We also study the superconductivity

We also study the superconductivity dependence on the strength and direction of the magnetic field. Fig. 3b shows the superconducting resistive transition of a 2.3-nm-thick Mo2C film for different out-of-plane magnetic field strengths. The inset in Fig. 3b shows the influences of external out-of-plane and in-plane magnetic fields on the superconducting characteristics for 2.3 nm Mo2C films. As for the out-of-plane case, Hc2⊥ shows a linear behavior close to Tc, which is accorded with the standard linearized Ginzburg–Landau (GL) theory for superconductors. The voltage-current (V -I ) characteristics of this system shown in Fig. 3c are also measured at selected temperatures ranging from 4.3K to 5.2K without the presence of an external magnetic field. The measurements show the power-law dependence, V∝Iα, in line with expectations of 2D superconducting theory model on the basis of Berezinskii–Kosterlitz–Thouless (BKT) transition.20,21 We take the logarithm and the results are shown in Fig. 3d. The analysis on the V-I characteristics reveals the signature of BKT transition, which is another evidence for its 2D superconductivity. When exponent α reaches to a value of 3, we determined the temperature as the BKT transition temperature TBKT=4.97K.