Reproduction of experimental gap structure in LiFeAs based on orbital-spin fluctuation theory: s++-wave, s±-wave, and hole-s±-wave states
Reproduction of experimental gap structure in LiFeAs based on orbital-spin fluctuation theory: s++-wave, s±-wave, and hole-s±-wave states
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基于轨道自旋涨落理论再现 LiFeAs 实验间隙结构：s++ 波、s± 波和空穴 s± 波态
DOI：
10.1103/physrevb.90.035104
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and Volodymyr B. Zabolotnyy
中科院分区：
文献类型：
--
作者：
Tetsuro Saito;Seiichiro Onari;Youichi Yamakawa;Hiroshi Kontani;Sergey V. Borisenko;and Volodymyr B. Zabolotnyy
LiFeAs 与 K 中电子和空穴之间不存在嵌套的现象引起了人们的极大关注，这是理解铁基超导体配对机制的重要线索。在这里，我们基于最近发展的轨道-自旋涨落理论研究了LiFeAs的五轨道模型。研究发现，实验观察到的LiFeAs带隙结构，即配对机制的“指纹”，可以用轨道涨落介导波状态定量再现。具体来说，可以解释在由（）轨道组成的两个小孔袋上观察到的最大间隙，这是轨道涨落介导的超导性的标志。在存在弱自旋涨落的情况下，波隙结构变得更加各向异性。随着自旋涨落的增加，由于轨道和自旋涨落的共同作用，我们获得了“空穴波态”，其中只有轨道构成的大空穴袋的间隙符号反转。这种具有“孔袋之间符号反转”的间隙结构与最近报道的类似。
The absence of nesting between electron and hole pockets in LiFeAs withK attracts great attention, as an important hint to understand the pairing mechanism of Fe-based superconductors. Here, we study the five-orbital model of LiFeAs based on the recently developed orbital-spin fluctuation theories. It is found that the experimentally observed gap structure of LiFeAs, which is a “fingerprint” of the pairing mechanism, is quantitatively reproduced in terms of the orbital-fluctuation-mediated-wave state. Specifically, the largest gap observed on the two small hole pockets composed of () orbitals can be explained, and this is a hallmark of the orbital-fluctuation-mediated superconductivity. The-wave gap structure becomes more anisotropic in the presence of weak spin fluctuations. As the spin fluctuations increase, we obtain the “hole--wave state,” in which only the gap of the large hole pocket made of theorbital is sign reversed, due to the cooperation of orbital and spin fluctuations. This gap structure with “sign reversal between hole pockets” is similar to that recently reported in.