Experimental characterization of the Ising model in disordered antiferromagnets

Belanger, D. P.

doi:10.1590/s0103-97332000000400009

Cited by 69 publications

(108 citation statements)

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“…24, 37, the pure Ising FP is unstable with a crossover exponent φ ≈ 0.11, which is substantially smaller than φ 4,4 at the O(5) FP. In these systems the asymptotic critical behavior has been precisely observed both numerically 38,39 and experimentally, 40 and sizeable crossover effects from the Ising to the random-exchange critical behavior have been observed also in the case of small dilution, without the need of reaching extremely small reduced-temperature values.…”

Section: Discussionmentioning

confidence: 78%

Instability of O(5) multicritical behavior in SO(5) theory of high-Tcsuperconductors

Hasenbusch

Pelissetto²,

Vicari

2005

Phys. Rev. B

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We study the nature of the multicritical point in the three-dimensional O(3)⊕O(2) symmetric Landau-Ginzburg-Wilson theory, which describes the competition of two order parameters that are O(3) and O(2) symmetric, respectively. This study is relevant for the SO(5) theory of high-T c superconductors, which predicts the existence of a multicritical point in the temperature-doping phase diagram, where the antiferromagnetic and superconducting transition lines meet.We investigate whether the O(3)⊕O( 2) symmetry gets effectively enlarged to O(5) approaching the multicritical point. For this purpose, we study the stability of the O(5) fixed point. By means of a Monte Carlo simulation, we show that the O(5) fixed point is unstable with respect to the spin-4 quartic perturbation with the crossover exponent φ 4,4 = 0.180(15), in substantial agreement with recent field-theoretical results. This estimate is much larger than the one-loop ǫ-expansion estimate φ 4,4 = 1/26, which has often been used in the literature to discuss the multicritical behavior within the SO(5) theory. Therefore, no symmetry enlargement is generically expected at the multicritical transition.We also perform a five-loop field-theoretical analysis of the renormalization-group flow. It shows that bicritical systems are not in the attraction domain of the stable decoupled fixed point. Thus, in these systems-high-T c cuprates should belong to this class-the multicritical point corresponds to a first-order transition.

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Section: Discussionmentioning

confidence: 78%

Instability of O(5) multicritical behavior in SO(5) theory of high-Tcsuperconductors

Hasenbusch

Pelissetto²,

Vicari

2005

Phys. Rev. B

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“…A simple and natural case of disorder is implemented via the point-like uncorrelated quenched nonmagnetic impurities and is experimentally realized as substitutional disorder in uniaxial [1] as well as in Heisenberg [2,3] magnets. Examples are given by substitute alloys Mn x Zn 1−x F 2 , Fe x Zn 1−x F 2 for the uniaxial (Ising) magnets [4], and by amorphous magnets Fe 90+x Zr 10−x , Fe 90−y M y Zr 10 ( M = Co, Mn, Ni) [5,6], transition-metal based magnetic glasses [7,8] as well as disordered crystalline materials Fe 100−x Pt x [9], Fe 70 Ni 30 [8] and Euchalcogenide solid solutions [10] for the Heisenberg magnets. The question of a great interest arising here is: does the disorder change critical properties of the systems?…”

Section: Introductionmentioning

confidence: 99%

Critical dynamics and effective exponents of magnets with extended impurities

et al. 2005

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We investigate the asymptotic and effective static and dynamic critical behavior of (d = 3)-dimensional magnets with quenched extended defects, correlated in ε d dimensions (which can be considered as the dimensionality of the defects) and randomly distributed in the remaining d − ε d dimensions. The field-theoretical renormalization group perturbative expansions being evaluated naively do not allow for the reliable numerical data. We apply the Chisholm-Borel resummation technique to restore convergence of the two-loop expansions and report the numerical values of the asymptotic critical exponents for the model A dynamics. We discuss different scenarios for static and dynamic effective critical behavior and give values for corresponding non-universal exponents.

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“…Fig. 5 shows the maximum of the specific heat C max as a function of L. Least-squares fits to a logarithmic Ansatz C max = B 0 + B 1 ln L give B 0 = 0.44(6), B 1 = 0.72 (1) and is shown by the full line in Fig. 5.…”

Section: Results and Conclusionmentioning

confidence: 98%

“…Experimental studies of the critical behavior of real materials are often confronted with the influence of impurities and inhomogeneities [1]. For a proper interpretation of the measurements it is, therefore, important to develop a firm theoretical understanding of the effect of such random perturbations.…”

Section: Introductionmentioning

confidence: 99%

Critical behavior of the spin-3/2 Blume-Capel model on a random two-dimensional lattice

Lima¹,

Plascak²

2006

Braz. J. Phys.

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We investigate the critical properties of the spin-3/2 Blume-Capel model in two dimensions on a random lattice with quenched connectivity disorder. The disordered system is simulated by applying the cluster hybrid Monte Carlo update algorithm and re-weighting techniques. We calculate the critical temperature as well as the critical point exponents γ/ν, β/ν, α/ν, and ν. We find that, contrary of what happens to the spin-1/2 case, this random system does not belong to the same universality class as the regular two-dimensional ferromagnetic model.

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Experimental characterization of the Ising model in disordered antiferromagnets

Cited by 69 publications

References 0 publications

Instability of O(5) multicritical behavior in SO(5) theory of high-Tcsuperconductors

Instability of O(5) multicritical behavior in SO(5) theory of high-Tcsuperconductors

Critical dynamics and effective exponents of magnets with extended impurities

Critical behavior of the spin-3/2 Blume-Capel model on a random two-dimensional lattice

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