Recent spatially resolved measurements of the electrostatic-potential variation across a Hall bar in strong magnetic fields, which revealed a clear correlation between current-carrying strips and incompressible strips expected near the edges of the Hall bar, cannot be understood on the basis of existing equilibrium theories. To explain these experiments, we generalize the Thomas-FermiPoisson approach for the self-consistent calculation of electrostatic potential and electron density in total thermal equilibrium to a local equilibrium theory that allows to treat finite gradients of the electrochemical potential as driving forces of currents in the presence of dissipation. A conventional conductivity model with small values of the longitudinal conductivity for integer values of the (local) Landau-level filling factor shows that, in apparent agreement with experiment, the current density is localized near incompressible strips, whose location and width in turn depend on the applied current.

We report true left-handed (LH) behavior in a composite metamaterial consisting of a periodically arranged split ring resonator (SRR) and wire structures. We demonstrate the magnetic resonance of the SRR structure by comparing the transmission spectra of SRRs with those of closed SRRs. We have confirmed experimentally that the effective plasma frequency of the LH material composed of SRRs and wires is lower than the plasma frequency of the wires. A well-defined LH transmission band with a peak value of -1.2 dB (-0.3 dB/cm) was obtained. The experimental results agree extremely well with the theoretical calculations.

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Cataloged from PDF version of article.We report the transmission characteristics of a two-dimensional (2D) composite metamaterial (CMM) structure in free space. At the frequencies where left-handed transmission takes place, we experimentally confirmed that the CMM structure has effective negative refractive index. Phase shift between consecutive numbers of layers of CMM is measured and phase velocity is shown to be negative at the relevant frequency range. Refractive index values obtained from the refraction experiments and the phase measurements are in good agreement. (C) 2005 American Institute of Physics

We experimentally and theoretically studied a left-handed structure based on a photonic crystal ͑PC͒ with a negative refractive index. The structure consists of triangular array of rectangular dielectric bars with dielectric constant 9.61. Experimental and theoretical results demonstrate the negative refraction and the superlensing phenomena in the microwave regime. The results show high transmission for our structure for a wide range of incident angles. Furthermore, surface termination within a specific cut of the structure excite surface waves at the interface between air and PC and allow the reconstruction of evanescent waves for a better focus and better transmission. The normalized average field intensity calculated in both the source and image planes shows almost the same full width at half maximum for the source and the focused beam. DOI: 10.1103/PhysRevB.71.085106 PACS number͑s͒: 42.25.Ϫp, 78.20.Ci, 41.20.Jb Left-handed-materials ͑LHM͒ are materials with simultaneously negative dielectric permittivity ͑r͒ and negative magnetic permeability ͑r͒. The phase velocity of the light wave propagating inside this medium is pointed in the opposite direction of the energy flow. Thus, the Poynting vector and wave vector are antiparallel, consequently, the light is refracted negatively. The existence and impact of such materials was pointed out by Veselago.1 Years later, several theoretical and experimental groups investigated the LHM.2-5 For LHM based on photonic crystals ͑PCs͒, Notomi studied light propagation in a strongly modulated two-dimensional ͑2D͒ PC. 6 Luo et al. have studied subwavelength imagining in PCs.7 Cubukcu et al. demonstrated experimentally singlebeam negative refraction and superlensing in the valence band of 2D PCs operating in the microwave regime. 8 Foteinopoulou et al. emphasized the time evolution of an EM wave as it hits the interface between a right-handed ͑RH͒ and a LH material interface.9 Pendry suggested that a slab of lossless LHM with both ͑r͒ and ͑r͒ equal to Ϫ1 should behave as a perfect lens, 10 i.e, the small details as well as the larger ones could be reproduced by such a lens. The reconstruction of the evanescent wave components is the key to such perfect focusing. It is shown in another study 11 how the evanescent waves get amplified upon reaching the interface between a RH and LH medium and consequently how they participate in improving the quality of the image. Homogeneous metamaterials and PCs were used to demonstrate the effect. The main challenge is to find a structure with n =−1 for which the matching condition are verified with no reflections. The candidate structure should have three characteristics. First, it should exhibit almost isotropic equal frequency surfaces ͑EFS͒ in a band region with v g · k Ͻ 0, with k being the wave vector in the first Brillouin zone ͑BZ͒ and v g is the group velocity. The latter implies S · k Ͻ 0, 12 and thus LH behavior. 5 Second, it should guarantee the absence of any higher order Bragg reflections for any angle of incidence. Finally ...

The existence of a left-handed ͑LH͒ transmission band in a bulk composite metamaterial ͑CMM͒ around 100 GHz is demonstrated experimentally. The CMM consists of stacked planar glass layers on which periodic patterns of micron-scale metallic wires and split-ring resonators are fabricated. The LH nature of the CMM band is proved by comparing the transmission spectra of individual CMM components. Theoretical investigation of the CMM by transmission simulations and an inversion scheme for the retrieval of the effective permeability and permittivity functions supports the existence of LH behavior.

We report the spectral refraction analysis and focusing properties of a two-dimensional, dielectric photonic crystal (PC) slab in freespace. A transverse electric polarized upper band of the crystal is used. The measured refraction spectra indicates that a highly isotropic negative index of refraction is present in the measured frequency range of the band. We demonstrate experimentally and numerically the focusing of the field emitted from an omnidirectional source placed in front of the crystal. Both the source and the focus pattern are away from the PC interfaces of the order of several wavelengths. The focus pattern mimics the arbitrary lateral and longitudinal shifts of the source, which is a manifestation of true flat lens behavior

We investigated the influence of periodicity, misalignment, and disorder on the magnetic resonance gap of split-ring resonators (SRRs) which are essential components of left handed-metamaterials (LHMs). The resonance of a single SRR which is induced by the split is experimentally demonstrated by comparing transmission spectra of SRR and closed ring resonator. Misaligning the SRR boards do not affect the magnetic resonance gap, while destroying the periodicity results in a narrower band gap. The disorder in SRR layers cause narrower left-handed pass band and decrease the transmission level of composite metamaterials (CMMs), which may significantly affect the performance of these LHMs.