Figure 2. Experimental evidence of pressure-induced superconductivity.

(a) The temperature-dependent resistance under different pressures up to 16.1 GPa in run no. 1. The inset shows the temperature-dependent resistance from 1.8 to 300 K at 2.5 GPa. The onset of superconductivity can be seen from the drop in resistance. (b) Temperature dependence of resistance under various pressures from 9.3 to 68.5 GPa in run no. 2. (c) Magnetoresistance comparison at 10 K between ambient pressure and 2.5 GPa. Magnetoresistance is strongly suppressed with increasing pressure when superconductivity becomes predominant. (d) The real part of the a.c. susceptibility versus temperature at different pressures.