van der Waals (vdW) layered compounds provided a fruitful research platform for the realization of superconductivity. However, a vdW layered superconductor with a high transition temperature ($T_c$) at ambient conditions is still rare. Here, using variable-composition evolutionary structure predictions, we systematically explored the stable compounds in the P-S system up to 20 GPa. Opposed to the complex stoichiometries at ambient conditions, only one compound, ${\mathrm{PS}}_2$, is predicted to be thermodynamically stable above 8 GPa. Strikingly, ${\mathrm{PS}}_2$ is a vdW layered material isostructural to $3R-{\mathrm{MoS}}_2$ exhibiting a predicted $T_c$ of around 11 K at ambient pressure, both in the bulk and the monolayer form. ${\mathrm{PS}}_2$ has been successfully synthesized via high-pressure experiments following the theoretical predictions. This enables replacing transition metals with group V elements in transition-metal dichalcogenides and paves the way in the search for vdW layered materials with superior properties.

• Received 21 February 2019
• Revised 7 May 2019

DOI:https://doi.org/10.1103/PhysRevB.99.220503