Thermal transport in superconducting niobium nitride: A first-principles study

Superconducting metallic transition-metal nitrides, especially from the family of NbNx, are promising in various applications. Due to the fact that the lattice constants and the crystal structures are similar to those of GaN, GaN/NbN heterostructures have been grown to combine the benefits of superconductors and semiconductors, where the thermal transport property is of great significance. In this Letter, the thermal transport property of metallic hexagonal NbN is studied using a first-principles approach with the consideration of both electron and phonon scatterings. It is interesting to find that unlike most metals, phonons play a bigger role in hexagonal NbN compared to electrons, due to a relatively small electron density of states near the Fermi level. At room temperature, our calculated thermal conductivity is close to the experimental data. Our findings can provide a deeper understanding of how heat is transported in metallic transition-metal nitrides and may help design semiconductor/superconductor heterostructures.