Theory and computer simulation of diffuse scattering from lattice-gas models: Structure-factor calculations for the high-temperature superconductorYBa2Cu<

Mean-field and Monte Carlo calculations of the three-dimensional structure factor forYBa2Cu3Fiig1, Andersen2, Lindgård3 et al. 1996Phys. Rev. BSelf Cite8071View full textAdd to dashboardCite

“…8 Also the line shape changes radically to a Lorentzian shape also below T c in contrast to the 2D results. 54 The behavior of the correlation length is found to follow that of the 2D and 3D Ising models, with exponents consistent with the Ising universality classes. The anisotropy in the correlation lengths is found to be independent of D and of x.…”

“…This case was discussed by Fiig et al 54 The Fourier transforms of the phase and the antiphase are the same and the total S dif tot (q)ϭb 2 ͉F(q)͉ 2 ϭ2͓1Ϫcos(qa)͔S dif (q) is modulated with twice the period of the ortho-II S dif (q). However, diffuse scattering for a domain of size l 0 and a lattice constant a is given by S dif (q)ϰsin 2 (ql 0 a/2)/sin 2 (qa/2), where q is measured from the ortho-II peaks.…”

Oxygen-ordering superstructures in underdopedYBa2Cu3O6Zimmermann1, Schneider2, Frello3 et al. 2003Phys. Rev. BSelf Cite815740View full textAdd to dashboardCite

“…Here it is interesting to note that our data show that the ratios of the correlation lengths are essentially independent of the oxygen stoichiometry in the ortho-II and the ortho-III phases. A comparison between this result and mean field predictions of the peak widths 40 indicates that the ASYNNNI model interaction parameters are independent of x. This assumption has been a major objection against the validity of the ASYNNNI model.…”

Analytical Theory of Diffuse Scattering from Distributions of Non-overlapping Structures

“…It is important to go beyond, for example, the oftenused simple Warren approximation (Warren, 1941(Warren, , 1990 in describing scattering from variously sized objects in order to obtain their statistical size distributions. In a recent paper (Fiig, Andersen, Berlin & Lindg~d, 1995) (note that in Table I therein, ~; only refers to the half-width, not the FWHM), the diffuse scattering was discussed in terms of distribution probabilities of sizes for the various scattering objects, while neglecting the distribution of the space between the objects. We shall extend this work considerably by first considering the distributions of all the space-filling objects.…”

“…We shall only consider the diffuse scattering as arising from breaking a perfect order of a lattice gas system. The general scattering theory was introduced by Fiig et al (1995) in some detail and will not be repeated here. The exact results for the cross section will be given for the linear chain and the possible extrapolation of the results to higher dimensions will also be discussed.…”