Josephson effects at iron pnictides - phase-sensitive experiments

在非均匀超导系统中，将研究磷属元素化物中的电输运，特别是准粒子隧穿和约瑟夫森效应。序参量的对称性将被确定，约瑟夫森行为的后果将被讨论。将实现不同种类的具有磷族元素化物电极的约瑟夫森结，包括与已知的低和高Tc超导体相比的新类型，并且将详细地实验研究它们的性质。这些调查将导致更好地了解的pnictides的基本属性，以及对pnictides在超导电子学和传感器应用中的应用潜力的现实判断。该项目的跨学科方向导致与化学和材料科学团体（多晶样品，单晶和不同磷属元素化物的薄膜）的强烈互动。他们的磷属元素化合物样品将用于本项目中制备不同类型的约瑟夫森结（例如，具有传统s波超导体的一个电极的混合结，新型相敏角结，两个电极都是磷属元素化合物超导体的全磷属元素化合物结）。实现的结的实验特性将进行分析（例如，电流电压特性，微波响应，电流physe关系，温度和外部磁场的依赖关系），并考虑到pnictides的特殊性能，著名的约瑟夫森结和新的理论进行比较。通过这种方式，将磷属元素化合物样品的重结晶和制备过程的进一步优化的重要参数反馈给制备组。与理论小组合作，将改进对实验结果的解释。SPP内的网络将通过与其他组的实验结果（关于配对的对称性，跨晶界的电流传输，平面FeSe薄膜隧道结的测量）的比较以及对其他组（例如THz响应和发射）中本项目中制备的结的额外研究来强制。

The electrical transport in the pnictides especially the quasiparticle tunneling and Josephson effects will be studied in inhomogeneous superconducting systems. The symmetry of the order parameter will be determined and the consequences for the Josephson behaviour will be discussed. Different kinds of Josephson junctions with pnictide electrodes including new types in comparison to the known low and high Tc superconductors will be realized and their properties will be experimentally studied in detail. These investigations will lead to a better understanding of fundamental properties of the pnictides as well as to a realistic judgement on the potential for applications of pnictides in superconducting electronics and sensor applications. The interdisciplinary orientation of the project leads to a strong interaction with chemical and materials science groups (polycrystalline samples, single crystals and thin films of different pnictides). Their pnictide samples will be used in this project to prepare different kinds of Josephson junctions (e.g. hybrid junctions with one electrode of a conventional s-wave superconductor, new kinds of phase-sensitive corner junctions, all-pnictide junctions where both electrodes are pnictide superconductors). Experimental properties of the realized junctions will be analyzed ( e.g. currentvoltage characteristics, microwave response, current-physe relations, dependencies on temperature and external magnetic field) and compared to well-known Josephson junctions and new theories taking into account the special properties of the pnictides. In this way important parameters to characterise the pnictide samples and for further optimization of the preparation process will be give back to the preparation groups. In cooperation with theory groups the interpretation of the experimental results will be improved. The network within the SPP will be forced by the comparison to experimental results from other groups (regarding the symmetry of the pairing, the current transport across grain boundaries, measurements on planar FeSe thin film tunnel junctions) and additional investigations on the junctions prepared in this project in other groups (e.g. THz response and emission).