Unconventional Superconductivity in the BiS2 -Based Layered Superconductor NdO0.71F0.29BiS2

Yuichi Ota, Kozo Okazaki, Haruyoshi Q. Yamamoto, Takashi Yamamoto, Shuntaro Watanabe, Chuangtian Chen, Masanori Nagao, Satoshi Watauchi, Isao Tanaka, Yoshihiko Takano, Shik Shin
2017 Physical Review Letters  
We investigate the superconducting-gap anisotropy in one of the recently discovered BiS_2-based superconductors, NdO_0.71F_0.29BiS_2 (T_c ∼ 5 K), using laser-based angle-resolved photoemission spectroscopy. Whereas the previously discovered high-T_c superconductors such as copper oxides and iron-based superconductors, which are believed to have unconventional superconducting mechanisms, have 3d electrons in their conduction bands, the conduction band of BiS_2-based superconductors mainly
more » ... s of Bi 6p electrons, and hence the conventional superconducting mechanism might be expected. Contrary to this expectation, we observe a strongly anisotropic superconducting gap. This result strongly suggests that the pairing mechanism for NdO_0.71F_0.29BiS_2 is unconventional one and we attribute the observed anisotropy to competitive or cooperative multiple paring interactions.
doi:10.1103/physrevlett.118.167002 pmid:28474948 fatcat:3kbve3sdarg7fi7s5v46nydfwu