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;
2007-01-01
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
