Iron-based Superconductors.pptx

Anistropic superconducting gap in iron-based superconductors Xyy I. Experiment arXiv:1105.2232v1 Low-temperature thermal conductance Residual linear term: Optimal doping: x=0.4, fully isotropic gap Wiedemann-Franz law: where arXiv: 1105.2265 In-plane London penetration depth measurement Exponential: fully gap Power-law: nodal gap Away form optimal doping, T dependence of penetration depth changes form exponential to power law behavior, indicates the formation of a nodal gap A circular nodel line appears on the kz=pi plane of the most warping hole pocket. Fermi surface Kz=pi Kz=0.38Pi II. Theory PhysRevLett.106.187003 Due to different height of As and P to the Fe-plane, the Fermi surface differs in these two iron pnictides. In FeAs-based materials, an extra hole pocket appears in M-point. Fermi surface and SC formfactor of LaFeAsO Fermi surface and SC form factor of LaFePO FeSe PRB.81.184512, DHLee