  The recently discovered Dirac and Weyl semimetals are new members of
topological materials. Starting from them, topological superconductivity may be
achieved, e.g. by carrier doping or applying pressure. Here we report
high-pressure resistance and X-ray diffraction study of the three-dimensional
topological Dirac semimetal Cd3As2. Superconductivity with Tc ~ 2.0 K is
observed at 8.5 GPa. The Tc keeps increasing to about 4.0 K at 21.3 GPa, then
shows a nearly constant pressure dependence up to the highest pressure 50.9
GPa. The X-ray diffraction measurements reveal a structure phase transition
around 3.5 GPa. Our observation of superconductivity in pressurized topological
Dirac semimetal Cd3As2 provides a new candidate for topological superconductor,
as argued in a recent point contact study and a theoretical work.
