92 research outputs found

    Probability distribution of the conductance at the mobility edge

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    Distribution of the conductance P(g) at the critical point of the metal-insulator transition is presented for three and four dimensional orthogonal systems. The form of the distribution is discussed. Dimension dependence of P(g) is proven. The limiting cases gg\to\infty and g0g\to 0 are discussed in detail and relation P(g)0P(g)\to 0 in the limit g0g\to 0 is proven.Comment: 4 pages, 3 .eps figure

    Comment on the paper I. M. Suslov: Finite Size Scaling from the Self Consistent Theory of Localization

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    In the recent paper [I.M.Suslov, JETP {\bf 114} (2012) 107] a new scaling theory of electron localization was proposed. We show that numerical data for the quasi-one dimensional Anderson model do not support predictions of this theory.Comment: Comment on the paper arXiv 1104.043

    Symmetry, dimension and the distribution of the conductance at the mobility edge

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    The probability distribution of the conductance at the mobility edge, pc(g)p_c(g), in different universality classes and dimensions is investigated numerically for a variety of random systems. It is shown that pc(g)p_c(g) is universal for systems of given symmetry, dimensionality, and boundary conditions. An analytical form of pc(g)p_c(g) for small values of gg is discussed and agreement with numerical data is observed. For g>1g > 1, lnpc(g)\ln p_c(g) is proportional to (g1)(g-1) rather than (g1)2(g-1)^2.Comment: 4 pages REVTeX, 5 figures and 2 tables include

    Electronic transport in strongly anisotropic disordered systems: model for the random matrix theory with non-integer beta

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    We study numerically an electronic transport in strongly anisotropic weakly disorderd two-dimensional systems. We find that the conductance distribution is gaussian but the conductance fluctuations increase when anisotropy becomes stronger. We interpret this result by random matrix theory with non-integer symmetry parameter beta, in accordance with recent theoretical work of K.A.Muttalib and J.R.Klauder [Phys.Rev.Lett. 82 (1999) 4272]. Analysis of the statistics of transport paramateres supports this hypothesis.Comment: 8 pages, 7 *.eps figure

    Character of eigenstates of the 3D disordered Anderson Hamiltonian

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    We study numerically the character of electron eigenstates of the three dimensional disordered Anderson model. Analysis of the statistics of inverse participation ratio as well as numerical evaluation of the electron-hole correlation function confirm that there are no localized states below the mobility edge, as well as no metallic state in the tail of the conductive band. We discuss also finite size effects observed in the analysis of all the discussed quantities.Comment: 7 pages, 9 figures, resubmitted to Physical Review

    Localization Transition in Multilayered Disordered Systems

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    The Anderson delocalization-localization transition is studied in multilayered systems with randomly placed interlayer bonds of density pp and strength tt. In the absence of diagonal disorder (W=0), following an appropriate perturbation expansion, we estimate the mean free paths in the main directions and verify by scaling of the conductance that the states remain extended for any finite pp, despite the interlayer disorder. In the presence of additional diagonal disorder (W>0W > 0) we obtain an Anderson transition with critical disorder WcW_c and localization length exponent ν\nu independently of the direction. The critical conductance distribution Pc(g)P_{c}(g) varies, however, for the parallel and the perpendicular directions. The results are discussed in connection to disordered anisotropic materials.Comment: 10 pages, Revtex file, 8 postscript files, minor change

    Determination of Effective Permittivity and Permeability of Metamaterials from Reflection and Transmission Coefficients

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    We analyze the reflection and transmission coefficients calculated from transfer matrix simulations on finite lenghts of electromagnetic metamaterials, to determine the effective permittivity and permeability. We perform this analysis on structures composed of periodic arrangements of wires, split ring resonators (SRRs) and both wires and SRRs. We find the recovered frequency-dependent permittivity and permeability are entirely consistent with analytic expressions predicted by effective medium arguments. Of particular relevance are that a wire medium exhibits a frequency region in which the real part of permittivity is negative, and SRRs produce a frequency region in which the real part of permeability is negative. In the combination structure, at frequencies where both the recovered real part of permittivity and permeability are simultaneously negative, the real part of the index-of-refraction is found also to be unambigously negative.Comment: *.pdf file, 5 figure

    Universality of the critical conductance distribution in various dimensions

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    We study numerically the metal - insulator transition in the Anderson model on various lattices with dimension 2<d42 < d \le 4 (bifractals and Euclidian lattices). The critical exponent ν\nu and the critical conductance distribution are calculated. We confirm that ν\nu depends only on the {\it spectral} dimension. The other parameters - critical disorder, critical conductance distribution and conductance cummulants - depend also on lattice topology. Thus only qualitative comparison with theoretical formulae for dimension dependence of the cummulants is possible

    Scaling of the conductance distribution near the Anderson transition

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    The single parameter scaling hypothesis is the foundation of our understanding of the Anderson transition. However, the conductance of a disordered system is a fluctuating quantity which does not obey a one parameter scaling law. It is essential to investigate the scaling of the full conductance distribution to establish the scaling hypothesis. We present a clear cut numerical demonstration that the conductance distribution indeed obeys one parameter scaling near the Anderson transition

    Numerical verification of universality for the Anderson transition

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    We analyze the scaling behavior of the higher Lyapunov exponents at the Anderson transition. We estimate the critical exponent and verify its universality and that of the critical conductance distribution for box, Gaussian and Lorentzian distributions of the random potential
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