Rare-earth transition-metal pnictides: Heavy -fermion behavior versus magnetism and superconductivity

在Ce基铁化合物中，Ce4F态的混价或重费米子行为与其他电子相关效应，如磁序、超导电性和自旋密度波(SDW)的形成直接竞争，这些效应导致有趣的材料性质，这些性质严重依赖于化学成分或外部压力等参数。这些关联现象的相互作用将在结构表征良好的单晶样品的基础上，通过同步辐射的角度和自旋分辨光电子(PE)谱来研究。与动量(k矢量)相关的Ce4f和Fe3d衍生带之间的相互作用有望导致所产生的准粒子带的色散和能量分裂，这些准粒子带决定了费米面，并可以通过PE可视化。单晶样品的实验数据将作为温度和化学成分的函数，并将在周期Anderson模型(PAM)的方法中进行讨论，该模型是用非交叉近似(NCA)作为杂质解算器的动力学平均场理论(DMFT)求解的，并将讨论非杂化价带(VB)态的能带结构计算结果。

In Ce-based iron-pnictides, mixed-valent or heavy-fermion behavior of the Ce 4f states is in direct competition to other electron-correlation effects like magnetic order, superconductivity, and spin-density wave (SDW) formation that lead to interesting material properties which depend critically on parameters like chemical composition or external pressure. The interplay of these correlation phenomena will be studied by means of angle and spin-resolved photoelectron (PE) spectroscopy with synchrotron radiation on the basis of structurally well-characterized single-crystalline samples. Momentum (k-vector) dependent interactions between Ce 4f and particularly Fe 3d -derived bands are expected to lead to dispersions and energy-splittings of the resulting quasi-particle bands that determine the Fermi surfaces and may be visualized by means of PE. Experimental data from single-crystalline samples will be taken as a function of temperature and chemical composition and will be discussed within an approach to the periodic Anderson-model (PAM) that is solved by dynamical meanfield theory (DMFT) using non-crossing approximation (NCA) as impurity solver and results of band-structure calculations for the non-hybridized valence-band (VB) states.