Pressure-driven superconducting dome in the vicinity of CDW in the pyrite-type superconductor CuS2

Abstract

Prior to the superconducting transition at ${T}_{\mathrm{c}}\ensuremath{\approx}1.5\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, the pyrite-type ${\mathrm{CuS}}_{2}$ undergoes a charge-density-wave (CDW) transition at ${T}_{\mathrm{s}}\ensuremath{\approx}150\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ at ambient pressure. Here we studied the interplay between CDW and superconductivity (SC) in ${\mathrm{CuS}}_{2}$ by tracking their evolutions with pressure via detailed measurements of resistivity and magnetic susceptibility under hydrostatic pressures up to 6.6 GPa. The high-quality ${\mathrm{CuS}}_{2}$ samples used in the present study were synthesized under high-pressure and high-temperature conditions, and the formation of the $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2$ supercell associated with the commensurate CDW order below ${T}_{\mathrm{s}}$ was confirmed by low-temperature transmission electron microscope. Our high-pressure results uncover a pressure-driven superconducting dome with an enhanced ${{T}_{\mathrm{c}}}^{max}\ensuremath{\sim}2.3\phantom{\rule{0.28em}{0ex}}\mathrm{K}$ at $\ensuremath{\sim}1.8\phantom{\rule{0.28em}{0ex}}\mathrm{GPa}$ accompanying the gradual suppression of the CDW order. This work thus demonstrates the competing nature between CDW and SC in the pyrite-type superconductor ${\mathrm{CuS}}_{2}$.