Magnetic chains of Fe3 clusters in the {Fe3YO2} butterfly molecular compound

The “butterfly” molecule [Fe3Y(μ3-O)2(CCl3COO)8(H2O)(THF)3] (in brief {Fe3YO2}) includes three Fe3+ ions which build a robust Fe3 cluster with a strong intracluster antiferromagnetic exchange [Formula Omitted] and a total spin S = 5/2. It represents the starting magnetic system to study further inte...

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Veröffentlicht in:Dalton transactions : an international journal of inorganic chemistry 2020-03, Vol.49 (9), p.2979-2988
Hauptverfasser: Rubín, Javier, Badía-Romano, Laura, Fernando, Luis, Mereacre, Valeriu, Prodius, Denis, Arauzo, Ana, Bartolomé, Fernando, Bartolomé, Juan
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Sprache:eng
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Zusammenfassung:The “butterfly” molecule [Fe3Y(μ3-O)2(CCl3COO)8(H2O)(THF)3] (in brief {Fe3YO2}) includes three Fe3+ ions which build a robust Fe3 cluster with a strong intracluster antiferromagnetic exchange [Formula Omitted] and a total spin S = 5/2. It represents the starting magnetic system to study further interactions with magnetic rare earths when Y is replaced with lanthanides. We present heat capacity and equilibrium susceptibility measurements below 2 K, which show that each cluster has a sizeable magnetic anisotropy pointing to the existence of intercluster interactions. However, no phase transition to a long-range magnetically ordered phase is observed down to 20 mK. The intercluster interaction is analysed in the framework of the one-dimensional Blume–Capel model with an antiferromagnetic chain interaction constant J/kB = −40(2) mK between Fe3 cluster spins, and a uniaxial anisotropy with parameter D/kB = −0.56(3) K. This is associated to single chains of Fe3 clusters oriented along the shortest intercluster distances displayed by the crystal structure of {Fe3YO2}. Ac susceptibility measurements reveal that the magnetic relaxation is dominated by a quantum tunnelling process below 0.2 K, and by thermally activated processes above this temperature. The experimental activation energy of this single chain magnet, Ea/kB = 3.4(6) K, can be accounted for by the combination of contributions arising from single-molecule magnetic anisotropy and spin–spin correlations along the chains.
ISSN:1477-9226
1477-9234
DOI:10.1039/c9dt04816b