The 45K Onset Superconductivity and the Suppression of the Nematic Order in FeSe by Electrolyte Gating

The electronic doping effect on both the superconductivity and the nematic order in the FeSe nanoflake are investigated by using the electric-double-layer transistor configuration. The superconductivity can be effectively controlled by electronic doping, and the onset superconducting transition temperature T_\rm c reaches as high as 45 K at a gate voltage of V_\rm g=4 V. Meanwhile, the nematic phase is gradually suppressed with the increase of electronic doping (or V_\rm g). The results provide an effective method with variable charge doping for investigation of the rich physics in the FeSe superconductor.