Enhanced superconductivity of Ba0.5K0.5Fe2As2 under surface potassium dosing
Enhanced superconductivity of Ba0.5K0.5Fe2As2 under surface potassium dosing
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表面掺钾条件下Ba0.5K0.5Fe2As2的增强超导性
DOI：
10.1088/1361-648x/aae423
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Feng Donglai
中科院分区：
文献类型：
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作者：
Miao Jin;Niu Xiaohai;Jiang Juan;Peng Rui;Xie Binping;Chen Fei;Xu Haichao;Feng Donglai
表面掺钾已被证明是调节硫系铁系化合物和电子掺杂铁系化合物中电子掺杂和提高超导转变温度的有效方法。然而，表面钾掺杂对空穴掺杂铁基超导体中空穴掺杂和超导电性的影响尚不清楚。在这里，我们对典型的空穴掺杂铁磷灰石化合物Ba0.5K0.5Fe2As2进行了K掺杂，并用原位角度分辨光电子能谱研究了其电子结构。表面K掺杂从Ba0.5K0.5Fe2As2开始，有效地降低了空穴浓度，达到最佳掺杂，提高了超导电性。有趣的是，在最佳掺杂时，超导电性的增强并没有减慢，而且即使在载流子掺杂饱和的情况下，带隙也随着K的掺杂而进一步增加。同时，K值越高，内孔的准粒子相干性越强。我们的结果揭示了Ba1−xKxFe2As2中K掺杂的一种新的散射降低效应，它与载流子掺杂效应协同作用，增强了超导电性。
Surface potassium dosing has been proven to be an effective method in tuning the electron doping and enhancing the superconducting transition temperatures in both iron chalcogenides and electron doped iron pnictides. However, it is not clear how surface potassium dosing affects the hole doping and superconductivity in hole doped Fe-based superconductors. Here we performed K-dosing on Ba0.5K0.5Fe2As2, a prototypical hole-doped iron pnictide compound, and explored the electronic structure by in situ angle-resolved photoemission spectroscopy measurements. Starting from the slightly over-doped Ba0.5K0.5Fe2As2, surface K-dosing effectively reduces the hole concentration towards optimal doping and enhances the superconductivity. Intriguingly, the enhancement of superconductivity does not slow down at optimal doping, and the gap further increases with K dosing even when the carrier doping effect is saturated. Meanwhile, the quasiparticle coherence of the inner hole pockets is enhanced by higher K dosing. Our results uncover a novel scattering-reduction effect of K-dosing in Ba1−xKxFe2As2, which collaborates with the carrier doping effect and enhances superconductivity.