Observation of gapped phases in potassium-doped single-layer p -terphenyl on Au (111)

作者：Mingqiang Ren, Wu-Yu Chen, Q. Liu, C. Chen, Yanjun Qiao, Y. J. Chen, G. Zhou, Zhaohui Li, Tiancheng Zhang, Y. J. Yan, Donglai Feng · 发表于：Physical review. B./Physical review. B · 年份：2019 · DOI：10.1103/physrevb.99.045417 · 被引用次数：12 · 研究领域：Physics of Superconductivity and Magnetism、Surface Chemistry and Catalysis、Advanced Chemical Physics Studies

Recently, signatures of high-Tc superconductivity observed in potassium (K)-doped $p$-terphenyl $({\mathrm{C}}_{18}{\mathrm{H}}_{14})$ have sparked people's interest in phenyl-based materials. Here we report a low-temperature scanning tunneling microscopy/spectroscopy study on K-doped single-layer $p$-terphenyl films grown on Au (111) substrate. We observe several ordered phases with different morphologies and electronic behavior, in two of which a clear low-energy gap of about 11 meV opens below 50 K. In particular, the gap shows no obvious response to a magnetic field up to 11 T, which excludes the possibility that it is a superconducting gap. Such gapped phases are rarely (if ever) observed in hydrocarbon molecular crystals; several candidates for the origin are discussed. Our work also paves the way for fabricating conducting two-dimensional hydrocarbon materials, which would provide a platform for searching emergent phenomena.