We present a study of the spin dynamics of Fe4(OCH3)6(dpm)6 single molecule magnet by means of SQUIDmagnetization and muon relaxation (mu+SR) measurements. In longitudinal field mu+SR experiments performedat 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 Lambda studied as a function of temperature Tdisplayed two structures, a broad peak at T ca. 15/20 K and a shoulder at T < 5 K, both decreasing in amplitudeand displacing toward higher temperatures as the field is increased. To mimic qualitatively the temperaturebehavior Lambda(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 bymeans of a heuristic model which takes into account two correlation times tau' and tau, related to the ground-statemultiplet barrier (Delta'/kB=7.25 K) and to the intermultiplet separation (Delta/kB=86.4 K) between S=5 andS=4.
Muon Spin Relaxation Investigation of Tetranuclear Iron(III) Fe4(OCH3)6(dpm)6 Molecular Cluster / D., Procissi; P., Arosio; F., Orsini; M., Marinone; Cornia, Andrea; A., Lascialfari. - In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. - ISSN 1098-0121. - STAMPA. - 80:(2009), pp. 094421-1-094421-6. [10.1103/PhysRevB.80.094421]
Muon Spin Relaxation Investigation of Tetranuclear Iron(III) Fe4(OCH3)6(dpm)6 Molecular Cluster
CORNIA, Andrea;
2009
Abstract
We present a study of the spin dynamics of Fe4(OCH3)6(dpm)6 single molecule magnet by means of SQUIDmagnetization and muon relaxation (mu+SR) measurements. In longitudinal field mu+SR experiments performedat 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 Lambda studied as a function of temperature Tdisplayed two structures, a broad peak at T ca. 15/20 K and a shoulder at T < 5 K, both decreasing in amplitudeand displacing toward higher temperatures as the field is increased. To mimic qualitatively the temperaturebehavior Lambda(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 bymeans of a heuristic model which takes into account two correlation times tau' and tau, related to the ground-statemultiplet barrier (Delta'/kB=7.25 K) and to the intermultiplet separation (Delta/kB=86.4 K) between S=5 andS=4.Pubblicazioni consigliate
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