  We investigate the near-field heat transfer between a semi-infinite medium
and a nanoparticle made of composite materials. We show that, in the effective
medium approximation, the heat transfer can be greatly enhanced by considering
composite media, being maximal at the percolation transition. Specifically, for
titanium inclusions embedded in a polystyrene sphere, this enhancement can be
up to thirty times larger than in the case of the corresponding homogeneous
titanium sphere. We demonstrate that our findings are robust against material
losses, to changes in the shape of inclusions and materials, and apply for
different effective medium theories. These results suggest the use of composite
media as a new, versatile material platform to enhance, optimize, and tailor
near-field heat transfer in nanostructures.
