Carbon nanorings for spintronics applications

M. Encinosa, M. Jack
Florida A&M University, US

Keywords: toroidal carbon nanotube, electron transport, magnetic flux, gate voltage, Fermi level, Green’s function, tight-binding, Aharonov-Bohm oscillation, universal conductance fluctuation, magnetic moment

Abstract:

Novel electronic transport and spin control characteristics of carbon nanostructures under optical excitation make them promising candidates for spintronics device applications with added biosensory capabilities. For a toroidal carbon nanotube, small bias transport under microwave illumination is calculated in a tight-binding approximation using a non-equilibrium Green’s function methods. Metallic leads are attached below the torus geometry to simulate realistic device architectures for different electronic device-to-lead couplings. Density-of-states D(E), transmission function T(E) and source-drain current ISD are compared e.g. for a (3,3) armchair and a (6,0) zigzag carbon nanotorus. Polarized coherent microwave radiation with added constant magnetic field oriented along the central toroidal axis are expected to generate coherent transport features. Further, off-axis magnetic moments arising from currents circulating around the toroidal minor radius exist, which are of potential interest for spintronics applications. Significant computational speed-up is expected for a parallelized algorithm on a multi-core computer cluster applying fast SCALAPACK routines for band matrices. The dependence of transport parameters on torus size and curvature will be studied for different realistic nanodevice sizes of a few thousand or more atoms.