Superconductivity in Topological Semimetal θ-TaN at High Pressure**Supported by the National Key Research and Development Program of China under Grant No 2018YFA0305701.

Abstract

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 Tc at 3.1 K. The θ-TaN is of n-type carrier nature with carrier density about 1.1 × 1020/cm3 at 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.