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AbstractAbstract
[en] Published in summary form only
Original Title
Um modelo para vidros de Spin com Spins mistos
Primary Subject
Source
Almeida Fonseca, A.L. de (Brasilia Univ., DF (Brazil)); Koiler, B. (Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil)); Brescamsin, L.M. (Universidade Estadual de Campinas, SP (Brazil)) (and others); Sociedade Brasileira de Fisica, Rio de Janeiro, RJ (Brazil); 284 p; 1990; p. 91; 13. National Meeting on Condensed Matter Physics; Caxambu, MG (Brazil); 8-12 May 1990; Available from the Library of the Comissao Nacional de Energia Nuclear, RJ, Brazil
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AbstractAbstract
[en] In the infinite range spin glass model, we consider the staggered spin σsub(lambda)associated with a given eigenvector of the interaction matrix. We show that the thermal average of sub(lambda)sup(2) is a self-averaging quantity and we compute it
Record Type
Journal Article
Journal
Journal de Physique. Lettres; ISSN 0302-072X;
; v. 45(14); p. L.707-L.712

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Orland, Henri.
Paris-11 Univ., 91 - Orsay (France)1981
Paris-11 Univ., 91 - Orsay (France)1981
AbstractAbstract
[en] This work, in two parts, deals with the development of mean field theories in nuclear physics (nuclei in balance and collisions of heavy ions) as well as in disordered media. In the first part, two different ways of tackling the problem of developments around mean field theories are explained. Possessing an approach wave function for the system, the natural idea for including the correlations is to develop the exact wave function of the system around the mean field wave function. The first two chapters show two different ways of dealing with this problem: the perturbative approach - Hartree-Fock equations with two body collisions and functional methods. In the second part: mean field theory for spin glasses. The problem for spin glasses is to construct a physically acceptable mean field theory. The importance of this problem in statistical mechanics is linked to the fact that the mean field theory provides a qualitative description of the low temperature phase and is the starting point needed for using more sophisticated methods (renormalization group). Two approaches to this problem are presented, one based on the Sherrington-Kirkpatrick model and the other based on a model of spins with purely local disorder and competitive interaction between the spins
[fr]
Ce travail, compose de deux parties, traite des developpements des theories de champ moyen en physique nucleaire (noyaux a l'equilibre et collisions d'ions lourds) ainsi que dans les milieux desordonnes. Dans cette premiere partie, on expose deux facons, differentes dans l'esprit ainsi que dans les methodes, d'aborder le probleme des developpements autour des theories de champ moyen. Disposant d'une fonction d'onde approchee pour le systeme, l'idee naturelle pour inclure les correlations est de developper la fonction d'onde exacte du systeme autour de la fonction d'onde de champ moyen. Les chapitres 1 et 2 presentent deux manieres differentes de traiter ce probleme. 1) Approche perturbative: equations de Hartree-Fock avec collisions a deux corps. 2) Methodes fonctionnelles. Dans la 2eme partie: theorie de champ moyen pour les verres de spin, le probleme pour les verres de spin est de constuire une theorie de champ moyen physiquement acceptable. En mecanique statistique, l'importance de ce probleme est liee au fait que la theorie de champ moyen fournit une description qualitative de la phase de basse temperature, et est le point de depart necessaire a la mise en oeuvre de methodes plus sophistiquees (groupe de renormalisation). On presente deux approches a ce probleme, l'une fondee sur le modele de Sherrington-Kirkpatrick, et l'autre basee sur un modele de spin avec desordre purement local, et interaction competitive entre les spinsOriginal Title
Developpement des theories de champ moyen en physique nucleaire et dans les milieux desordonnes
Primary Subject
Source
Apr 1981; 245 p; These (D. es Sc.).
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Miscellaneous
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Thesis/Dissertation
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Fontanari, J.F.; Koeberle, R.
Proceedings of the 8. National Meeting of Particle Physics and Fields - Abstracts1987
Proceedings of the 8. National Meeting of Particle Physics and Fields - Abstracts1987
AbstractAbstract
[en] Published in summary form only
Original Title
Capacidade de memoria de redes de neuronios com interacao multispin
Source
Sociedade Brasileira de Fisica, Sao Paulo; 33 p; 1987; p. 25; 8. National Meeting of Particle Physics and Fields; Caxambu, MG (Brazil); 16-20 Sep 1987
Record Type
Miscellaneous
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Conference
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Borges, N.M.; Engelsberg, M.
Proceedings of the Latin American Symposium of Physics of Amorphous Systems- v.21984
Proceedings of the Latin American Symposium of Physics of Amorphous Systems- v.21984
AbstractAbstract
[en] The experimental results concerning Nuclear Magnetic Ressonance in B2O3 glasses are presented. The data analysis allows the study of the problem of spectral diffusion in a inhomogeneously enlarged resonance line in a disordered system of nuclear spins. It is proposed a model with the aim of explaining the observed time constants and the peculiar forms of decayment. (M.W.O.)
[pt]
Sao apresentados resultados experimentais sobre o decaimento de ecos estimulados de spin nuclear em vidros de B2O3. A analise dos dados permite estudar o problema de difusao espectral, numa linha de ressonancia magnetica nuclear inhomogeneamente alargada para um sistema desordenado de spins nucleares. E proposto um modelo para explicar as constantes de tempo observadas e a forma peculiar dos decaimentos. (M.W.O.)Original Title
Ecos de spin nuclear estimulados e difusao espectral em vidros
Source
Centro Latino Americano de Fisica, Rio de Janeiro (Brazil); Universidade Federal Fluminense, Niteroi (Brazil); 265 p; 1984; p. 468-477; Latin American Symposium of Physics of Amorphous Systems; Niteroi, RJ (Brazil); 27 Feb - 2 Mar 1984
Record Type
Miscellaneous
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Konior, J.; Longa, L.
International Centre for Theoretical Physics, Trieste (Italy)1980
International Centre for Theoretical Physics, Trieste (Italy)1980
AbstractAbstract
[en] The class of the models with periodically distributed frustration is solved exactly. The obtained thermodynamic properties of the models are similar to those observed in spin glasses and support the hypothesis of existence of the spin-glass phase in two dimensional, random Ising systems. (author)
Source
Jul 1980; 11 p
Record Type
Report
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Reference NumberReference Number
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Costa, F.A. de; Yokoi, C.S.O.; Salinas, S.R.
Proceedings of the 13. National Meeting on Condensed Matter1990
Proceedings of the 13. National Meeting on Condensed Matter1990
AbstractAbstract
[en] Published in summary form only
Original Title
Estudo da transicao de primeira ordem num modelo para vidros de spin
Source
Almeida Fonseca, A.L. de (Brasilia Univ., DF (Brazil)); Koiler, B. (Pontificia Univ. Catolica do Rio de Janeiro, RJ (Brazil)); Brescamsin, L.M. (Universidade Estadual de Campinas, SP (Brazil)) (and others); Sociedade Brasileira de Fisica, Rio de Janeiro, RJ (Brazil); 284 p; 1990; p. 77; 13. National Meeting on Condensed Matter Physics; Caxambu, MG (Brazil); 8-12 May 1990; Available from the Library of the Comissao Nacional de Energia Nuclear, RJ, Brazil
Record Type
Miscellaneous
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Conference
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Reference NumberReference Number
INIS VolumeINIS Volume
INIS IssueINIS Issue
AbstractAbstract
[en] We present a systematic small-correlation expansion to solve the inverse Ising problem and find a set of couplings and fields corresponding to a given set of correlations and magnetizations. Couplings are calculated up to the third order in the correlations for generic magnetizations and to the seventh order in the case of zero magnetizations; in addition, we show how to sum some useful classes of diagrams exactly. The resulting expansion outperforms existing algorithms on the Sherrington-Kirkpatrick spin-glass model
Primary Subject
Source
S1751-8113(09)93763-5; Available from http://dx.doi.org/10.1088/1751-8113/42/5/055001; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Physics. A, Mathematical and Theoretical (Online); ISSN 1751-8121;
; v. 42(5); [17 p.]

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Sherrington, David, E-mail: david.sherrington@physics.ox.ac.uk2019
AbstractAbstract
[en] Comparisons and analogies are drawn between materials ferroic glasses and conventional spin glasses, in terms of both experiment and theoretical modelling, with inter-system conceptual transfers leading to suggestions of further issues to investigate. (paper)
Primary Subject
Source
Available from http://dx.doi.org/10.1088/1751-8121/ab2166; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Physics. A, Mathematical and Theoretical (Online); ISSN 1751-8121;
; v. 52(26); [15 p.]

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Krishna Murthy, J.; Venimadhav, A., E-mail: venimadhav@hijli.iitkgp.ernet.in
arXiv e-print [ PDF ]2013
arXiv e-print [ PDF ]2013
AbstractAbstract
[en] We report a giant zero field cooled exchange bias (ZEB) effect (∼0.65 T) in La1.5Sr0.5CoMnO6 sample. Magnetic study has revealed a reentrant spin glass ∼90 K, phase separation to spin glass and ferromagnetic phases below 50 K and canted antiferromagnetic transition ∼10 K. A small conventional exchange bias (CEB) is established with the advent of spontaneous phase separation down to 10 K. Giant ZEB and enhanced CEB effects are found only below 10 K and are attributed to the large unidirectional anisotropy at the interface of isothermally field induced ferromagnetic phase and canted antiferromagnetic background
Primary Subject
Source
(c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
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