Plastic Deformation and Superconductivity in Lead, Indium, and Thallium

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Abstract
Experimental results are presented for wire specimens of high‐purity lead, indium, and thallium which have been plastically deformed at liquid‐helium temperatures and subsequently annealed. The deformation is found to broaden the magnetic transition to the normal state in lead but not in indium or thallium. It is proposed that, for the deformed lead samples in fields larger than the bulk critical field, the superconductivity is confined to small filaments with high defect concentrations. These filaments are restricted to the surface of lightly deformed samples but exist throughout the bulk of heavily deformed samples. It is suggested that the Mendelssohn sponge model is a natural consequence of the Ginzburg‐Landau theory for those inhomogeneous, Type I superconductors which, when homogeneous, have large kappa values. Significant recovery of the strain‐induced resistivity increment is observed below liquid‐nitrogen temperatures for all three metals; at higher temperatures a pronounced recrystallization step is observed in lead but not in indium and thallium. Dislocation‐induced deviations from Kohler's rule were observed in the magneto‐resistivity of lead.