Universal quantum phase transition from superconducting to insulating-like states in pressurized Bi2Sr2CaCu2O8+δ superconductors

Copper oxide superconductors have been continually fascinating the communities of condensed matter physics and material sciences because they host the highest ambient-pressure superconducting transition temperature ( T c ) and mysterious physics 1–3. Searching for the universal correlation between the superconducting state and its normal state or neighboring ground state is believed to be an effective way for finding clues to elucidate the underlying mechanism of the superconductivity. One of the common pictures for the copper oxide superconductors is that a well-behaved metallic phase will present after the superconductivity is entirely suppressed by chemical doping 4–8 or application of the magnetic field 9. Here, we report the first observation of universal quantum phase transition from superconducting state to insulating-like state under pressure in the under-, optimally- and over-doped Bi2Sr2CaCu2O8+δ (Bi2212) superconductors with two CuO2 planes in a unit cell. The same phenomenon has also been found in the Bi2Sr1.63La0.37CuO6+δ (Bi2201) superconductor with one CuO2 plane and the Bi2.1Sr1.9Ca2Cu3O10+δ (Bi2223) superconductor with three CuO2 planes in a unit cell. These results not only provide fresh information on the cuprate superconductors but also pose a new challenge for achieving unified understandings on the mechanism of the high-Tc superconductivity.