Charnukha A, Post K W, Thirupathaiah S, Pröpper D, Wurmehl S, Roslova M, Morozov I, Büchner B, Yaresko A N, Boris A V, Borisenko S V, Basov D N
Physics Department, University of California-San Diego, La Jolla, CA 92093, USA.
Leibniz Institute for Solid State and Materials Research, IFW, 01069 Dresden, Germany.
Sci Rep. 2016 Jan 5;6:18620. doi: 10.1038/srep18620.
Iron-based superconductors have been found to exhibit an intimate interplay of orbital, spin, and lattice degrees of freedom, dramatically affecting their low-energy electronic properties, including superconductivity. Albeit the precise pairing mechanism remains unidentified, several candidate interactions have been suggested to mediate the superconducting pairing, both in the orbital and in the spin channel. Here, we employ optical spectroscopy (OS), angle-resolved photoemission spectroscopy (ARPES), ab initio band-structure, and Eliashberg calculations to show that nearly optimally doped NaFe0.978Co0.022As exhibits some of the strongest orbitally selective electronic correlations in the family of iron pnictides. Unexpectedly, we find that the mass enhancement of itinerant charge carriers in the strongly correlated band is dramatically reduced near the Γ point and attribute this effect to orbital mixing induced by pronounced spin-orbit coupling. Embracing the true band structure allows us to describe all low-energy electronic properties obtained in our experiments with remarkable consistency and demonstrate that superconductivity in this material is rather weak and mediated by spin fluctuations.
人们发现铁基超导体呈现出轨道、自旋和晶格自由度之间的紧密相互作用，极大地影响了它们的低能电子特性，包括超导性。尽管精确的配对机制仍未确定，但已提出几种候选相互作用来介导轨道和自旋通道中的超导配对。在此，我们采用光谱学（OS）、角分辨光电子能谱（ARPES）、第一性原理能带结构和埃利亚什贝格计算来表明，近最佳掺杂的NaFe0.978Co0.022As在铁基氮化物家族中表现出一些最强的轨道选择性电子关联。出乎意料的是，我们发现在强关联能带中巡游电荷载流子的质量增强在Γ点附近显著降低，并将这种效应归因于明显的自旋轨道耦合引起的轨道混合。采用真实的能带结构使我们能够以显著的一致性描述在我们的实验中获得的所有低能电子特性，并证明这种材料中的超导性相当弱且由自旋涨落介导。
