Superconductivity in under-doped La_2−xSr_xCuO₄ under pressure

Abstract

The out-of-plane resistivity (ρ_c) has been measured in under-doped La_2−xSr_xCuO₄ 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.