PTCDA Molecular Monolayer on Pb Thin Films: An Unusual π -Electron Kondo System and Its Interplay with a Quantum-Confined Superconductor

• Published in: Physical review letters 2021-10, Vol.127 (18), p.186805-186805, Article 186805
• Main Authors: Lu, Shuangzan, Nam, Hyoungdo, Xiao, Penghao, Liu, Mengke, Guo, Yanping, Bai, Yusong, Cheng, Zhengbo, Deng, Jinghao, Li, Yanxing, Zhou, Haitao, Henkelman, Graeme, Fiete, Gregory A., Gao, Hong-Jun, MacDonald, Allan H., Zhang, Chendong, Shih, Chih-Kang
• Format: Article
• Language: English
• Subjects: Charge transfer; Hybrid systems; Magnetic moments; Magnetism; Molecular orbitals; Monolayers; Pi-electrons; Playgrounds; Quantum confinement; Superconductivity; Superlattices; Thin films
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.127.186805

The hybridization of magnetism and superconductivity has been an intriguing playground for correlated electron systems, hosting various novel physical phenomena. Usually, localized d or f electrons are central to magnetism. In this study, by placing a PTCDA (3,4,9,10-perylene tetracarboxylic dianhydride) molecular monolayer on ultrathin Pb films, we built a hybrid magnetism/superconductivity ( M / SC ) system consisting of only s p electronic levels. The magnetic moments reside in the unpaired molecular orbital originating from interfacial charge transfers. We reported distinctive tunneling spectroscopic features of such a Kondo screened π electron impurity lattice on a superconductor in the regime of TK ≫ Δ, suggesting the formation of a two-dimensional bound states band. Moreover, moiré superlattices with tunable twist angle and the quantum confinement in the ultrathin Pb films provide easy and flexible implementations to tune the interplay between the Kondo physics and the superconductivity, which are rarely present in M / SC hybrid systems.