Novel and metastable arsenic free Fe based pnictide superconductors synthesized by reactive molecular beam epitaxy

与铜酸盐的情况相比，铁基超导化合物包含了各种各样的材料。在这里，我们打算用氧化物分子束外延（MBE）生长的单晶外延薄膜来研究不同的镍基材料及其结构、磁性和超导性之间的相互作用。氧化物MBE被用作低温生长（亚稳态）肽的多功能晶体合成工具，因此可以进行广泛的掺杂和取代研究。（注意，在这里，MBE不只是作为已知化合物薄膜应用的一种生长方法）。因此，我们将得到作为化学掺杂（对应于空穴和电子掺杂）和衬底或取代引起的结构畸变的函数的各种超导相图。这项工作将有助于识别新的超导材料系统，并允许系统地了解物理性质对材料成分的依赖。可以将我们在Fe-pnictide体系中使用氧化物MBE掺杂/取代的预期选择总结如下：La（K, Na, Sr, Ca，镧系化合物）O(N)Fe（Ni， d过渡金属）Bi（Sb）。由于其毒性和世界范围内已经存在的结果的数量，我们目前不针对基于as的农药。

Even more than in the case of cuprates, the Fe-based superconducting pnictides encompassa huge variety of materials. Here we intend to investigate the interplay between thedifferent pnictide materials and their structural, magnetic and superconducting propertiesby using single-crystalline epitaxial thin films grown by oxide molecular beam epitaxy(MBE). Oxide MBE is used as a versatile crystal synthesis tool for low-temperature growthof (metastable) pnictides and, thereby, allows extensive doping and substitution studies.(Note that here MBE is not used as a mere growth method for thin film applicationsof known compounds). As a result, we will obtain a variety of superconductivity phasediagrams as a function of chemical doping (corresponding to hole and electron doping),and substrate or substitution induced structural distortions. This work will contribute toidentify new superconducting material systems, and allow to understand systematicallythe dependence of physical properties on material compositions. One can summarizeour intended choice of doping/substitutions by oxide MBE in the Fe-pnictide systems asfollows: La(K, Na, Sr, Ca, lanthanoides)O(N)Fe(Ni, d-transition metals)Bi(Sb). We arecurrently not aiming at the As-based pnictides due to their toxicity and the amount of theworld-wide already existing results.