Theory of Optical Transmission through Elliptical Nanohole Arrays

We present a theory which explains (in the quasistatic limit) the experimentally observed [R. Gordon, {\it et al}, Phys. Rev. Lett. {\bf 92}, 037401 (2004)] squared dependence of the depolarization ratio on the aspect ratio of the holes, as well as other features of extraordinary light transition. We calculated the effective dielectric tensor of a metal film penetrated by elliptical cylindrical holes and found the extraordinarily light transmission at special frequencies related to the surface plasmon resonances of the composite film. We also propose to use the magnetic field for getting a strong polarization effect, which depends on the ratio of the cyclotron to plasmon frequencies.Comment: 4 pages, 4 figure

Percolation model for the superconductor-insulator transition in granular films

We study the temperature dependence of the superconductor-insulator transition in granular superconductors. Empirically, these systems are characterized by very broad resistance tails, which depend exponentially on the temperature, and the normal state resistance. We model these systems by a two-dimensional random resistor percolation networks in which the resistance between two grains is governed either by Josephson junction coupling or by quasi particle tunneling. Our numerical simulations as well as an effective medium evaluation explain the experimental results over a wide range of temperatures and resistances. Using effective medium approximation we find an analytical expression for the effective resistance of the system and the value of the critical resistance separating conducting from insulating branches.Comment: 4 pages, 2 figure

Magnetotransport in a periodic composite medium: New phenomena in a classical physics context

The magnetotransport properties of a composite conductor with a periodic microstructure have recently been studied both theoretically and numerically using a local classical continuum physics description of the transport at the microscale. Surprising new phenomena were discovered, including an induced magnetoresistance which oscillates strongly when the magnetic field is sufficiently strong and is rotated with respect to the microstructure. A surprising aspect of this phenomenon is that the effect is much stronger when the microstructure is two dimensional than when it is three dimensional. The physical reasons for this are discussed. Briefly, this is concerned with the question of whether the current distribution saturates with increasing strength of the magnetic field. In two-dimensional metal-insulator microstructures, the magnetoresistance usually does not saturate. But when it does, some components of the local current distribution must exhibit a surprising degree of uniformity over the conducting constituent