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

TitleLow-energy spin dynamics in the giant keplerate molecule {Mo72Fe30}: A muon spin relaxation and H-1 NMR investigation
Publication TypeJournal Article
Year of Publication2007
AuthorsLago J, Micotti E, Corti M, Lascialfari A, Bianchi A, Carretta S, Santini P, Procissi D, Baek SH, Kogerler P, Baines C, Amato A
Journal TitlePhysical Review B
Volume76
Pages064432
Date PublishedAug
Type of ArticleArticle
ISBN Number1098-0121
Accession NumberISI:000249155200085
Keywordsclusters, MOLYBDENUM-OXIDE, NUCLEAR MAGNETIC RELAXATION, PROTON NMR, spheres, systems
Abstract

We present muon spin relaxation and H-1 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 tau. Experiments and theory show that tau 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.

DOI10.1103/PhysRevB.76.064432
Alternate JournalPhys. Rev. B