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Titolo:
Low-temperature specific heat of Fe-6 and Fe-10 molecular magnets
Autore:
Affronte, M; Lasjaunias, JC; Cornia, A; Caneschi, A;
Indirizzi:
Univ Modena, Ist Nazl Fis Mat, I-41100 Modena, Italy Univ Modena Modena Italy I-41100 Ist Nazl Fis Mat, I-41100 Modena, Italy Univ Modena, Dipartimento Fis, I-41100 Modena, Italy Univ Modena Modena Italy I-41100 Dipartimento Fis, I-41100 Modena, Italy CNRS, Ctr Rech Tres Basses Temp, F-38042 Grenoble, France CNRS Grenoble France F-38042 Tres Basses Temp, F-38042 Grenoble, France Univ Modena, Dipartimento Chim, I-41100 Modena, Italy Univ Modena ModenaItaly I-41100 ipartimento Chim, I-41100 Modena, Italy Univ Florence, Dipartimento Chim, I-50144 Florence, Italy Univ Florence Florence Italy I-50144 mento Chim, I-50144 Florence, Italy
Titolo Testata:
PHYSICAL REVIEW B-CONDENSED MATTER
fascicolo: 2, volume: 60, anno: 1999,
pagine: 1161 - 1166
SICI:
0163-1829(19990701)60:2<1161:LSHOFA>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
HIGH-SPIN MOLECULES; IRON(III) IONS; SINGLE-CRYSTAL; IRON CLUSTER; MAGNETIZATION; SUSCEPTIBILITY; RELAXATION; NANOMAGNET; DYNAMICS; COMPLEX;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
31
Recensione:
Indirizzi per estratti:
Indirizzo: Affronte, M Univ Modena, Ist Nazl Fis Mat, Via G Campi 213-A, I-41100 Modena, Italy Univ Modena Via G Campi 213-A Modena Italy I-41100 ena, Italy
Citazione:
M. Affronte et al., "Low-temperature specific heat of Fe-6 and Fe-10 molecular magnets", PHYS REV B, 60(2), 1999, pp. 1161-1166

Abstract

The energy splitting of the low-lying levels has been investigated on two magnetic molecular clusters Fe-6 and Fe-10 by means of low-temperature zero-field specific-heat measurements. Significant deviations from the usual C similar to T-2 law were observed above the maximum of the main Schottky anomalies as a result of nonnegligible contributions from the excited spin states with S>1 and the estimated lattice contributions follow a phenomenological power law C/R similar to T-alpha with alpha-2.7 for both these compounds. The singlet-triplet energy gaps evaluated by the Schottky anomaly, T-0=19.2 K for Fe6 and 4.56 K for Fe-10, are smaller than what we can estimate by a simplified spin-Hamiltonian approach in the strong exchange approximation and using the energy levels obtained by the high-field magnetization andsusceptibility measurements. This discrepancy asks for a more complex description of the low-lying states of these molecular clusters, beyond the strong exchange approximation. At very low temperatures T<<1 K, two low-energySchottky anomalies were also observed in Fe-10, probably due to a small fraction of defected rings or to hyperfine contributions.

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Documento generato il 12/07/20 alle ore 03:09:22