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arXiv 1206.4595cond-mat.supr-concond-mat.str-el
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铁磷属元素化物超导体中库仑关联变化的直接探讨

A direct probe of the variability of Coulomb correlation in Fe-pnictide superconductors

P. Vilmercati, C. Parks Cheney, F. Bondino, E. Magnano, M. Malvestuto, M. A. McGuire, A. S. Sefat, B. C. Sales, D. Mandrus, D. J. Singh, M. D. Johannes, N. Mannella

摘要:

利用芯-价-价(CVV)俄歇谱研究了铁磷属元素化物超导体价带中空穴间的库仑排斥。通过比较两个空穴的最终状态谱的单粒子态密度的密度泛函理论计算,我们提取的电子相关性,存在于这些系统中的措施。我们的结果表明,库仑排斥是高度屏蔽,可以肯定地认为是弱的。我们还发现,有1111和122家庭之间的差异,甚至一个小的变化作为掺杂的函数,x,在Ba(Fe 1 xCox)2As 2。讨论了基于动力学平均场论的模型和第一性原理计算中所用的现场库仑参数U与所得到的空穴-空穴库仑排斥力的关系,并建立了有效值的上限.我们的结果对基于模型的相图施加了严格的限制

英文摘要:

We use core-valence-valence (CVV) Auger spectra to probe the Coulomb repulsion between holes in the valence band of Fe pnictide superconductors. By comparing the two-hole final state spectra to density functional theory calculations of the single particle density of states, we extract a measure of the electron correlations that exist in these systems. Our results show that the Coulomb repulsion is highly screened and can definitively be considered as weak. We also find that there are differences between the 1111 and 122 families and even a small variation as a function of the doping, x, in Ba(Fe1 xCox)2As2. We discuss how the values of the hole-hole Coulomb repulsion obtained from our study relate to the onsite Coulomb parameter "U" used in model and first principles calculations based on dynamical mean field theory, and establish an upper bound for its effective value. Our results impose stringent constraints on model based phase diagrams

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