Spin-density wave in pnictides: Excitonic instability, dynamics, and transport

我们的总体目标是更好地了解铁多肽的物理性质。最近发现，其中几种化合物在非常高的温度下会变成超导。它们在正常导电状态下的磁性、结构和输运(传导)性质也是非常规的。例如，它们形成了反铁磁性金属，而另一类重要的高温超导体--铜酸盐则形成了反铁磁性绝缘体。由于磁起伏被认为是超导相互作用的中介，因此磁性质对于理解超导也是至关重要的。在这个项目的第一部分，我们将研究磁性和晶格结构的相互作用，特别是关于它们的动力学。已知磁性和结构性质是耦合的，但具体机制仍不清楚。在第二部分中，我们将考虑电荷和能量的非常规输运。我们将计算电导率、热电势和反常霍尔效应。在这两个部分中，我们将讨论各种多肽化合物之间的差异，特别是取代稀土离子的影响。

Our overall goal is to better understand the physical properties of the iron pnictides. Several of these compounds have recently been found to become superconducting at remarkably high temperatures. Their magnetic, structural, and transport (conduction) properties in the normal-conducting state are also unconventional. For example, they form antiferromagnetic metals, in contrast to the other important family of high-temperature superconductors, the cuprates, which form antiferromagnetic insulators. The magnetic properties are also crucial for the understanding of superconductivity since magnetic fluctuations are thought to mediate the superconducting interaction. In the first part of the project, we will study the interplay of magnetism and lattice structure, in particular concerning their dynamics. Magnetism and structural properties are known to be coupled but the detailed mechanism is still unclear. In the second part we will consider the unconventional transport of charge and energy. We will calculate the conductivity, the thermopower, and the anomalous Hall effect. In both parts we will address the differences between the various pnictide compounds, in particular the effects of substituting the rare-earth ions.