Pressure effects on superconductivity of Fe1+yTe1−xSx single crystals

We have investigated the pressure effect on superconductivity of Fe1+yTe1−xSx single crystals. We show that the applied pressure leads to opposite variation in the superconductivity between homogeneous and inhomogeneous samples. With increasing pressure to 10 kbar, the superconductivity of homogenous sample S1 is suppressed gradually, however Tcmag of inhomogeneous S4 can be raised up to 21 K. The increase in Tcmag in S4 is believed as stabilizing the structure by strain effect in inhomogeneous sample, thereby avoiding structural transition under pressure. Our results imply that higher Tc could be expected in iron chalcogenides if this structural instability could be suppressed.