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Effects of Self-field and Low Magnetic Fields on the Normal-Superconducting Phase Transition

M. C. Sullivan·D. R. Strachan·T. Frederiksen·R. A. Ott·C. J. Lobb
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Abstract

Researchers have studied the normal-superconducting phase transition in the high-$T_c$ cuprates in a magnetic field (the vortex-glass or Bose-glass transition) and in zero field. Often, transport measurements in "zero field" are taken in the Earth's ambient field or in the remnant field of a magnet. We show that fields as small as the Earth's field will alter the shape of the current vs. voltage curves and will result in inaccurate values for the critical temperature $T_c$ and the critical exponents $ν$ and $z$, and can even destroy the phase transition. This indicates that without proper screening of the magnetic field it is impossible to determine the true zero-field critical parameters, making correct scaling and other data analysis impossible. We also show, theoretically and experimentally, that the self-field generated by the current flowing in the sample has no effect on the current vs. voltage isotherms.

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M. C. Sullivan, D. R. Strachan, T. Frederiksen, R. A. Ott, C. J. Lobb. 2005-05-13. Effects of Self-field and Low Magnetic Fields on the Normal-Superconducting Phase Transition. https://doi.org/10.1103/physrevb.72.092507

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