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Phonon bottleneck effect leads to observation of quantum tunneling of the magnetization and butterfly hysteresis loops in (Et₄N)₃Fe₂F₉

Schenker, R. and Leuenberger, M. N. and Chaboussant, G. and Loss, D. and Gudel, H. U.. (2005) Phonon bottleneck effect leads to observation of quantum tunneling of the magnetization and butterfly hysteresis loops in (Et₄N)₃Fe₂F₉. Physical Review B, Vol. 72, H. 18 , 184403, 10 S..

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Official URL: http://edoc.unibas.ch/dok/A5254651

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Abstract

A detailed investigation of the unusual dynamics of the magnetization of (Et4N)(3)Fe2F9 (Fe-2), containing isolated [Fe2F9](3-) dimers, is presented and discussed. Fe-2 possesses an S=5 ground state with an energy barrier of 2.40 K due to an axial anisotropy. Poor thermal contact between sample and bath leads to a phonon bottleneck situation, giving rise to butterfly-shaped hysteresis loops below 5 K concomitant with slow decay of the magnetization for magnetic fields H-z applied along the Fe-Fe axis. The butterfly curves are reproduced using a microscopic model based on the interaction of the spins with resonant phonons. The phonon bottleneck allows for the observation of resonant quantum tunneling of the magnetization at 1.8 K, far above the blocking temperature for spin-phonon relaxation. The latter relaxation is probed by ac magnetic susceptibility experiments at various temperatures and bias fields H-DC. At H-DC=0, no out-of-phase signal is detected, indicating that at T <= 1.8 K Fe-2 does not behave as a single-molecule magnet. At H-DC=1 kG, relaxation is observed, occurring over the barrier of the thermally accessible S=4 first excited state that forms a combined system with the S=5 state.
Faculties and Departments:05 Faculty of Science > Departement Physik > Physik > Theoretische Physik Mesoscopics (Loss)
UniBasel Contributors:Loss, Daniel
Item Type:Article, refereed
Bibsysno:Link to catalogue
Publisher:American Institute of Physics
ISSN:0163-1829
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:22 Mar 2012 14:25
Deposited On:22 Mar 2012 13:48

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