High-transition-temperature (high-Tc) superconductivity in cuprates has been discovered for more than three decades, but the underlying mechanism remains a mystery. Cuprates are the only unconventional superconducting family that hosts bulk superconductivity with Tcs above the liquid nitrogen boiling temperature at 77 Kelvin. We found superconductivity in single crystals of La3Ni2O7 grown by the high-pressure floating zone method with a maximum Tc of 80 K at pressures between 14.0-43.5 gigapascals. Our collaborators have confirmed the high Tc superconductivity on our samples independently. The superconducting phase under high pressure exhibits an orthorhombic structure of Fmmm space group with the 3dx2-y2 and 3dz2 orbitals of Ni cations strongly mixing with oxygen 2p orbitals. Density functional theory calculations suggest the superconductivity emerges coincidently with the metallization of the σ-bonding bands under the Fermi level, consisting of the 3dz2 orbitals with the apical oxygens connecting Ni-O bilayers. The recent ARPES and infrared measurements are consistent with our theoretical expectations. Thus, the discoveries not only reveal important clues for the high-Tc superconductivity in this Ruddlesden-Popper double-layered perovskite nickelates but also provide a new family of compounds to investigate the high-Tc superconductivity mechanism. 报告人简介：王猛，中山大学物理学院教授、博士生导师，现任中山大学物理学院副院长、广东省磁电物性分析与器件重点实验室副主任、物理学院中子科学与技术中心主任。王猛教授本科毕业于吉林大学物理学院，博士毕业于中国科学院物理研究所超导国家重点实验室，之后在加州大学伯克利分校物理系开展博士后研究工作。研究兴趣包括非常规超导材料和量子磁性材料的物性及机理研究，研究方法包括材料生长、中子散射、高压技术等，推动并参与中国首台高能非弹性中子散射飞行时间谱仪建设。王猛教授已发表论文70余篇，包括Nature、Nature Physics、Nature Communications、Physical Review Letters、Physical Review B等杂志，是Science China-PMA杂志青年编委，长期担任Nature、Nature Physics、Physical Review Letters等杂志审稿人。 |
