112 research outputs found
Probability distribution of the conductance at the mobility edge
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 and are
discussed in detail and relation in the limit 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
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
Electron transport in strongly disordered structures
Using the transfer matrix technique, we investigate the propagation of
electron through a two dimensional disordered sample. We find that the spatial
distribution of electrons is homogeneous only in the limit of weak disorder
(diffusive transport regime). In the limit of very strong disorder, we identify
a narrow channel through which the electron propagates from one side of the
sample to the opposite side. Even in this limit, we prove the wave character of
the electron propagation.Comment: Presented at ETOPIM
Symmetry, dimension and the distribution of the conductance at the mobility edge
The probability distribution of the conductance at the mobility edge,
, in different universality classes and dimensions is investigated
numerically for a variety of random systems. It is shown that is
universal for systems of given symmetry, dimensionality, and boundary
conditions. An analytical form of for small values of is discussed
and agreement with numerical data is observed. For , is
proportional to rather than .Comment: 4 pages REVTeX, 5 figures and 2 tables include
Absorption losses in periodic arrays of thin metallic wires
We analyze the transmission and reflection of the electromagnetic wave
calculated from transfer matrix simulations of periodic arrangements of thin
metallic wires. The effective permittivity and the absorption is determined.
Their dependence on the wire thickness and the conductance of the metallic
wires is studied. The cutoff frequency or effective plasma frequency is
obtained and is compared with analytical predictions. It is shown that the
periodic arrangement of wires exhibits a frequency region in which the real
part of the permittivity is negative while its imaginary part is very small.
This behavior is seen for wires with thickness as small as 17 m with a
lattice constant of 3.33 mm
Resonant and anti-resonant frequency dependence of the effective parameters of metamaterials
We present a numerical study of the electromagnetic response of the
metamaterial elements that are usedto construct materials with negative
refractive index. For an array of split ring resonators (SRR) we find that the
resonant behavior of the effective magnetic permeability is accompanied by an
anti-resonant behavior of the effective permittivity. In addition, the
imaginary parts of the effective permittivity and permeability are opposite in
sign. We also observe an identical resonant versus anti-resonant frequency
dependence of the effective materials parameters for a periodic array of thin
metallic wires with cuts placed periodically along the length of the wire, with
roles of the permittivity and permeability reversed from the SRR case. We show
in a simple manner that the finite unit cell size is responsible for the
anti-resonant behavior
Electronic transport in strongly anisotropic disordered systems: model for the random matrix theory with non-integer beta
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
Impact of the inherent periodic structure on the effective medium description of left-handed and related meta-materials
We study the frequency dependence of the effective electromagnetic parameters
of left-handed and related meta-materials of the split ring resonator and wire
type. We show that the reduced translational symmetry (periodic structure)
inherent to these meta-materials influences their effective electromagnetic
response. To anticipate this periodicity, we formulate a periodic effective
medium model which enables us to distinguish the resonant behavior of
electromagnetic parameters from effects of the periodicity of the structure. We
use this model for the analysis of numerical data for the transmission and
reflection of periodic arrays of split ring resonators, thin metallic wires,
cut wires as well as the left-handed structures. The present method enables us
to identify the origin of the previously observed resonance/anti-resonance
coupling as well as the occurrence of negative imaginary parts in the effective
permittivities and permeabilities of those materials. Our analysis shows that
the periodicity of the structure can be neglected only for the wavelength of
the electromagnetic wave larger than 30 space periods of the investigated
structure.Comment: 23 pages, 14 figure
Disordered two-dimensional electron systems with chiral symmetry
We review the results of our recent numerical investigations on the
electronic properties of disordered two dimensional systems with chiral
unitary, chiral orthogonal, and chiral symplectic symmetry. Of particular
interest is the behavior of the density of states and the logarithmic scaling
of the smallest Lyapunov exponents in the vicinity of the chiral quantum
critical point in the band center at E=0. The observed peaks or depressions in
the density of states, the distribution of the critical conductances, and the
possible non-universality of the critical exponents for certain chiral unitary
models are discussed
Character of eigenstates of the 3D disordered Anderson Hamiltonian
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
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