Laboratório Nacional de Luz Síncrotron, 13083-970 Campinas, SP, Brazil.
Phys Rev Lett. 2011 Dec 23;107(26):267402. doi: 10.1103/PhysRevLett.107.267402. Epub 2011 Dec 20.
The Fe K x-ray absorption near edge structure of BaFe(2-x)Co(x)As(2) superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides experimental support to previous ab initio calculations in which the extra Co electron is concentrated at the substitute site and do not change the electronic occupation of the Fe ions. Superconductivity may emerge due to bonding modifications induced by the substitute atom that weakens the spin-density-wave ground state by reducing the Fe local moments and/or increasing the elastic energy penalty of the accompanying orthorhombic distortion.
研究了 BaFe(2-x)Co(x)As(2) 超导体的 Fe K 边 X 射线吸收近边结构。用 Co 取代时，该边的形状和能量位置没有明显变化。这一结果为以前的从头计算提供了实验支持，即在从头计算中，额外的 Co 电子集中在取代位置，而不改变 Fe 离子的电子占据。超导电性可能是由于取代原子引起的键合修饰而产生的，这种修饰通过降低 Fe 局域磁矩和/或增加伴随的正交畸变的弹性能量惩罚来削弱自旋密度波基态。
