Pressure‐Enhanced Superconductivity in EuSr2Bi2S4−xSexF4 and Eu2SrBi2S4−x SexF4 (x = 1.5, 2)

The dc magnetization of Se‐doped Eu2SrBi2S4−xSexF4 and EuSr2Bi2S4−xSexF4 (x = 1.5 and 2) superconductors is measured under external hydrostatic pressure. All the samples exhibit an enhanced superconducting transition temperature (Tc) upto ≈1 GPa. There is a possible crystallographic transformation by the application of pressure from a structure of low Tc to a structure corresponding to high Tc. The maximum Tc of ≈3.4 K is observed in EuSr2Bi2S2Se2F4 (positive pressure coefficient 1.08 K GPa−1). Critical current density Jc = 0.38 × 104 A cm−2 at 2 K (1 GPa) upto 0.05 T is estimated using Bean's model. EuSr2Bi2S2Se2F4 has lower critical field (Hc1) ≈100 Oe. To our knowledge, this is the first report of pressure‐dependent critical current density with application of magnetization studies in Eu‐3244‐based superconducting materials. This work devotes the effort to establish the commonality of pressure effect on the BiS2‐based superconductors, and also uncovers the importance of electron carrier density in the high‐Tc phase. The external pressure on Eu‐3244 superconductors potentially strengthens the hybridization between Eu‐4f and Bi‐6p orbitals, and higher superconducting transition temperature (Tc) is possible if more charges are transferred into the BiS2 layers from conducting layer. This work reveals the importance of electron carrier density in the high‐Tc phase and estimated critical current density under pressure upto 1 GPa.