Pressure-induced superconductivity in AgxBi2-xSe3

We investigated the pressure dependence of electric transport and crystal structure of Ag-doped Bi2Se3. In the sample prepared by Ag doping of Bi2Se3, the Bi atom was partially replaced by Ag, i.e., Ag0.05Bi1.95Se3. X-ray diffraction patterns of Ag0.05Bi1.95Se3 measured at 0-30 GPa showed three different structural phases, with rhombohedral, monoclinic, and tetragonal structures forming in turn as pressure increased, and structural phase transitions at 8.8 and 24 GPa. Ag0.05Bi1.95Se3 showed no superconductivity down to 2.0 K at 0 GPa, but under pressure, superconductivity suddenly appeared at 11 GPa. The magnetic field (H) dependence of the superconducting transition temperature T-c was measured at 11 and 20.5 GPa, in order to investigate whether the pressure- induced superconducting phase is explained by either p-wave polar model or s-wave model.