Department of Physics and Astronomy, University of British Columbia, Vancouver, Canada.
Phys Rev Lett. 2012 Aug 17;109(7):077001. doi: 10.1103/PhysRevLett.109.077001. Epub 2012 Aug 13.
The role of Co substitution in the low-energy electronic structure of Ca(Fe(0.944)Co(0.056))(2)As(2) is investigated by resonant photoemission spectroscopy and density-functional theory. The Co 3d state center of mass is observed at 250 meV higher binding energy than that of Fe, indicating that Co possesses one extra valence electron and that Fe and Co are in the same oxidation state. Yet, significant Co character is detected for the Bloch wave functions at the chemical potential, revealing that the Co 3d electrons are part of the Fermi sea determining the Fermi surface. This establishes the complex role of Co substitution in CaFe(2)As(2) and the inadequacy of a rigid-band shift description.
通过共振光电子能谱和密度泛函理论研究了 Co 取代在 Ca(Fe(0.944)Co(0.056))(2)As(2) 的低能电子结构中的作用。观察到 Co 3d 态质心的结合能比 Fe 高 250 meV，表明 Co 具有一个额外的价电子，Fe 和 Co 处于相同的氧化态。然而，在化学势处的 Bloch 波函数中检测到显著的 Co 特征，这表明 Co 3d 电子是决定费米面的费米海中的一部分。这确立了 Co 取代在 CaFe(2)As(2)中的复杂作用，以及刚性带移描述的不充分性。
