Heat transport through plasmonic interactions in closely spaced metallic nanoparticle chains

We report a numerical investigation on the heat transfer through one-dimensional arrays of metallic nanoparticles closely spaced in a host material. Our simulations show that the multipolar interactions play a crucial role in the heat transport via collective plasmons. Calculations of the plasmonic thermal conductance and of the thermal conductivity in ballistic and diffusive regimes, respectively, have been carried out. (a) Using the Landauer-Buttiker formalism, we have found that, when the host material dielectric constant takes positive values, the multipolar interactions drastically enhance by several orders of magnitude the ballistic thermal conductance of collective plasmons compared with that of a classical dipolar chain. On the contrary, when the host material dielectric constant takes negative values, we have demonstrated the existence of nonballistic multipolar modes which annihilate the heat transfer through the chains. (b) Using the kinetic theory, we have also examined the thermal behavior of chains in the diffusion approximation. We have shown that the plasmonic thermal conductivity of metallic nanoparticle chains can reach 1% of the bulk metal thermal conductivity. This result could explain the anomalously high thermal conductivity observed in many colloidal suspensions, the so-called nanofluids.