Pressure enhanced superconductivity at 10 K in La doped EuBiS₂F

Abstract

We have investigated the effect of La doping and high pressure on superconducting properties of EuBiS₂F, which is a newly discovered superconducting material (T_c ~ 0.3 K) (Zhai et al (2014) Phys. Rev. B 90 064518). An enhancement of T_c to 2.2 K is observed in Eu0.5La0.5BiS2F. Upon application of pressure T_c is further enhanced up to ~10 K (P = 2.5 GPa). Eu_0.5La_0.5BiS₂F is semiconducting down to 3 K. The onset of a superconductivity-like feature is seen at 2.2 K at ambient pressure. At a pressure above 1.38 GPa, the T_c^onset remains invariant at 10 K but the T_c (ρ = 0) is increased to above 8.2 K. There is a possible crystallographic transformation by application of pressure from a structure of low T_c to a structure corresponding to high T_c.