For further research, we use superc

For further research, we use superconducting magnet to identify the 2D superconductivity of these grown ultrathin Mo2C films. Fig. 3a shows the temperature dependence of resistivity of these grown Mo2C films with several thickness. As a superconducting material, the 2D Mo2C films usually show the onset temperature (Tonset) of superconductivity at 2-6 K.11,15,16 We perform variable temperature electrical measurements to test the conductivity of the grown Mo2C films. This 2.3 nm film shows the onset temperature of conductivity at 5.36 K, shown in the inset in Fig. 3a, and the temperature of zero resistance is about 5 K, which is much thinner than those Mo2C crystals fabricated by one-step CVD method. The critical transition temperature (Tc) of this film is 5.2 K, defined as the temperature where the resistance of the film drops to 10% of its resistance at normal state.