1210.4619 (Wei Li et al.)

Superconductivity in a single layer alkali-doped FeSe: a weakly coupled
two-leg ladder system    [PDF]

Wei Li, Hao Ding, Pengfei Zhang, Peng Deng, Kai Chang, Ke He, Shuaihua Ji, Lili Wang, Xucun Ma, Jian Wu, Jiang-Ping Hu, Qi-Kun Xue, Xi Chen

We prepare single layer potassium-doped iron selenide (110) film by molecular beam expitaxy. Such a single layer film can be viewed as a two-dimensional system composed of weakly coupled two-leg iron ladders. Scanning tunneling spectroscopy reveals that superconductivity is developed in this two-leg ladder system. The superconducting gap is similar to that of the multi-layer films. However, the Fermi surface topology given by first-principles calculation is remarkably different from that of the bulk materials. Our results suggest that superconducting pairing is very short-ranged or takes place rather locally in iron-chalcogenides. The superconductivity is most likely driven by electron-electron correlation effect and is insensitive to the change of Fermi surfaces.

View original: http://arxiv.org/abs/1210.4619