Electron tunneling study of superconductors doped with magnetic atoms and nonmagnetic resonant state atoms: Indium-chromium, zinc-manganese, and aluminum-manganese
We have used electron tunneling measurements to determine the density of states of quench-condensed thin films of In-Cr, Zn-Mn, and Al-Mn, and of annealed thin films of Zn-Mn. The results on In-Cr and Zn-Mn were compared with Shiba's theory for magnetic atoms in superconductors. We observed the localized band of states predicted to form in the energy gap of such alloys, though the observed band was broader than that predicted. The annealed samples of Zn-Mn showed a narrower band than did the quench-condensed samples. Reasonable agreement with Shiba's theory was found if s, p, and d wave scattering were included. The results on Al-Mn were compared with Salomaa and Nieminen's theory for nonmagnetic resonant state atoms in superconductors. The predicted band of states was not observed. Our measurements indicate that Mn in quench-condensed Al is nonmagnetic. Any resonant states which do exist in the superconducting alloy are too broad to be seen in our tunneling measurement.
electron tunneling, superconductors doped with magnetic atoms, superconductors nonmagnetic state atoms, wave scattering
University of Illinois - Urbana-Champaign
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