High-Pressure Synthesis of a Massive and Non-Symmorphic Dirac Semimetal Candidate MoP₄

Single crystal and polycrystalline samples of MoP$_4$ with a black-phosphorus-derived structure have been successfully synthesized by high-pressure technique. The show large positive magnetoresistance small negative Seebeck coefficient at low temperatures, reflecting semi-metallic nature high-mobility electrons. Consistent the transport properties, band calculation reveals state presence two types Dirac nodes slightly below Fermi level. node along $\Gamma$-X direction normal to phosphorus layers is gapped out in spin-orbit coupling (SOC), whereas crossing Z-point immune SOC because non-symmorphic symmetry. This work demonstrates great potential phosphorus-based layered Zintl compounds for topological semimetal candidates allowing chemical engineering.