Possible strain-induced enhancement of the superconducting onset transition temperature in infinite-layer nickelates
Xiaolin Ren, Jiarui Li, Wei-Chih Chen, Qiang Gao, Joshua J. Sanchez, Jordyn Hales, Hailan Luo, Fanny Rodolakis, J. L. McChesney, Tao Xiang, Jiangping Hu, Riccardo Comin, Yao Wang, Xingjiang Zhou, Zhihai Zhu
Abstract
Abstract The mechanism of unconventional superconductivity in correlated materials remains a great challenge in condensed matter physics. The recent discovery of superconductivity in infinite-layer nickelates, as an analog to high- T c cuprates, has opened a new route to tackle this challenge. By growing 8 nm Pr 0.8 Sr 0.2 NiO 2 films on the (LaAlO 3 ) 0.3 (Sr 2 AlTaO 6 ) 0.7 substrate, we successfully raise the superconducting onset transition temperature T c in the widely studied SrTiO 3 -substrated nickelates from 9 K into 15 K, which indicates compressive strain is an efficient protocol to further enhance superconductivity in infinite-layer nickelates. Additionally, the x-ray absorption spectroscopy, combined with the first-principles and many-body simulations, suggest a crucial role of the hybridization between Ni and O orbitals in the unconventional pairing. These results also suggest the increase of T c be driven by the change of charge-transfer nature that would narrow the origin of general unconventional superconductivity in correlated materials to the covalence of transition metals and ligands.