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Proton NMR and {mu}SR in Mn{sub 12}O{sub 12} acetate: A mesoscopic magnetic molecular cluster

Journal Article · · Physical Review, B: Condensed Matter
;  [1];  [2]; ;  [2];  [3]
  1. Department of Chemistry, University of Florence, Firenze (Italy)
  2. Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011 (United States)
  3. Department of Physics A. Volta, Unita INFN di Pavia, Via Bassi 6, I27100 Pavia (Italy)
The spin dynamics of Mn spins in the dodecanuclear manganese cluster of formula [Mn{sub 12}O{sub 12}(CH{sub 3}COO){sub 16}(H{sub 2}O){sub 4}]{center_dot}2CH{sub 3}-COOH{center_dot}4H{sub 2}O(Mn{sub 12}) has been investigated by {sup 1}HNMR and muon spin-lattice relaxation rate 1/T{sub 1} as a function of temperature (10{endash}400 K) and external magnetic field (0{endash}9.4 T). At room temperature, the proton 1/T{sub 1} depends on the measuring frequency. The results can be interpreted in terms of a slow decay of the Mn electronic-spin autocorrelation function, a feature characteristic of the almost zero dimensionality of the system. As the temperature is lowered, 1/T{sub 1} displays a critical enhancement that can be related to the slowing down of the local spin fluctuations as the cluster approaches the condensation into the total spin S=10 ground-state configuration. It is found that the application of an external magnetic field greatly depresses the enhancement of 1/T{sub 1} an effect that could be related to the superparamagnetic behavior of the Mn{sub 12} molecule. {copyright} {ital 1998} {ital The American Physical Society}
OSTI ID:
565890
Journal Information:
Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 1 Vol. 57; ISSN PRBMDO; ISSN 0163-1829
Country of Publication:
United States
Language:
English