Nowatorskie nadprzewodzące cienkie warstwy na bazie żelaza – techniki wysokociśnieniowe, dynamika wirowa i charakterystyka granic ziaren

Iron-based superconductors (FBS), the second class of high-temperature superconductors alongside copper-based superconductors, have gained interest in basic research and possible applications, e.g., as conductors in high magnetic field coil inserts. This is due to their high critical fields, low anisotropies, and high critical current densities, which allow them to fill the gap in properties and application potential between classic low-temperature superconductors and copper-based superconductors. Here, we plan to develop a unique method for producing new and improved types of thin FBS layers by combining conventional techniques at ambient pressure (CT-AP) (i.e., pulse laser deposition, PLD) and high-pressure techniques through the cooperation of German and Polish groups. We are focusing on two important classes, the so-called 1111 (REFeAsO; RE = rare earth, as a doped family) and 1144 (AeAFe4As4; Ae = Ca, Eu; A = K, Rb as a stoichiometric family). In the case of 1111, new variants will be grown and complete, unambiguous phase diagrams will be established. In the case of 1144, no thin film samples exist yet, but they are highly anticipated and important for fundamental and applied research, such as electrical transport measurements. This is exploration and high risk/high reward. The material aspect of this project involves establishing high-pressure methods for thin film techniques and synthesizing new types of FBS thin films. The physical aspect involves determining phase diagrams (regarding doping and magnetic field) and fundamental constants (penetration depth, coherence length, and their anisotropies), while the engineering aspect involves evaluating the potential for applying these new FBS phases. Few studies have demonstrated the advantages of high-pressure preparation of bulk and single FBS crystals compared to conventional methods, such as controlled phase diagram modification, increased reactivity, evaporation prevention, and enhanced superconducting properties. However, it is necessary to systematically study a range of samples to achieve the intrinsic properties of FBS. High-pressure techniques will be used in several ways in this project: synthesis of highly dense and homogeneous bulk samples and targets, thin film growth, annealing of films and investigation of the high-pressure properties of grown samples. The bulk samples treated under high pressure are targets for the PLD and HP-HTG processes. The successful completion of the project is only possible by combining the expertise in thin film deposition at KIT Karlsruhe and high-pressure methods at IHPP Warsaw within a single doctoral project at each of these institutions. The expected results of this project will be new methods for thin film growth, new Fe-based superconducting phases, complete phase diagrams, a deeper understanding of fundamental and application properties, as well as enhanced European cooperation and education of young scientists.