High-T_c Phase of PrO_(0.5)F_(0.5)BiS_2 single crystal induced by uniaxial pressure

摘要

We demonstrated a pressure-induced phase transition from a low-T_c phase (3.5 K) to a high-T_c phase (8.7 K) in single crystalline PrO_(0.5)F_(0.5)BiS_2. The high-T_c phase is easily observed even at 0.7 GPa by uniaxial pressure obtained from a geometric effect of a single crystal with an extremely thin thickness. For this phase transition, superconducting anisotropy and the coherence length along the c axis change from γ = 20 to 9.3 and from ζ_c = 0.56 to 0.71 nm, respectively. It is suggested that a shrinkage in the c lattice constant by applied uniaxial pressure enhances the three dimensionality in the superconducting state.