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

单层和双层红酸盐是最突出的例子，其中多种相互作用的竞争导致电子物质的新有序相的出现。特别是前者是第一个非常规的p波超导体，而后者则以其接近量子临界点和超磁性而闻名。此外，在Ca取代后，这些材料可以被驱动成反铁磁莫特绝缘体状态。尽管对这些材料的理论和实验兴趣不断，但从准粒子带结构的角度出发，仍然没有一个收敛的图像来解释如此多种复杂的基态及其相互关系。本项目的目的是利用角分辨光电子能谱——一种提供完整的k分辨能带结构信息的实验技术，在化学掺杂和温度的整个可达范围内阐明单层和双层鲁酸盐的电子结构。虽然Sr2RuO4中超导间隙的动量和能带解析数据将有助于限制目前提出的解释该材料中超导现象的理论方法的数量，但对化学掺杂的详细研究应该为流动顺磁相向反铁磁相的演变提供最直接的实验证明。后者对于理解选择性莫特跃迁和轨道有序在何种程度上是恰当的描述是必要的，当谈到在钌酸盐中观察到的复杂有序现象时。

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.