Pressure-induced superconductivity in topological heterostructure (PbSe) 5 (Bi 2 Se 3 ) 6

Recently, the natural heterostructure of (PbSe) 5 -(Bi 2 Se 3 ) 6 has been theoretically predicted and experimentally confirmed as a topological insulator. In this work, we induce superconductivity in (PbSe) 5 (Bi 2 Se 3 ) 6 by implementing high pressures. As the pressure increases up to 10 GPa, superconductivity with a critical temperature ( T c ) ~ 4.6 K suddenly appears, which is followed by an abrupt decrease. Remarkably, upon further compression above 30 GPa, a new superconducting state arises, where pressure raises the T c to an unsaturated 6.0 K within the limit of our research. Combining X-ray diffraction and Raman spectroscopy, we suggest that the emergence of the two distinct superconducting states occurs concurrently with the pressure-induced structural transition in this topological heterostructure (PbSe) 5 (Bi 2 Se 3 ) 6 .