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Influence of Residual Resistance Measurements on the Superconducting Transition of Ultra‐High‐Purity Niobium
Author(s) -
Fellmuth B.,
Elefant D.
Publication year - 1988
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221460121
Subject(s) - superconductivity , condensed matter physics , niobium , materials science , residual resistivity , residual , superconducting coherence length , physics , metallurgy , algorithm , computer science
A new surprising phenomenon is discovered investigating the superconducting transitions of ultra‐high‐purity niobium single crystals (reciprocal residual resistance ratio up to 53000). It can be detected that inductively measured transition curves are broadened by more than two orders of magnitude only by the simultaneous influence of the transport current and the external magnetic field ( H a > H 1 c ) applied at measurements of the residual resistance using usual experimental technique. This broadening is caused by a change of the superconducting parameters in a surface layer with a thickness of only some μm. The reproducibility of the phenomenon and the spatial dependence of the superconducting parameter change in the surface layer are carefully investigated. An interpretation of the broadened transition curves is carried out on the basis of the phenomenological Ginzburg‐Landau theory. The results obtained lead to the conjecture that the phenomenon is connected with the transition from the Meissner state to the Shubnikov state in the presence of a transport current.