Kostin A, Sprau P O, Kreisel A, Chong Yi Xue, Böhmer A E, Canfield P C, Hirschfeld P J, Andersen B M, Davis J C Séamus
Department of Physics, Cornell University, Ithaca, NY, USA.
CMPMS Department, Brookhaven National Laboratory, Upton, NY, USA.
Nat Mater. 2018 Oct;17(10):869-874. doi: 10.1038/s41563-018-0151-0. Epub 2018 Sep 3.
Strong electronic correlations, emerging from the parent Mott insulator phase, are key to copper-based high-temperature superconductivity. By contrast, the parent phase of an iron-based high-temperature superconductor is never a correlated insulator. However, this distinction may be deceptive because Fe has five actived d orbitals while Cu has only one. In theory, such orbital multiplicity can generate a Hund's metal state, in which alignment of the Fe spins suppresses inter-orbital fluctuations, producing orbitally selective strong correlations. The spectral weights Z of quasiparticles associated with different Fe orbitals m should then be radically different. Here we use quasiparticle scattering interference resolved by orbital content to explore these predictions in FeSe. Signatures of strong, orbitally selective differences of quasiparticle Z appear on all detectable bands over a wide energy range. Further, the quasiparticle interference amplitudes reveal that [Formula: see text], consistent with earlier orbital-selective Cooper pairing studies. Thus, orbital-selective strong correlations dominate the parent state of iron-based high-temperature superconductivity in FeSe.
源于母体莫特绝缘体相的强电子关联是铜基高温超导的关键。相比之下，铁基高温超导体的母体相从来都不是关联绝缘体。然而，这种区别可能具有欺骗性，因为铁有五个活跃的d轨道，而铜只有一个。理论上，这种轨道多重性可以产生洪德金属态，其中铁自旋的排列抑制了轨道间的涨落，产生了轨道选择性的强关联。与不同铁轨道m相关的准粒子的光谱权重Z应该会有很大差异。在这里，我们利用通过轨道成分分辨的准粒子散射干涉来探索FeSe中的这些预测。在很宽的能量范围内，所有可检测能带都出现了准粒子Z的强的、轨道选择性差异的特征。此外，准粒子干涉振幅表明[公式：见正文]与早期的轨道选择性库珀配对研究一致。因此，轨道选择性强关联主导了FeSe中铁基高温超导的母体态。
