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Titolo:
Magnetic and structural properties of an octanuclear Cu(II) S=1/2 mesoscopic ring: Susceptibility and NMR measurements
Autore:
Lascialfari, A; Jang, ZH; Borsa, F; Gatteschi, D; Cornia, A; Rovai, D; Caneschi, A; Carretta, P;
Indirizzi:
Univ Pavia, Dept Phys A Volta, I-27100 Pavia, Italy Univ Pavia Pavia Italy I-27100 , Dept Phys A Volta, I-27100 Pavia, Italy Univ Pavia, Unita INFM, I-27100 Pavia, Italy Univ Pavia Pavia Italy I-27100 v Pavia, Unita INFM, I-27100 Pavia, Italy Iowa State Univ, Ames Lab, Ames, IA 50011 USA Iowa State Univ Ames IA USA50011 tate Univ, Ames Lab, Ames, IA 50011 USA Iowa State Univ, Dept Phys & Astron, Ames, IA 50011 USA Iowa State Univ Ames IA USA 50011 Dept Phys & Astron, Ames, IA 50011 USA Univ Florence, Dept Chem, I-50144 Florence, Italy Univ Florence FlorenceItaly I-50144 Dept Chem, I-50144 Florence, Italy Univ Modena, Dept Chem, I-41100 Modena, Italy Univ Modena Modena Italy I-41100 odena, Dept Chem, I-41100 Modena, Italy
Titolo Testata:
PHYSICAL REVIEW B
fascicolo: 10, volume: 61, anno: 2000,
pagine: 6839 - 6847
SICI:
1098-0121(20000301)61:10<6839:MASPOA>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURE; IRON(III) IONS; SPIN DYNAMICS; CLUSTERS; REACTIVITY; COMPLEXES; SPECTRA; H-1-NMR;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Lascialfari, A Univ Pavia, Dept Phys A Volta, Via Bassi 6, I-27100 Pavia, Italy Univ Pavia Via Bassi 6 Pavia Italy I-27100 00 Pavia, Italy
Citazione:
A. Lascialfari et al., "Magnetic and structural properties of an octanuclear Cu(II) S=1/2 mesoscopic ring: Susceptibility and NMR measurements", PHYS REV B, 61(10), 2000, pp. 6839-6847

Abstract

Magnetic susceptibility, H-1 NMR and Cu-63 NMR-NQR experiments on two slightly different species of the molecular S = 1/2 antiferromagnetic (AF) ringCu8, [Cu-8(dmpz)(8)(OH)(8)].2C(5)H(5)N (Cu8P) and [Cu-8(dmpz)(8)(OH)(8)].2C(5)H(5)NO(2) (Cu8N), are presented. The magnetic energy levels are calculated exactly for an isotropic Heisenberg model Hamiltonian in zero magnetic field. From the magnetic susceptibility measurements we estimate the AF exchange coupling constant J similar to 1000 K and the resulting gap Delta similar to 500 K between the S-T = 0 ground state and the S-T = 1 first excited state. The Cu-63,Cu-65 NQR spectra indicate the presence of four crystallographically inequivalent copper nuclei in each ring. From the combination of the Cu-63 NQR spectra and of the Cu-63 NMR spectra at high magnetic field, we estimate the quadrupole coupling constant nu(Q) of each site and the average asymmetry parameter eta of the electric-field gradient tensor. The nuclear spin-lattice relaxation rate (NSLR) decreases exponentially on decreasing temperature for all nuclei investigated. The gap parameter extractedfrom Cu-63 NQR-NSLR is the same as for the susceptibility while a smaller value is obtained from the Cu-63 NMR-NSLR in an external magnetic field of 8.2 T.

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Documento generato il 12/07/20 alle ore 02:04:12