1Institute of Physics, Chinese Academy of Sciences, Beijing 100190 2School of Physics, University of Chinese Academy of Sciences, Beijing 100190 3Songshan Lake Materials Laboratory, Guangdong 523808 4School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 5Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049
Abstract：Recently, $\theta$-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 $\theta$-TaN up to 61 GPa. We find that $\theta$-TaN becomes superconductive above 24.6 GPa with $T_{\rm c}$ at 3.1 K. The $\theta$-TaN is of n-type carrier nature with carrier density about $1.1\times 10^{20}$/cm$^{3}$ 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.
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2019, Vol. 36 
