The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform
A. Nihat Berker - One of the best experts on this subject based on the ideXlab platform.
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Chiral Potts Spin Glass in d=2 and 3 dimensions.
Physical Review E, 2016Co-Authors: Tolga Çağlar, A. Nihat BerkerAbstract:The chiral Spin-Glass Potts system with q = 3 states is studied in d = 2 and 3 spatial dimensions by renormalization-group theory and the global phase diagrams are calculated in temperature, chirality concentration p, and chirality-breaking concentration c, with determination of phase chaos and phase-boundary chaos. In d = 3, the system has ferromagnetic, left-chiral, right-chiral, chiral Spin-Glass, and disordered phases. The phase boundaries to the ferromagnetic, left-and right-chiral phases show, differently, an unusual, fibrous patchwork (microreentrances) of all four (ferromagnetic, left-chiral, right-chiral, chiral Spin-Glass) ordered phases, especially in the multicritical region. The chaotic behavior of the interactions, under scale change, are determined in the chiral Spin-Glass phase and on the boundary between the chiral Spin-Glass and disordered phases, showing Lyapunov exponents in magnitudes reversed from the usual ferromagnetic-antiferromagnetic Spin-Glass systems. At low temperatures, the boundaries of the left-and right-chiral phases become thresholded in p and c. In d = 2, the chiral Spin-Glass Potts system does not have a Spin-Glass phase, consistently with the lower-critical dimension of ferromagnetic-antiferromagnetic Spin Glasses. The left-and right-chirally ordered phases show reentrance in chirality concentration p
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Quenched-vacancy induced Spin-Glass order.
Physical Review E, 2009Co-Authors: Gul Gulpinar, A. Nihat BerkerAbstract:The ferromagnetic phase of an Ising model in d=3, with any amount of quenched antiferromagnetic bond randomness, is shown to undergo a transition to a Spin-Glass phase under sufficient quenched bond dilution. This result, demonstrated here with the numerically exact global renormalization-group solution of a d=3 hierarchical lattice, is expected to hold true generally, for the cubic lattice and for quenched site dilution. Conversely, in the ferromagnetic–Spin-Glass–antiferromagnetic phase diagram, the Spin-Glass phase expands under quenched dilution at the expense of the ferromagnetic and antiferromagnetic phases. In the ferromagnetic–Spin-Glass phase transition induced by quenched dilution, reentrance as a function of temperature is seen, as previously found in the ferromagnetic–Spin-Glass transition induced by increasing the antiferromagnetic bond concentration.Scientific and Technological Research Council of Turkey (TÜBİTAK
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Quenched-vacancy induced Spin-Glass order.
Physical review. E Statistical nonlinear and soft matter physics, 2009Co-Authors: Gul Gulpinar, A. Nihat BerkerAbstract:The ferromagnetic phase of an Ising model in d=3 , with any amount of quenched antiferromagnetic bond randomness, is shown to undergo a transition to a Spin-Glass phase under sufficient quenched bond dilution. This result, demonstrated here with the numerically exact global renormalization-group solution of a d=3 hierarchical lattice, is expected to hold true generally, for the cubic lattice and for quenched site dilution. Conversely, in the ferromagnetic-Spin-Glass-antiferromagnetic phase diagram, the Spin-Glass phase expands under quenched dilution at the expense of the ferromagnetic and antiferromagnetic phases. In the ferromagnetic-Spin-Glass phase transition induced by quenched dilution, reentrance as a function of temperature is seen, as previously found in the ferromagnetic-Spin-Glass transition induced by increasing the antiferromagnetic bond concentration.
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Blume-Emery-Griffiths Spin Glass and inverted tricritical points
Physical Review E, 2008Co-Authors: V. Ongun Özçelik, A. Nihat BerkerAbstract:The Blume-Emery-Griffiths Spin Glass is studied by renormalization-group theory in d=3 . The boundary between the ferromagnetic and paramagnetic phases has first-order and two types of second-order segments. This topology includes an inverted tricritical point, first-order transitions replacing second-order transitions as temperature is lowered. The phase diagrams show disconnected Spin-Glass regions, Spin-Glass and paramagnetic reentrances, and complete reentrance, where the Spin-Glass phase replaces the ferromagnet as temperature is lowered for all chemical potentials.
Gul Gulpinar - One of the best experts on this subject based on the ideXlab platform.
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Quenched-vacancy induced Spin-Glass order.
Physical Review E, 2009Co-Authors: Gul Gulpinar, A. Nihat BerkerAbstract:The ferromagnetic phase of an Ising model in d=3, with any amount of quenched antiferromagnetic bond randomness, is shown to undergo a transition to a Spin-Glass phase under sufficient quenched bond dilution. This result, demonstrated here with the numerically exact global renormalization-group solution of a d=3 hierarchical lattice, is expected to hold true generally, for the cubic lattice and for quenched site dilution. Conversely, in the ferromagnetic–Spin-Glass–antiferromagnetic phase diagram, the Spin-Glass phase expands under quenched dilution at the expense of the ferromagnetic and antiferromagnetic phases. In the ferromagnetic–Spin-Glass phase transition induced by quenched dilution, reentrance as a function of temperature is seen, as previously found in the ferromagnetic–Spin-Glass transition induced by increasing the antiferromagnetic bond concentration.Scientific and Technological Research Council of Turkey (TÜBİTAK
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Quenched-vacancy induced Spin-Glass order.
Physical review. E Statistical nonlinear and soft matter physics, 2009Co-Authors: Gul Gulpinar, A. Nihat BerkerAbstract:The ferromagnetic phase of an Ising model in d=3 , with any amount of quenched antiferromagnetic bond randomness, is shown to undergo a transition to a Spin-Glass phase under sufficient quenched bond dilution. This result, demonstrated here with the numerically exact global renormalization-group solution of a d=3 hierarchical lattice, is expected to hold true generally, for the cubic lattice and for quenched site dilution. Conversely, in the ferromagnetic-Spin-Glass-antiferromagnetic phase diagram, the Spin-Glass phase expands under quenched dilution at the expense of the ferromagnetic and antiferromagnetic phases. In the ferromagnetic-Spin-Glass phase transition induced by quenched dilution, reentrance as a function of temperature is seen, as previously found in the ferromagnetic-Spin-Glass transition induced by increasing the antiferromagnetic bond concentration.
Giorgio Parisi - One of the best experts on this subject based on the ideXlab platform.
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Overlap Interfaces in Hierarchical Spin-Glass models
Journal of Statistical Mechanics: Theory and Experiment, 2008Co-Authors: Silvio Franz, T Jorg, Giorgio ParisiAbstract:We discuss interfaces in Spin Glasses. We present new theoretical results and a numerical method to characterize overlap interfaces and the stability of the Spin-Glass phase in extended disordered systems. We use this definition to characterize the low temperature phase of hierarchical Spin-Glass models. We use the Replica Symmetry Breaking theory to evaluate the cost for an overlap interface, which in these models is particularly simple. A comparison of our results from numerical simulations with the theoretical predictions shows good agreement.
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Zero-Temperature Responses of a 3D Spin Glass in a Magnetic Field
Physical review letters, 2001Co-Authors: Florent Krzakala, Enzo Marinari, J. Houdayer, Olivier Martin, Giorgio ParisiAbstract:We probe the energy landscape of the 3D Edwards-Anderson Spin Glass in a magnetic field to test for a Spin Glass ordering. We find that the Spin Glass susceptibility is anomalously large on the lattice sizes we can reach. Our data suggest that a transition from the Spin Glass to the paramagnetic phase takes place at B(c) approximately 0.65, though the possibility B(c) = 0 cannot be excluded. We also discuss the question of the nature of the putative frozen phase.
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The Bethe lattice Spin Glass revisited
The European Physical Journal B, 2001Co-Authors: Marc Mézard, Giorgio ParisiAbstract:So far the problem of a Spin Glass on a Bethe lattice has been solved only at the replica symmetric level, which is wrong in the Spin Glass phase. Because of some technical difficulties, attempts at deriving a replica symmetry breaking solution have been confined to some perturbative regimes, high connectivity lattices or temperature close to the critical temperature. Using the cavity method, we propose a general non perturbative solution of the Bethe lattice Spin Glass problem at a level of approximation which is equivalent to a one step replica symmetry breaking solution. The results compare well with numerical simulations. The method can be used for many finite connectivity problems appearing in combinatorial optimization.
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Zero-temperature responses of a 3D Spin Glass in a magnetic field
Physical Review Letters, 2001Co-Authors: Florent Krzakala, Enzo Marinari, J. Houdayer, Olivier Martin, Giorgio ParisiAbstract:We probe the energy landscape of the 3D Edwards-Anderson Spin Glass in a magnetic field to test for a Spin Glass ordering. We find that the Spin Glass susceptibility is anomalously large on the lattice sizes we can reach. Our data suggest that a transition from the Spin Glass to the paramagnetic phase takes place at B_c=0.65, though the possibility B_c=0 cannot be excluded. We also discuss the question of the nature of the putative frozen phase.
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Four-dimensional Ising Spin Glass: scaling within the Spin-Glass phase
Journal of Physics A: Mathematical and General, 1993Co-Authors: J.c. Ciria, Giorgio Parisi, Felix RitortAbstract:We investigate the nature of the Spin-Glass phase in the four-dimensional king Spin Glass. We study he probability dishibutions of overlaps, of energy overlaps and ullrmetricity for several sizes. We discover the existence of finite-size scaling in the fails of the first and second of these. This allows us to exmct mame exponents within the Spin-Glass phase. We also perform studies on quenched thermalization of large samples. Our results together with previous work favour the mean-field picfure of the Spin-Glass phase.
Florent Krzakala - One of the best experts on this subject based on the ideXlab platform.
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elusive Spin Glass phase in the random field ising model
Physical Review Letters, 2010Co-Authors: Florent Krzakala, Federico Riccitersenghi, Lenka ZdeborovaAbstract:: We show rigorously that the Spin-Glass susceptibility in the random field Ising model is always bounded by the ferromagnetic susceptibility, and therefore that no Spin-Glass phase can be present at equilibrium out of the ferromagnetic critical line. When the magnetization is, however, fixed to values smaller than the equilibrium value, a Spin-Glass phase can exist, as we show explicitly on the Bethe lattice.
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Zero-Temperature Responses of a 3D Spin Glass in a Magnetic Field
Physical review letters, 2001Co-Authors: Florent Krzakala, Enzo Marinari, J. Houdayer, Olivier Martin, Giorgio ParisiAbstract:We probe the energy landscape of the 3D Edwards-Anderson Spin Glass in a magnetic field to test for a Spin Glass ordering. We find that the Spin Glass susceptibility is anomalously large on the lattice sizes we can reach. Our data suggest that a transition from the Spin Glass to the paramagnetic phase takes place at B(c) approximately 0.65, though the possibility B(c) = 0 cannot be excluded. We also discuss the question of the nature of the putative frozen phase.
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Zero-temperature responses of a 3D Spin Glass in a magnetic field
Physical Review Letters, 2001Co-Authors: Florent Krzakala, Enzo Marinari, J. Houdayer, Olivier Martin, Giorgio ParisiAbstract:We probe the energy landscape of the 3D Edwards-Anderson Spin Glass in a magnetic field to test for a Spin Glass ordering. We find that the Spin Glass susceptibility is anomalously large on the lattice sizes we can reach. Our data suggest that a transition from the Spin Glass to the paramagnetic phase takes place at B_c=0.65, though the possibility B_c=0 cannot be excluded. We also discuss the question of the nature of the putative frozen phase.
Hikaru Kawamura - One of the best experts on this subject based on the ideXlab platform.
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Ordering of the Heisenberg Spin Glass in four dimensions
Physical Review B, 2012Co-Authors: Hikaru Kawamura, Shinichirou NishikawaAbstract:Ordering of the Heisenberg Spin Glass in four dimensions (4D) with the nearest-neighbor Gaussian coupling is investigated by equilibrium Monte Carlo simulations, with particular attention to its Spin and chiral orderings. It is found that the Spin and the chirality order simultaneously with a common correlation-length exponent $\nu_{CG}=\nu_{SG}\simeq 1.0$, i.e., the absence of the Spin-chirality decoupling in 4D. Yet, the Spin-Glass ordered state exhibits a nontrivial phase-space structure associated with a continuous one-step-like replica-symmetry breaking, different in nature from that of the Ising Spin Glass or of the mean-field Spin Glass. Comparison is made with the ordering of the Heisenberg Spin Glass in 3D, and with that of the 1D Heisenberg Spin Glass with a long-range power-law interaction. It is argued that the 4D might be close to the marginal dimension separating the Spin-chirality decoupling/coupling regimes.Comment: to appear in Phys. Rev.
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Chirality Scenario of the Spin-Glass Ordering
Journal of the Physical Society of Japan, 2010Co-Authors: Hikaru KawamuraAbstract:Detailed account is given of the chirality scenario of experimental Spin-Glass transitions. In this scenario, the Spin Glass order of weakly anisotropic Heisenberg-like Spin-Glass magnets including canonical Spin Glasses are essentially chirality driven. Recent numerical and experimental results are discussed in conjunction with this scenario.
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Ordering of the Heisenberg Spin Glass in high dimensions
Physical Review B, 2003Co-Authors: Daisuke Imagawa, Hikaru KawamuraAbstract:Ordering of the Heisenberg Spin Glass with the nearest-neighbor Gaussian coupling is investigated by equilibrium Monte Carlo simulations in four and five dimensions. Ordering of the mean-field Heisenberg Spin-Glass is also studied for comparison. Particular attention is paid to the nature of the Spin-Glass and the chiral-Glass orderings. Our numerical data suggest that, in five dimensions, the model exhibits a single Spin-Glass transition at a finite temperature, where the Spin-Glass order accompanying the simultaneous chiral-Glass order sets in. In four dimensions, by contrast, the model exhibits a chiral-Glass transition at a finite temperature, not accompanying the standard Spin-Glass order. The critical region associated with the chiral-Glass transition, however, is very narrow, suggesting that dimension four is close to the marginal dimensionality.Comment: 18 pages, 12 figure
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Fluctuation-dissipation ratio of the Heisenberg Spin Glass.
Physical review letters, 2003Co-Authors: Hikaru KawamuraAbstract:The fluctuation-dissipation (FD) relation of the three-dimensional Heisenberg Spin Glass with weak random anisotropy is studied by off-equilibrium Monte Carlo simulation. The numerically determined FD ratio exhibits a "one-step-like" behavior, the effective temperature of the Spin-Glass state being about twice the Spin-Glass transition temperature, T(eff) approximately 2T(g), irrespective of the bath temperature. The results are discussed in conjunction with the recent experiment by Hérisson and Ocio, and with the chirality scenario of the Spin-Glass transition.
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Dynamical aspects of a three-dimensional Heisenberg Spin Glass
arXiv: Disordered Systems and Neural Networks, 2000Co-Authors: Hikaru Kawamura, Koji HukushimaAbstract:Spin-Glass and chiral-Glass orderings of a three-dimensional isotropic Heisenberg Spin Glass are studied both by equilibrium and off-equilibrium Monte Carlo simulations with emphasis on their dynamical aspects. The model is found to exhibit a finite-temperature chiral-Glass transition without the conventional Spin-Glass order. Although chirality is an Ising-like quantity from symmetry, universality class of the chiral-Glass transition appears to be different from that of the standard Ising Spin Glass. In the off-equilibrium simulation, while the Spin autocorrelation exhibits only an interrupted aging, the chirality autocorrelation persists to exhibit a pronounced aging effect reminiscent of the one observered in the mean-field model.
