Superconductivity in Topological Semimetal θ-TaN at High Pressure*.

Recently, θ-TaN was proposed to be a topological semimetal with a new type of triply degenerate nodal points. Here, we report studies of pressure dependence of transport, Raman spectroscopy and synchrotron x-ray diffraction on θ-TaN up to 61 GPa. We find that θ-TaN becomes superconductive above 24.6 GPa with T_cat 3.1 K. The θ-TaN is of n-type carrier nature with carrier density about 1.1 × 10²⁰/cm³at 1.2 GPa and 20 K, while the carrier density increases with the pressure and saturates at about 40 GPa in the measured range. However, there is no crystal structure transition with pressure up to 39 GPa, suggesting the topological nature of the pressure induced superconductivity. [ABSTRACT FROM AUTHOR]