Superconductivity in under-doped La2−Sr CuO4 under pressure

Abstract The out-of-plane resistivity ( ρ c ) has been measured in under-doped La 2− x Sr x CuO 4 under pressure to investigate the nature of the superconducting transition. The antiferromagnetic insulating sample with x =0.020 did not show superconductivity even under pressure. However, in the non-superconducting samples with x =0.035 and 0.045, an appreciable but incomplete drop of ρ c was observed with lowering temperature and increasing pressure. The drop of ρ c under pressure suggests the existence of the intrinsic phase separation or inhomogeneity around x ∼0.05.