Strongly correlated superconductivity in a copper-based metal-organic framework with a perfect kagome lattice
Takaaki Takenaka, K. Ishihara, M. Roppongi, Yijie Miao, Yuta Mizukami, T. Makita, Junto Tsurumi, Shun Watanabe, J. Takeya, Minoru Yamashita, Kenji Torizuka, Yoshiya Uwatoko, T. Sasaki, Xing Huang, W. Xu, Daoben Zhu, Ninghu Su, Jinguang Cheng, T. Shibauchi, K. Hashimoto
Abstract
of 0.25 kelvin raises fundamental questions about the nature of electron pairing. Here, we show that Cu-BHT is a strongly correlated unconventional superconductor with extremely low superfluid density. A nonexponential temperature dependence of superfluid density is observed, indicating the possible presence of superconducting gap nodes. The magnitude of superfluid density is much smaller than those in conventional superconductors and follows the Uemura's relation of strongly correlated superconductors. These results imply that the unconventional superconductivity in Cu-BHT originates from electron correlations related to spin fluctuations of kagome lattice.