Electrostatic electron-doping yields superconductivity in LaOBiS₂

Electrostatic carrier-doping is attracting serious attention as a meaningful technique for producing interesting electronic states in two-dimensional (2D) layered materials. Ionic-liquid gating can provide the critical carrier density required to induce the metal-insulator transition and superconductivity. However, the physical properties of only a few materials have been controlled by the electrostatic carrier-doping during the past decade. Here, we report an observation of superconductivity in a 2D layered material, LaOBiS₂, achieved by the electrostatic electron-doping. The electron doping of LaOBiS₂ induced metallic conductivity in the normally insulating LaOBiS₂, ultimately led to superconductivity. The superconducting transition temperature, T_c, was 3.6 K, higher than the 2.7 K seen in LaO_1-xF_xBiS₂ with an electron-doped BiS₂ layer. A rapid drop in resistance (R) was observed at low temperature, which disappeared with the application of high magnetic fields, implying a superconducting state. This study reveals that electron-doping is an important technique for inducing superconductivity in 2D layered BiS₂ materials.