |
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ISSN: | 0304-8853 |
DOI: | 10.1016/j.jmmm.2005.09.006 |