Gestość prądu krytycznego i mechanizm kotwiczenia wirów w nadprzewodnikach żelazowych syntezowanych technologią wysokociśnieniową

The newly discovered Iron-Based Superconductors (FBS) have rich physics including magnetic and nematic instabilities, electronic correlations, and quantum phenomena. FBS have been placed as a strong contender for practical application owing to their very high upper critical field (Hc2~100 T), low anisotropy (γ~1-2) and high critical current density (Jc~10^8 A/cm^2). These systems provide the latest platform for high-temperature unconventional superconductivity with record high Tc of 58 K in bulk doped materials and 100 K in special single-layer setups. The recent observation of Majorana zero modes in FBS implies a potentiality for future application in topological quantum calculating. Hence, the new progress in the vortex pinning physics is necessary to approach the fundamental understanding of the electromagnetic properties of High Tc Superconductors (HTS). However, one basic challenging problem of this family is the growth of high-quality single crystals and thin films using Conventional Synthesis Process at ambient pressure (CSP-AP). Due to these reasons, the final agreements on the intrinsic superconducting/vortex properties and pinning mechanism have not been reached yet, and there are many contradictions with their intrinsic properties. To overcome these problems, this project is designed to explore the intrinsic vortex pinning behaviours of HTS through systematic studies of FBS, and its application to understand the Jc properties and anisotropic nature using a unique and rare High-Pressure Technique (HPT) which distinguishes us from other groups around the world that mostly use processing at normal pressure. Almost, all major facilities are available on the IHPP PAN for this project, however, they are not fully utilised. HPT is a unique, rare and sophisticated technique through which a systematic and series of high quality and well-shaped samples are needed to establish the intrinsic properties of FBS. This project also allows to build and develop a successful work team that will focus on the fundamental studies through HPT in Poland. We will design and set-up the high pressure and high temperature chamber applied with Hot-Isostatic Pressure (HIP) system especially devoted for FBS, and also Variable Temperature Insert (VTI) sample holder attached to Cryogen Free High Magnetic Field Facility (CFHMF) (2-350 K, 0-9 T, 0-1.2 GPa) for transport and thermal characterizations. Two challenging families 1111 (REFeAsO; RE: rare earth) and 1144 (AeAFe4As4; Ae = Ca, Eu; A = K, Rb) of FBS will be considered potentially in this project. Firstly, we will emphasis to study of parameter optimization for growing the high quality and large sized single crystals and thin films using High Pressure and High Temperature Synthesis Method (HP-HTS). All prepared samples will be thoroughly characterized by structural, microstructure, transport and magnetic measurements in various magnetic fields, pressure and temperature. These studies will confirm the quality of various samples, superconducting properties and also analyse the various pinning parameters such as pinning force, type of pinning, activation energy, pinning mechanism etc. Experiments using advanced techniques for transport measurements are also planned using high magnetic field facilities available in Europe (https://emfl.eu/) on the selected samples. The combination of these studies will allow to construct the synthesis, superconducting and the extended vortex phase diagram regardless of type of the samples with various parameters. The outcomes of this project will short out the sample issues, and explore the deeper understanding of the intrinsic pinning mechanism and vortex physics of FBS by combining the structural geometry and strong fluctuation state under the shadow of chemical and applied pressure effects. At the end, the results of this project will reliably predict the electromagnetic properties of real superconducting materials and will be appeared in many good international journals. These developed high pressure and characterization setups will establish this team to work independently on many more material systems and field in future that are difficult to achieve at normal pressure. Furthermore, this project will also strengthen the Polish cooperation in this research field and aware that challenging results can be expected using the unique facilities. We will also collaborate with different Polish groups for more advanced characterizations.Po pierwsze, położymy nacisk na badanie optymalizacji parametrów do hodowli wysokiej jakości i dużych monokryształów i cienkich warstw przy użyciu High Metoda syntezy ciśnieniowej i wysokotemperaturowej (HP-HTS). Wszystkie przygotowane próbki zostaną dokładnie scharakteryzowane przez pomiary strukturalne, mikrostrukturalne, transportowe i magnetyczne w różnych polach magnetycznych, ciśnieniu i temperaturze. Badania te potwierdzą jakość różnych próbek, właściwości nadprzewodzące, a także przeanalizują różne parametry przypinania, takie jak siła przypinania, rodzaj przypinania, energia aktywacji, mechanizm przypinania itp. Eksperymenty z użyciem Planowane są również zaawansowane techniki pomiarów transportowych z wykorzystaniem urządzeń o silnym polu magnetycznym dostępnych w w Europie (https://emfl.eu/) na wybranych próbach.