Preparation and crystal growth of superconducting and magnetic rare earth-transition metal oxypnictides and alkali / earth alkali iron arsenides

我们进行了系统的研究，旨在了解和优化铁多肽及其相关材料的生长机理。我们的广谱晶体生长技术将被用来实现对基本生长参数的一般了解，评估每种技术对不同类型的晶体的潜力，并获得大的单晶。基于这些结果，我们将合成在结构、化学计量比和尺寸方面进行优化的材料，这将允许推断这些材料的一般物理性质。具体地说，我们采用了Snand自熔剂生长，不同的布里奇曼生长技术，以及高Ar压力下的浮区生长。此外，我们将在明确定义的材料的基础上，详细研究缺陷和无序的作用。这项工作将把我们的项目BE1749/12转移到SPP1458，并继续我们的工作，其中我们成功地建立了高压炉，并成功地生长了AFeAs(A=Li，Na)、Co和K掺杂BFe2As2(B=Ba，Ca，Sr)和Fe(Se，Te)单晶以及高质量的REOFeAs-多晶(RE=稀土)掺杂系列。所有样品都将通过各种技术进行详细的分析和表征，并将通过结构、磁性、输运和热力学研究来研究电子相图。此外，样品将被提供给优先计划中的不同群体。

We apply a systematic study aiming at understanding and optimizing the growth mechanism of iron pnictides and related materials. Our very broad spectrum crystal growth techniques will be used to achieve a general understanding of the essential growth parameters, to assess the potential of each technique for the different pnictide classes and to obtain large single crystals. Based on these results, we will synthesize materials optimized regarding structure, stoichiometry, and size, which will allow deducing the generic physical properties of these materials. To be specific, we apply growth from Snand self-flux, different Bridgman-growth techniques, and floating-zone growth under high Ar pressure. In addition, we will study in detail the role of defects and disorder based on well-defined materials. This work shall transfer our project BE1749/12 into the SPP 1458 and continue our work in which the set-up of a high pressure furnace was granted and where we successfully grew AFeAs (A = Li,Na), Co- and K-doped BFe2As2 (B = Ba,Ca,Sr) , and Fe(Se,Te) single crystals as well as high-quality REOFeAs-polycrystalline (RE = rare earth) doping series. All samples will be analyzed and characterized in detail by various techniques and the electronic phase diagrams will be investigated by means of structure, magnetic, transport, and thermodynamic studies. In addition, the samples will be provided to different groups in the priority program.