We present muon spin relaxation and 1H NMR results on the magnetically frustrated keplerate molecule Mo72Fe30, aimed at studying the local spin dynamics as a function of temperature. We find that, in common with other molecular magnets, the relaxation spectrum of this material is characterized by a single dominating electronic correlation time t. Experiments and theory show that t has a thermally activated behavior with an activation gap of the order of the energy difference between the lowest-lying rotational bands in this material. This shows that, in the intermediate temperature range just above 1 K, the relaxation of the electronic spin system occurs via Orbach processes involving energy levels belonging to the two lowest-lying rotational bands. Our data thus provide an experimental estimate of the first interband gap.

Low-energy spin dynamics in the giant keplerate molecule Mo72Fe30: A muon spin relaxation and 1H NMR investigation

MICOTTI, EDOARDO;CORTI, MAURIZIO ENRICO;LASCIALFARI, ALESSANDRO;
2007

Abstract

We present muon spin relaxation and 1H NMR results on the magnetically frustrated keplerate molecule Mo72Fe30, aimed at studying the local spin dynamics as a function of temperature. We find that, in common with other molecular magnets, the relaxation spectrum of this material is characterized by a single dominating electronic correlation time t. Experiments and theory show that t has a thermally activated behavior with an activation gap of the order of the energy difference between the lowest-lying rotational bands in this material. This shows that, in the intermediate temperature range just above 1 K, the relaxation of the electronic spin system occurs via Orbach processes involving energy levels belonging to the two lowest-lying rotational bands. Our data thus provide an experimental estimate of the first interband gap.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11571/105187
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