Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors
Identifying the 'fingerprint' of antiferromagnetic spin fluctuations in iron pnictide superconductors
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DOI：
10.1038/nphys3187
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发表时间：
2014-02
期刊：
影响因子：
19.6
通讯作者：
M. Allan;Kyungmin Lee;Andreas W. Rost;Mark H. Fischer;F. Massee;K. Kihou;Chul-Ho Lee;A. Iyo;H. Eisaki;T. Chuang;J. C. Davis;Eun-Ah Kim
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文献类型：
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作者：
M. Allan;Kyungmin Lee;Andreas W. Rost;Mark H. Fischer;F. Massee;K. Kihou;Chul-Ho Lee;A. Iyo;H. Eisaki;T. Chuang;J. C. Davis;Eun-Ah Kim
铁基高T_c超导体中的库珀配对通常被认为涉及玻色涨落。其中包括反铁磁性自旋涨落和声子放大的d轨道涨落。任何这样的电子-玻色子相互作用都应该改变电子的“自身能量”，然后通过随后对电子动量和寿命的能量依赖性的改变而变得可探测到。在这里，我们介绍了一种理论和实验相结合的方法，旨在通过测量铁基超导体的自能效应来识别其相关涨落。我们在生命中使用准粒子干涉(QPI)成像技术，揭示了沿Fe-Fe(带间散射)方向聚焦的强动量空间各向异性自能特征，这是生命自旋涨落集中的地方。这些效应在能量上与通常与库珀配对相互作用有关的态密度N(欧米伽)的微扰相吻合。我们发现，所有测量到的现象都包含由反铁磁性自旋涨落引起的自能的QPI“指纹”，从而将它们区分为主要的电子-玻色子相互作用。
Cooper pairing in the iron-based high-Tc superconductors is often conjectured to involve bosonic fluctuations. Among the candidates are antiferromagnetic spin-fluctuations and d-orbital fluctuations amplified by phonons. Any such electron-boson interaction should alter the electron's `self-energy', and then become detectable through consequent modifications in the energy dependence of the electron's momentum and lifetime. Here we introduce a theoretical/experimental approach aimed at identifying the relevant fluctuations of iron-based superconductors by measuring effects of their self-energy. We use quasiparticle interference (QPI) imaging techniques in LiFeAs to reveal strongly momentum-space anisotropic self-energy signatures that are focused along the Fe-Fe (interband scattering) direction, where the spin fluctuations of LiFeAs are concentrated. These effects coincide in energy with perturbations to the density-of-states N(\omega) usually associated with the Cooper pairing interaction. We show that all the measured phenomena comprise the predicted QPI `fingerprint' of a self-energy due to antiferromagnetic spin-fluctuations, thereby distinguishing them as the predominant electron-boson interaction.