69,71 Ga NMR studies of a superconducting Ga 84 cluster compound
| Autor: | N. Zelders, Andreas Schnepf, L. Jos de Jongh, H. B. Brom, Hansgeorg Schnöckel, O. N. Bakharev |
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| Rok vydání: | 2003 |
| Předmět: | |
| Zdroj: | The European Physical Journal D - Atomic, Molecular and Optical Physics. 24:101-104 |
| ISSN: | 1434-6079 1434-6060 |
| DOI: | 10.1140/epjd/e2003-00147-0 |
| Popis: | We present 69,71Ga-NMR experiments on microcrystalline samples of the recently discovered supramolecular compound Ga 84 [ N ( SiMe 3 ) 2 ] 20 Li 6 Br 2 ( thf ) 20 . 2 toluene, which is composed of ligand-coordinated Ga84 metal clusters, packed together in a fully ordered crystalline matrix. The compound is highly conducting and even shows superconductivity below T c ~ 7.2 K. Our preliminary results between 10-300 K show a metallic-like behavior: the nuclear spin-lattice relaxation rate T 1 -1 follows the Korringa law 69 ( T 1 T ) -1 = 0.36 s -1 K -1 , but with a relaxation rate approximately three times smaller than in bulk α-Ga metal. No quantum-size effects are observed, the Korringa law being followed down to 10 K, whereas the quantum-gaps for individual clusters should amount to ~ 10 3 K. These results therefore suggest a transport process based on intermolecular charge transfer, similar as in alkali-doped fullerenes and silicon-clathrates. |
| Databáze: | OpenAIRE |
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