Plasmon Thermal Conductance and Thermal Conductivity of Metallic Nanofilms

Abstract

The thermal conductance and thermal conductivity of surface plasmon polaritons propagating along a metallic nanofilm deposited on a substrate are quantified and analyzed, as functions of the film thickness, length, and temperature. This is done by analytically solving the dispersion relation of plasmons for their wave vectors and propagation length. It is shown that the plasmon energy transport along the film interfaces is driven by two modes characterized by symmetric and antisymmetric spatial distributions of the magnetic field. For a gold nanofilm deposited on a silicon substrate, both modes have comparable contributions of the plasmon thermal conductance, which takes higher values for hotter and/or longer nanofilms and saturates for films thicker than 50 nm. This saturation arises from the decoupling of the plasmon modes, the transition of which to a coupled state for thinner films maximizes the plasmon thermal conductivity. For a 1-cm-long gold nanofilm at 300 K, the maximum thermal conductivity appears for a thickness of 10 nm and takes the value of 15 W m −1 K −1 , which is about 25% of its electron counterpart. As a result of the huge propagation distance (> 1 cm) of plasmons, this plasmon thermal conductivity increases significantly with the film length and temperature and it could therefore be useful to improve the heat dissipation along metallic nanofilms.

Long-range, short-wavelength, and ultrafast heat conduction driven by three plasmon modes supported by graphene

“…This is also the case of surface plasmon polaritons (SPPs) generated by the hybridization of * jose.ordonez@cnrs.fr photons and free electrons in metallic nanofilms. The plasmonic heat conduction along these nanofilms is driven by two fundamental plasmon modes [16,17], whose contribution to significantly boost the in-plane thermal conductivity of a Ti nanofilm was recently observed experimentally [18]. These works [15,16,18] suggest that the plasmonic heat conduction could naturally be enhanced via highly conductive two-dimensional (2D) materials.…”

“…The plasmonic heat conduction along these nanofilms is driven by two fundamental plasmon modes [16,17], whose contribution to significantly boost the in-plane thermal conductivity of a Ti nanofilm was recently observed experimentally [18]. These works [15,16,18] suggest that the plasmonic heat conduction could naturally be enhanced via highly conductive two-dimensional (2D) materials. Even though the electron thermal conductivity of graphene has been widely studied [19][20][21][22][23] along with its ability to support plasmon modes [24][25][26], their contribution to the heat conduction is not known yet.…”