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Titolo:
Quantum effects in magnetic structures on the fcc lattice
Autore:
Lefmann, K; Rischel, C;
Indirizzi:
Riso Natl Lab, Condensed Matter Phys & Chem Dept, DK-4000 Roskilde, Denmark Riso Natl Lab Roskilde Denmark DK-4000 m Dept, DK-4000 Roskilde, Denmark Royal Vet & Agr Univ, Dept Math & Phys, DK-1871 Frederiksberg C, Denmark Royal Vet & Agr Univ Frederiksberg Denmark C 71 Frederiksberg C, Denmark Univ Copenhagen, Niels Bohr Inst, DK-2100 Copenhagen O, Denmark Univ Copenhagen Copenhagen Denmark O Inst, DK-2100 Copenhagen O, Denmark
Titolo Testata:
EUROPEAN PHYSICAL JOURNAL B
fascicolo: 3, volume: 21, anno: 2001,
pagine: 313 - 329
SICI:
1434-6028(200106)21:3<313:QEIMSO>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
NEGATIVE NANOKELVIN TEMPERATURES; EXACT DIAGONALIZATION; CUBIC LATTICES; GROUND-STATE; ANTIFERROMAGNETS; MODELS; ZERO; SELECTION; DISORDER; SILVER;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
43
Recensione:
Indirizzi per estratti:
Indirizzo: Lefmann, K Riso Natl Lab, Condensed Matter Phys & Chem Dept, DK-4000 Roskilde, Denmark Riso Natl Lab Roskilde Denmark DK-4000 4000 Roskilde, Denmark
Citazione:
K. Lefmann e C. Rischel, "Quantum effects in magnetic structures on the fcc lattice", EUR PHY J B, 21(3), 2001, pp. 313-329

Abstract

We present the results of a numerical diagonalization study of the next-nearest neighbour Heisenberg model on the fee lattice. We have studied clusters of s = 1/2 spins of sizes N = 32 and 64 and obtained ground state energy, magnetization, susceptibility, and static structure factor for various values of applied fields and interaction parameters. From the magnetic structure factors, we find that the antiferromagnetic type-II order penetrates into the ferromagnetic area of the mean-held model. The magnetisation of the type-II state in this area jumps from zero to totally magnetised at a certain applied field. Other areas containing type-II or type-III order, displays "offsets" in the magnetisation curves. Another anomaly is that the phase boundary between the type-I and the type-III states moves in favour of the type-I state around half magnetisation. Apart from this, the phase boundaries are located at their mean field values at zero field, and the positions of the phase boundaries do not depend on the field value. By comparing the longitudinal and transverse structure factors, it is found that the spin orientation in the type-I structure at intermediate fields shows a transitionbetween a canted spin-flop-like structure and a collinear "up-up-up-down" structure. This confirms earlier theoretical predictions. However, in the type-II and type-III phases only the spin-flop structures are observed.

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Documento generato il 01/04/20 alle ore 19:13:31