Identification of superconductivity in bilayer nickelate La3Ni2O7 under high pressure up to 100 GPa
Jing Li, Di Peng, Peiyue Ma, Hengyuan Zhang, Zhenfang Xing, Xing Huang, Chaoxin Huang, Mengwu Huo, De‐Yuan Hu, Zixian Dong, Xiang Chen, Tao Xie, Hongliang Dong, Hualei Sun, Qiaoshi Zeng, Ho‐kwang Mao, Meng Wang
Abstract
ABSTRACT Identification of superconductivity in the Ruddlesden-Popper phases of nickelates under high pressure remains challenging. Here, we report a comprehensive study of the crystal structure, electrical resistance, and Meissner effect in single crystals of bilayer nickelate La3Ni2O7 under hydrostatic pressures up to 104 GPa. Using high-pressure X-ray diffraction, we observe a structural transition from an orthorhombic to a tetragonal phase above 40 GPa. Superconductivity emerges with a maximum onset transition temperature Tconset of 83 K at 18.0 GPa, accompanied by zero resistance. The superconducting phase is gradually suppressed and vanishes above 80 GPa, forming a right-triangle-like superconducting region. Direct-current magnetic susceptibility measurements demonstrate the Meissner effect and reveal a superconducting volume fraction of ∼41% at 22.0 GPa and 20 K, confirming the bulk nature of superconductivity in La3Ni2O7. Our results highlight the intricate relationship between superconductivity, oxygen content, and structural transitions in this material.