Prof Arzhang Ardavan

Abstract:

An experimental implementation of an oscillating, superluminal polarization current distribution that undergoes centripetal acceleration was constructed and tested. The emission from the experimental machine was found to be tightly beamed in both the azimuthal and polar directions. It was found that the beaming is frequency independent and has a sharply defined and unchanging geometry determined only by the speed and path of the moving distribution pattern. The intensity of the radiation at these angles was observed to decline more slowly with increasing distance from the source than would the emission from a conventional antenna.

Abstract:

A clear understanding of the interactions between the building blocks of self-assembled molecular materials is essential for rational design of functional nanostructures. Intermolecular interactions have been investigated for three different classes of fullerenes in single-walled carbon nanotubes (SWNTs); van der Waals molecule -molecule and molecule-SWNT interactions control the geometry of the molecular arrays inside nanotubes; electrostatic intermolecular forces influence the alignment of polar endohedral fullerenes M@C-82; and hydrogen bonding between functionalised fullerenes has a significant effect on the selectivity of insertion of functionalised fullerenes into SWNTs.

Abstract:

The angle dependences of the magnetoresistance of two different isotopic substitutions (deuterated and undeuterated) of the layered organic superconductor κ-(ET)2Cu(NCS)2 are presented (where ET is the organic molecule bis(ethylenedithio)-tetrathiafulvalene). The angle-dependent magnetoresistance oscillations (AMRO) arising from the quasi-one-dimensional and quasi-two-dimensional Fermi surfaces in this material are easily confused. By using the Boltzmann transport equation extensive simulations of the AMRO are made that reveal the subtle differences between the different species of oscillation. No significant differences are observed in the electronic parameters derived from quantum oscillations and AMRO for the two isotopic substitutions. The interlayer transfer integrals are determined for both isotopic substitutions and a slight difference is observed which may account for the negative isotope effect previously reported. The success of the semiclassical simulations suggests that non-Fermi liquid effects are not required to explain the interlayer transport in this system.