Seminar of International Laboratory of High Magnetic Fields and Low Temperatures PAS
ul. Gajowicka 95, sala seminaryjna (nowy budynek, II piętro)
Investigation of the intra- and inter-granular properties of superconducting Y(Ca)BCO system
dr Krastyo Buchkov
Department of Low Temperature Physics, Institute of Solid State Physics, Bulgarian Academy of Sciences, Sofia, Bulgaria
The application of various chemical substitutions for the high-temperature superconductors (HTSC) is widely used for exploring and modification of their properties. The partial substitution of Ca2+ for Y3+ in the primary system YBCO affects significantly the crystal structure, morphology, charge balance and carrier concentration in CuO2 planes. The use of this substitution gives opportunity for detailed exploration of the properties of YBCO in the over-doped region of the parabolic doping phase diagram. The presented results summarize structural, electrical and magnetic investigations of Y(Ca)BaCuO with different level of substitution and doping. The analysis is focused in intra- and inter-granular scale on important parameters as: irreversibility line, vortex dynamics, Bean-Livingston surface barrier, diamagnetic screening, inter-granular connectivity and AC magnetic response. The AC magnetic response is investigated in details via combined analysis of the fundamental and 3rd harmonic components of the AC magnetic susceptibility. Part of the seminar also will include brief presentation of some preliminary investigations on iron-based superconductors from chalcogenide family (FeSe1-xTex) performed in Low temperature physics department at ISSP-BAS and the International Laboratory of High Magnetic Fields and Low Temperatures.
