Spin dynamics of the giant polyoxometalate molecule {Mn40W224} studied by NMR

7Li nuclear magnetic resonance (NMR) studies have been performed to investigate magnetic properties and spin dynamics of Mn3+ (S = 2) spins in the giant polyoxometalate molecule {Mn40W224}. The 7Li-NMR line width is proportional to the external magnetic field H as expected in a paramagnetic state ab...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2014-05, Vol.26 (19), p.196003-196003
Main Authors: Furukawa, Y, Fang, X, Kögerler, P
Format: Article
Language:English
Subjects:
Condensed matter
Fluctuation
Freezing
Magnetic fields
Magnetic properties
Magnetic Resonance Spectroscopy
Models, Molecular
Molecular Conformation
molecular magnet
NMR
Nuclear magnetic resonance
Spin dynamics
Temperature
Temperature dependence
Tungsten Compounds - chemistry
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Summary:7Li nuclear magnetic resonance (NMR) studies have been performed to investigate magnetic properties and spin dynamics of Mn3+ (S = 2) spins in the giant polyoxometalate molecule {Mn40W224}. The 7Li-NMR line width is proportional to the external magnetic field H as expected in a paramagnetic state above 3 K. Below this temperature the line width shows a sudden increase and is almost independent of H, which indicates freezing of the local Mn3+ spins. The temperature dependence of T1 for both 1H and 7Li reveals slow spin dynamics at low temperatures, consistent with spin freezing. The slow spin dynamics is also evidenced by the observation of a peak of 1/T2 around 3 K, where the fluctuation frequency of spins is of the order of ∼200 kHz. An explicit form of the temperature dependence of the fluctuation frequency of Mn3+ spins is derived from the nuclear relaxation data.
ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/26/19/196003