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    • Keywords


      Critical current; lock-in technique; frequency-dependent resistance

    • Abstract


      V-I characteristics of sintered superconducting pellets of YBa2Cu3O7−δ was measured with a resolution one order of magnitude better than the usual dc techniques employing nanovoltmeters. For this purpose software-based lock-in-amplifier technique was developed and used. A square-wave excitation current was used. The voltage signal was digitized into a time series and Fourier-analysed on a computer in this technique. Our results show a very small frequency-dependent resistance in some samples which are nominally superconducting. These results help in checking the material quality and defining the critical current densities better.

    • Author Affiliations


      Kapil M S Bajaj1 Biswanath Sarkar1 S T Lakshmikumar1 Ravi Mehrotra1

      1. National Physical Laboratory, Dr K. S. Krishnan Marg, New Delhi - 110 012, India
    • Dates

  • Bulletin of Materials Science | News

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      Posted on July 25, 2019

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