Pressure-induced Superconductivity in BiS2-based Superconductors Eu2SrBi2S2.5Se1.5F4

BiS2-based superconductor Eu2SrBi2S2.5Se1.5F4 has been investigated to clarify between Tc and crystal structure under high-pressure. The electrical resistivity by Cubic anvil cell and XRD by Diamond anvil cell were measured by generating hydrostatic pressure. In electrical resistivity measurements, Tc increased from 2.05 to 3.22 K at 1.5 GPa and decreased below 2.62 K at 3 GPa. However, under higher-pressure, Tc exhibited a peak again at 4 GPa. These experimental results suggest the existence of pressure-induced multiple superconducting phases in Eu2SrBi2S2.5Se1.5F4. By XRD measurements, we can find that pressure-induced structural phase transitions occur near the pressure in the observation of Tc discontinuities. These results indicate the emergence of new superconducting phases through structural phase transitions. Eu2SrBi2S2.5Se1.5F4 was found to have three superconducting phases up to 12 GPa.