Thermal Fluctuations in YBCO Thin Film on MgO Substrate

M. Chrobak a, W.M. Wocha, G. Szwachtab,c, R. Zalecki a, Ł. Gondek a, A. Kołodziejczyk a and J. Kusiński b aSolid State Physics Department, Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland bDepartment of Surface Engineering and Materials Characterization, Faculty of Metals Engineering and Industrial Computer Science, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland cAcademic Centre for Materials and Nanotechnology, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow, Poland

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The c-axis orientation YBa2Cu3Oδ thin film was prepared directly on MgO substrate by the pulse laser deposition. The thickness of the film was 170 nm. The superconducting critical temperature was Tc50% = 89 K and the width of superconducting transition was ΔT = 1.6 K. Temperature dependence of the critical current of the film was obtained from the temperature dependences of the imaginary part of the AC susceptibility using the Bean model. The critical current density was Jc = 1.2×107 A/cm2 at 77 K in the self field. The critical exponents were calculated for several values of the DC applied magnetic field using the temperature dependences of magnetoresistivity. The thermal fluctuations in vicinity of the critical temperature were analysed.

DOI: 10.12693/APhysPolA.126.A-88 PACS numbers: 74.72.-h, 74.78.-w, 74.40.-n, 74.62.-c