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.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Sep 29 2009|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics