Investigation of superconductivity and metamagnetism in single and double layered ruthenates using angle resolved photoelectron spectroscopy

单层和双层Ruthenate是最突出的例子，多个相互作用的竞争导致了电子物质新的有序相的出现。特别是，前者是第一个非常规的p波超导体，而后者则以接近量子临界点和超磁性而闻名。此外，在Ca替代后，这些材料可以被驱动到反铁磁Mott绝缘体状态。尽管理论上和实验上对这些材料一直感兴趣，但从准粒子能带结构图出发，仍然缺乏一幅能够解释如此多复杂基态及其相互关系的收敛图。该项目的目的是利用角分辨光电子能谱--一种提供关于k分辨能带结构的完整信息的实验技术--在整个化学掺杂和温度范围内阐明单层和双层Ruthenate的电子结构。虽然有关Sr2RuO4超导带隙的动量和能带分辨数据将有助于限制目前建议的解释这种材料超导电性的理论方法的数量，但详细的化学掺杂研究应该为巡回顺磁相向反铁磁性相的演化提供最直接的实验证明。当谈到在Ruthenate中观察到的复杂有序现象时，后者对于理解选择性Mott转变和轨道有序化在多大程度上是合适的描述是必要的。

Single- and double-layered ruthenates belong to the most prominent examples, where competition of multiple interactions leads to emergence of novel ordered phases of electronic matter. In particular, the former is the first unconventional p-wave superconductor, while the latter is famous for its proximity to quantum critical point and metamagnetism. Moreover, upon Ca substitution these materials can be driven into an antiferromagnetic Mott insulator state. Despite unceasing theoretical and experimental interest to these materials a convergent picture that would explain such a variety of complex ground states and their interrelation starting from a quasiparticle band structure picture is still missing. The aim of this project is to clarify the electronic structure of single- and double-layer ruthenates in the whole accessible range of chemical doping and temperatures using angle resolved photoelectron spectroscopy—an experimental technique providing a complete set of information on the k-resolved band structure. While momentum and band resolved data on superconducting gap in Sr2RuO4 would help to limit the number of theoretical approaches currently suggested to account for the occurrence of superconductivity in this material, a detailed investigation of chemical doping should provide the most direct experimental demonstration for the evolution of itinerant paramagnet phase into antiferromagnetic one. The latter is necessary to understand to which extent the selective Mott transition and orbital ordering are apt descriptions, when speaking of complex ordering phenomena observed in ruthenates.