Fermi surface nesting induced strong pairing in iron-based superconductors
Fermi surface nesting induced strong pairing in iron-based superconductors
复制标题
费米表面嵌套在铁基超导体中诱导强配对
DOI：
10.1073/pnas.0900469106
复制
发表时间：
2009-05-05
影响因子：
11.1
通讯作者：
Takahashi, T.
中科院分区：
文献类型：
--
作者：
Terashima, K.;Sekiba, Y.;Takahashi, T.
铁磷属元素化物高温超导性的发现，使人们有可能在多能带材料中找到一种非传统的超导机制。费米面（FS）相关的无结超导带隙的观察表明，FS间的相互作用可能在超导配对中起着至关重要的作用。在最佳空穴掺杂的Ba_（0.6）K_（0.4）Fe_（2As）_2中，几乎嵌套的FS口袋上的配对强度同时增强（2Δ/Tc ≥ 7），即，内层的类空穴（α）FS和2个杂化的类电子FS，而外层的类空穴（β）FS的配对仍然很弱（2Δ/Tc = 3.6）。在这里，我们报告说，在电子掺杂的BaFe1.85Co0.15As2，FS嵌套条件从α切换到β FS由于相反的尺寸变化的空穴和电子类FS电子掺杂后。强的对强度（2Δ/Tc_6）也能转变为β FS，表明FS嵌套与超导配对之间存在密切联系，并有力地支持铁基超导体中的FS间配对机制.
The discovery of high-temperature superconductivity in iron pnictides raised the possibility of an unconventional superconducting mechanism in multiband materials. The observation of Fermi-surface (FS)-dependent nodeless superconducting gaps suggested that inter-FS interactions may play a crucial role in superconducting pairing. In the optimally hole-doped Ba0.6K0.4Fe2As2, the pairing strength is enhanced simultaneously (2Δ/Tc≈7) on the nearly nested FS pockets, i.e., the inner hole-like (α) FS and the 2 hybridized electron-like FSs, whereas the pairing remains weak (2Δ/Tc≈3.6) in the poorly nested outer hole-like (β) FS. Here, we report that in the electron-doped BaFe1.85Co0.15As2, the FS nesting condition switches from the α to the β FS due to the opposite size changes for hole- and electron-like FSs upon electron doping. The strong pairing strength (2Δ/Tc≈6) is also found to switch to the nested β FS, indicating an intimate connection between FS nesting and superconducting pairing, and strongly supporting the inter-FS pairing mechanism in the iron-based superconductors.