We present a study of the spin dynamics of Fe4 (OCH3) 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 λ 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′ / kB =7.25 K) and to the intermultiplet separation (Δ/ kB =86.4 K) between S=5 and S=4.

Muon spin relaxation investigation of tetranuclear iron(III) Fe4(OCH3)6(dpm)6 molecular cluster / D. Procissi, P. Arosio, F. Orsini, M. Marinone, A. Cornia, A. Lascialfari. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - 80:9(2009), p. 094421.094421.

Muon spin relaxation investigation of tetranuclear iron(III) Fe4(OCH3)6(dpm)6 molecular cluster

P. Arosio
Secondo
;
F. Orsini;A. Lascialfari
Ultimo
2009

Abstract

We present a study of the spin dynamics of Fe4 (OCH3) 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 λ 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′ / kB =7.25 K) and to the intermultiplet separation (Δ/ kB =86.4 K) between S=5 and S=4.
Settore FIS/01 - Fisica Sperimentale
Settore FIS/03 - Fisica della Materia
2009
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/141544
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