Pressure-induced superconductivity up to 13.1 K in the pyrite phase of palladium diselenide PdSe2

The family of transition-metal dichalcogenides provides a rich platform for studying the interplay between the crystal structure and electronic properties in strongly correlated electron systems. Applying external pressure as a tuning parameter, the authors observed a striking correlation between the critical temperature ${T}_{c}$ for superconductivity and the strength of the Se-Se bonds in the high-pressure pyrite phase of PdSe${}_{2}$. The bond length of the Se${}_{2}$ dimer was identified as the main parameter for controlling the superconductivity in the pyrite structure. Strong pressure-induced enhancement of ${T}_{c}$ up to its maximum value of 13.1 K cannot, however, be explained solely by phonon softening, and this implies the relevance of additional factors influencing ${T}_{c}$. Indeed, electronic band calculations reveal the presence of topologically nontrivial states in the pyrite structure.