Upper critical magnetic field of superconducting films with magnetic impurities

Thesis/Dissertation · Wed Jul 05 04:00:00 EDT 1978

DOI:https://doi.org/10.2172/6629015· OSTI ID:6629015

Lemberger, Thomas Richard ^[1]

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1. Univ. of Illinois, Urbana-Champaign, IL (United States)

The upper critical magnetic field, H_c2(T), of In-Mn and Pb-Mn alloy films was measured. H_c2 was determined from the resistance of the films. The results were compared with the theory of Fulde and Maki. 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 H_c2 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 H_c2 for the Pb-Mn alloy films is not well described by the Fulde-Maki theory, probably due to the strong electron-phonon coupling in Pb. 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 some of the Pb-Mn alloy films, there was a region of positive curvature in H_c2(T) near the zero-field transition temperature. This positive curvature is not understood.

• Research Organization: Univ. of Illinois, Urbana-Champaign, IL (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: EY-76-C-02-1198
• OSTI ID: 6629015
• Report Number(s): COO--1198-1213
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
656102 -- Solid State Physics-- Superconductivity-- Acoustic
Electronic
Magnetic
Optical
& Thermal Phenomena-- (-1987)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
CRITICAL FIELD
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
FILMS
INDIUM ALLOYS
LEAD ALLOYS
MAGNETIC FIELDS
MANGANESE ALLOYS
PHYSICAL PROPERTIES
SUPERCONDUCTIVITY
SUPERCONDUCTORS
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE