Investigations of key issues on the reproducibility of high- T c superconductivity emerging from compressed La3Ni2O7

Signatures of superconductivity near 80 K have recently been discovered in single crystals of La3Ni2O7 under pressure, which makes it a new candidate for high-temperature superconductors dominated by 3d transition elements, following the cuprate and iron-pnictide superconductors. However, there are several critical questions that have been perplexing the scientific community: (1) What factors contribute to the inconsistent reproducibility of the experimental results? (2) What is the fundamental nature of pressure-induced superconductivity: bulk or nonbulk (filamentary-like)? (3) Where is the superconducting phase located within the sample if it is filamentary-like? (4) Is the oxygen content important for the…