Liquid-gated superconductor-insulator transition in an electron-doped cuprate

Doping charge carriers will causes the change of cuprates from antiferromagnetic Mott insulators to high-$T_{c}$ superconductors. Continuous changing of carrier density is necessary to understand the nature of such phase transition, and thus, further our understanding of cuprate superconductors. Electric field-effect doping, especially with electronic double layer transistors (EDLT) configuration which use ionic liquids (ILs) and polymer electrolyte as the gate dielectrics, is a potential avenue for this investigation and it has been shown its effectiveness in inducing phase transition in strongly correlated electron system. Owing to EDLT, superconductor-to-insulator transition (SIT) has been observed in hole-doped cuprates La$_{2-x}$Sr$_{x}$CuO$_{4}$ and YBa$_{2}$Cu$_{3}$O$_{y}$. Here we use EDLT to tune the carrier density in electron-doped cuprates Pr$_{2-x}$Ce$_{x}$CuO$_{4}$ ultrathin films and cause the sample evolves from a superconducting state to an insulating state. This present results could be helpful to study SIT between electron- and hole-doped cuprates.