Electronic conduction of poly(dG)-poly(dC) DNA in SWNT/DNA/SWNT structure

  In this work, using a tight-binding Hamiltonian model, a generalized Greens function method and Löwdins partitioning techniques, some of the significant properties of the conductance of poly(dG)-poly(dC) DNA molecule in SWNT/DNA/SWNT structure are numerically investigated. In Fishbone model, we consider DNA as a planar molecule which contains M cells and 3 further sites (one base pair site and two backbone sites) in each cell sandwiched between two semi-infinite single-walled carbon nanotubes(SWNT) as the nano-electrodes. Relying on Landauer formalism as the basis for investigating the conductance properties of this system, we focus on the studying of the electron transmission and the current-voltage characteristics of DNA in the foregoing structure. In addition, in the presence of the electric potential between DNA molecule ends, our results suggest that the increasing of the value of applied bias give rise to the large enhancement in the conductance of the system. We also find that, as the tube radius increases, the conductance of the system considerably increases

Effects of dephasing on the spin-dependent currents and noise power in a molecular junction

The role of dephasing reservoirs on the spin-dependent transport through a polythiophene (PT) molecule sandwiched between ferromagnetic 3-dimensional electrodes as a FM/PT/FM junction is numerically investigated. Our calculations are performed based on a tight-binding model and a generalized Green’s function method in the well-known Landauer-Büttiker formalism. We investigate the influence of dephasing reservoirs on the spin dependent currents, noise power, Fano factor and tunnel magnetoresistance (TMR) of the junction. Our results illustrate that the presence of dephasing reservoirs give rise to increase the currents and noise power due to reduced destructive interference resulting from the Büttiker probes. We found the significant change in the Fano factor and TMR of the FM/PT/FM junction in the presence of dephasing reservoirs. Furthermore, we explore the influence of the electrode/molecule coupling strength on the transport properties of the FM/PT/FM junction. It is shown that the electrode/molecule coupling strength may control the spin-dependent transport properties and so it is a significant parameter for designing of the efficient molecular spintronic devices