Variation of FeAs-superconductors through replacement of As by Si or Ge and Fe by Co or Ni

近年来，人们对铁磷属化合物的结构、磁性、组成与超导性能之间的关系进行了深入的研究。而空穴或电子掺杂是一个非常重要的策略，以诱导这些化合物的超导性，没有尝试的直接电荷载流子掺杂的FeAs层中的取代在作为网站。因此，我们计划研究是否掺杂p-元素，如Si或Ge在As网站可以诱导超导性的FeAs基化合物，以及这种取代的结构稳定性和磁有序的影响。此外，在Fe/Co（Ni）和As/Si（Ge）同时置换过程中，可以预期形成具有孤立FeAs和Ni（Co）Ge（Si）层的新化合物。不同的方法将被应用于所需相的制备，例如。G.基于在密闭容器中高温下的固态反应。获得高质量的大单晶体用于进一步的研究将是我们工作的一个重要任务。在这些系统中发现新的有趣材料的机会预计非常高。

Recently, superconducting iron pnictides have been studied intensively with respect to relationships between their structures, magnetism, composition and superconducting properties. Whereas the hole or electron doping is a very important strategy to induce superconductivity in these compounds, no attempts of direct charge carrier doping by substitution at the As sites in the FeAs layer have been made. Therefore, we plan to study whether doping with p-element such as Si or Ge at the As site can induce superconductivity in FeAs-based compounds as well as the influence of such substitutions on the structure stability and on magnetic ordering. Besides, during simultaneous Fe/Co(Ni) and As/Si(Ge) substitution the formation of new compounds with isolated FeAs and Ni(Co)Ge(Si) layers can be expected. Different methods will be applied for the preparation of the desired phases, e. g. based on solid-state reactions at high temperatures in closed containers. Obtaining highquality large single crystals for further investigations will be an important task of our work. The chances to discover new interesting materials in these systems are expected to be very high.