Muon spin relaxation investigation of tetranuclear iron(III) Fe_4(OCH_3)_6(dpm)_6 molecular cluster
Abstract
We present a study of the spin dynamics of Fe_4(OCH_3)_6(dpm)_6 single molecule magnet by means of SQUID magnetization and muon relaxation (µ^(+)SR) measurements. In longitudinal field µ^+SR experiments performed at magnetic fields H=200, 1000 Oe, the muon asymmetry P(t) could be fitted by means of three components, the first constant, the second fast relaxing through a quasiexponential decay, and the third, the slowest relaxing, showing an exponential decay. The slowest muon relaxation rate studied as a function of temperature T displayed two structures, a broad peak at T~15/20 K and a shoulder at T<5 K, both decreasing in amplitude and displacing toward higher temperatures as the field is increased. To mimic qualitatively the temperature behavior λ(T) at the investigated fields, we used a function expressed as the sum of two Bloembergen-Purcell-Pound (BPP)-like laws, reproducing the mechanism of relaxation. The exponential data resulted well fitted by means of a heuristic model which takes into account two correlation times τ' and τ, related to the ground-state multiplet barrier (Δ'/k_B=7.25 K) and to the intermultiplet separation (Δ'/k_B=86.4 K) between S=5 and S=4.
Additional Information
© 2009 American Physical Society. Received 3 April 2009; revised 25 June 2009; published 29 September 2009. Magmanet Network of Excellence and QuEMolNa Research Training Network are gratefully acknowledged. P. Carretta and E. Micotti are thanked for help in experimental measurements and S. P. J. Cottrell for technical assistance.Additional details
- Eprint ID
- 16437
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- CaltechAUTHORS:20091022-094602971
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2009-10-23Created from EPrint's datestamp field
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2021-11-08Created from EPrint's last_modified field