Pressure-induced enhancement of the superconducting transition temperature in La2O2Bi3AgS6

Abstract: Charge density wave (CDW) instability is often found in phase diagrams of superconductors such as cuprates and certain transition-metal dichalcogenides. This proximity to superconductivity triggers the question on whether CDW instability is responsible for the pairing of electrons in these superconductors. However, this issue remains unclear and new systems are desired to provide a better picture. Here, we report the temperature-pressure phase diagram of a recently discovered BiS$_2$ superconductor La$_2$O$_2$Bi$_3$AgS$_6$, which shows a possible CDW transition at $T^*\sim$155 K and a superconducting transition at $T_c\sim$1.0 K at ambient pressure, via electrical resistivity measurements. Upon applying pressure, $T^*$ decreases linearly and extrapolates to 0 K at 3.9 GPa. Meanwhile, $T_c$ is enhanced and reaches maximum value of 4.1 K at 3.1 GPa, forming a superconducting dome in the temperature-pressure phase diagram.