Colossal conductivity anisotropy in 3D metallic carbon films

Harnessing the phenomena of quantum coherence and destructive interference, we have successfully engineered and synthesized a three-dimensional (3D) graphene-based film exhibiting remarkable properties, including metallic thermal conductivity (κ ≈ 150 Wm⁻1K⁻1) and electrical conductivity (σ ≈ 320 kSm⁻1) at room temperature. Notably, these films demonstrate colossal transport anisotropies, reaching approximately 103 for thermal and 105 for electrical conductivity. This places them among the conducting materials with the highest anisotropies known to date, surpassing even the performance of one-dimensional (1D) carbon nanotubes and two-dimensional (2D) materials like h-BN and MoS₂. These films are synthesized by self-assembly and cross-linking of edge-hydrolyzed graphene flakes. The electron transport between flakes is phonon mediated and at low temperatures the films present quantum critical behavior of a metal to Anderson insulator transition. We measure the electron transport properties in a Hall bar geometry and extract the critical exponents as a function of the sample mobility. [Display omitted] •Edge hydrolyzed graphene self-assembles into highly ordered metallic films.•Films with in-plane quantum coherence and through-plane destructive interference.•Extreme thermal (ρk∼103) and electrical (ρσ∼105) conductivity anisotropies.•The electron transport between flakes is phonon mediated.•Reversible metal to Anderson insulator transition at low temperatures.