Pressure induced insulator to metal transition in quantum spin liquid candidate NaYbS₂

Pressure induced insulator to metal transition followed by the appearance of superconductivity has been observed recently in inorganic quantum spin liquid candidate NaYbSe₂. In this paper, we study the properties of isostructural compound NaYbS₂ under pressure. It is found that the resistance of NaYbS₂ single crystal exhibits an insulating state below 82.9 GPa, but with a drop of more than six orders of magnitude at room temperature. Then a minimum of resistance is observed at about 100.1 GPa and it moves to lower temperature with further compression. Finally, a metallic state in the whole temperature range is observed at about 130.3 GPa accompanied by a non-Fermi liquid behavior below 100 K. The insulator to metal transition, non-monotonic resistance feature and non-Fermi liquid behavior of NaYbS₂ under pressure are similar to those of NaYbSe₂, suggesting that these phenomena might be the universal properties in NaLnCh₂ (Ln = rare earth, Ch = O, S, Se) system.