Pressure-driven dome-shaped superconductivity in topological insulator GeBi 2 Te 4 .

The discovery of new superconductors based on topological insulators always captures special attention due to their unique structural and electronic properties. High pressure is an effective way to regulate the lattice as well as electronic states in the topological insulators, thus altering their electronic properties. Herein, we report the structural and electrical transport properties of the topological insulator GeBi 2 Te 4 by using high-pressure techniques. The synchrotron x-ray diffraction revealed that GeBi 2 Te 4 underwent two structural phase transitions from R -3 m (phase I) to C 2/ m (phase II) and then into Im -3 m (phase III). Superconductivity was observed at 6.6 GPa to be associated with the first structural phase transition. The superconducting transition temperature T c reached a maximum value of 8.4 K, accompanied by the R H sign changing from negative to positive at 14.6 GPa, then gradually decreased with increasing pressure in phase III, showing a dome-shaped phase diagram. The present results provide a platform for understanding the interplay between the crystal structure and superconductivity by the regulation of pressure in the topological insulator materials.