University of Illinois Urbana-Champaign

Upper critical magnetic field of superconducting films with magnetic impurities

Lemberger, Thomas Richard

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Description

Title
Upper critical magnetic field of superconducting films with magnetic impurities
Author(s)
Lemberger, Thomas Richard
Issue Date
1978
Doctoral Committee Chair(s)
Ginsberg, D.M.
Department of Study
Physics
Discipline
Physics
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
  • upper critical magnetic field
  • superconducting films
  • magnetic impurities
  • Fulde
  • Maki
Language
en
Abstract
We have measured the upper critical magnetic field, H(T), of c2 In-Mn and Pb-Mn alloy films. Hc2 was determined from the resistance of the films. The results were compared with the theory of Fulde and MakL This theory assumes that the electron-phonon coupling is weak, and that the interaction between the impurity spins and the conduction electron spins is weak. The theory predicts that the pair-breaking effect of the magnetic impurities is temperature-independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. Furthermore, it predicts explicitly the temperature dependence of H' c2 The temperature dependence of Hc2 for the In-Mn alloy films is well described by the Fulde-Maki theory, despite. the moderately strong electron-phonon coupling and the strong interaction between the impurity spins and the conduction electron spins. The temperature dependence of Hc2 for the Pb-Mn alloy films is not well described by the Fulde-Maki theory, probably due to the strong electron-phonon coupling in Ph. However, even without a quantitatively correct theory, one can conclude from the Pb-Mn data that the pair-breaking effect of the magnetic impurities is temperature independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. For Home of the Pb-Mn alloy films, there was a region of positive curvature in H(T) near the zero-field transition temperature. This c2 positive curvature is not understood.
Type of Resource
text
Permalink
http://hdl.handle.net/2142/25602
Copyright and License Information
1978 Thomas Richard Lemberger

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