Plasmonic thermal transport in graphene nanodisk waveguides

The thermal radiation properties of guided surface plasmons in one-dimensional co-planar graphene nanodisk arrays are predicted using a semi-analytical electrostatic model. The plasmonic band structure contains nonlocalized dispersion bands that are well-described by the electrostatic model for disk diameters smaller than 200 nm. A nondimensional model is proposed that enables systematic analysis of the waveguiding properties based on scaling laws. The thermal transport is dominated by the lowest-order radial modes and can be controlled by tuning the disk size, the substrate optical properties, and graphene's doping concentration and electron mobility. The maximum predicted thermal conductivity and thermal diffusivity are 4.$5{\mathrm{W}\phantom{\rule{0.16em}{0ex}}\mathrm{m}}^{\ensuremath{-}1}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ and $1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\phantom{\rule{4pt}{0ex}}{\mathrm{m}}²$/s, orders of magnitude larger than predictions of thermal transport by guided surface plasmon- or phonon-polaritons in other materials. The results suggest that graphene surface plasmons, which can be thermally-activated at room temperature, are a suitable platform for tunable and fast thermal transport, with potential application as photon-based thermotronic interconnects.