The electrical transport in the pnictides especially the quasiparticle tunnelling and Josephson effects in inhomogeneous superconducting systems can provide information on the symmetry of the order parameter. Different kinds of Josephson junctions with one or two pnictide electrodes were realised and their properties were experimentally studied in detail (e.g., current–voltage characteristics, microwave response, current‐phase relations, dependencies on temperature and external magnetic field). These results were compared to well‐known Josephson junctions and recent theories taking into account the special properties (multiband superconductivity, exotic pairing symmetry) of the pnictides. By combination of two junctions in different crystal directions with different barrier transparencies one forms corner junctions or SQUIDs as phase‐sensitive devices. If the technological problems can be solved the investigations on such devices will finally clear up the symmetry of the pnictides, directly. 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, both established ones and novel ones utilising the special pnictide properties.

We prepared planar hybrid Josephson junctions using Co‐doped BaFe2As2 thin films and polished single crystals as base electrode, sputtered, and subsequently oxidized titanium layers as barrier and a counter electrode from evaporated lead. On all junctions, RCSJ‐like current–voltage characteristics could be observed. The obtained IcRn products at 4.2 K range up to 95μV for thin film junctions and up to 1.15 mV for junctions on single crystals. For most of the junctions, an excess current with variable contribution to the total current could be observed. Unusual temperature dependencies are discussed for the critical and the excess currents, respectively. Investigations of the junctions under microwave irradiation were performed, therein Shapiro steps up to high orders and very clear modulations of the steps could be observed. Additionally, the origin of the excess current is discussed with respect to the microwave dependence. Furthermore, instead of a single junction, a network‐like modulation behavior of the critical current in magnetic fields was observed.

In this study, we have prepared Bi2Sr2CaCu2Ox (BSCCO) nanostructure films by pulsed laser deposition technique (PLD). The structural and optical properties of nanostructured Bi2Sr2CaCu2Ox film were investigated. X-ray diffraction (XRD) studies of the films prepared at 6.5 and 8 J/cm 2 showed that the films are crystalline in nature with orthorhombic phase.Scanning electron microscopy (SEM) investigation confirmed that the deposited film has spherical grains and the mean grain size of the film increased from 150 nm to 250 nm as laser energy density increased from 6.5 to 8 J/cm 2 . The optical energy gap of the film decreased from 2.24 to 1.7eV when the energy density increased. The optoelectronic properties of the Bi2Sr2CaCu2Ox/Si heterojunction photodetector have been investigated. The photodetectors exhibited rectification properties and the ideality factor of the photodetectors deposited 6.5 and 8 J/cm 2 were 2.3 and 4.2, respectively. The on/off ratio of the photodetectors was found to be 761 and 385 for the photodetectors prepared with6.5 and 8 J/cm 2 , respectively. A responsivity of 514 mA/W at 860 nm was found for the photodetector prepared with 6.5 J/cm 2 without using post annealing and/or buffer layer.