Kinematic Change in Conduction-Electron Density of States due to Impurity Scattering. II. Problem of an Impurity Layer and Tunneling Anomalies

F. Mezei and A. Zawadowski
Phys. Rev. B 3, 3127 – Published 15 May 1971
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Abstract

The change of the conduction-electron density of states due to electron-impurity scattering has been investigated in a previous paper for one impurity; that calculation is extended now to the case of an impurity layer. A strong momentum dependence of the electron-impurity scattering is assumed, but no restrictions are placed on its energy dependence. Particular attention is paid to the spatial structure of the conduction-electron density of states around the impurity layer, which can be characterized by the same coherence length ξΔ introduced in the case of one impurity. The amplitude of this change shows a smoother dependence on distance measured from the impurity layer than in the case of one impurity, because of some coherent enhancement due to the scattering of different impurities. Therefore, this improves the chances for experimental observations. Theoretical aspects of adequate tunneling experiments on junctions doped by impurities are presented in detail with special emphasis on the determination of the coherence length ξΔ. The perturbations caused by magnetic-impurity scattering is at present of primary interest. Some particular features concerning Kondo scattering and possible connections with giant zero-bias tunneling anomalies are discussed as well. In the case of resonant scattering, the most striking feature is that the conduction-electron-impurity scattering amplitude may be strongly enhanced in the unitarity limit due to the cooperative reduction in the conduction-electron density of states inside the impurity layer at the Fermi energy.

  • Received 11 September 1970

DOI:https://doi.org/10.1103/PhysRevB.3.3127

©1971 American Physical Society

Authors & Affiliations

F. Mezei

  • Central Research Institute for Physics, Budapest, Hungary

A. Zawadowski*,†

  • Department of Physics, University of Virginia, Charlottesville, Virginia 22901

  • *Research supported by the Center for Advanced Studies at the University of Virginia.
  • Permanent address: Central Research Institute for Physics, Budapest, Hungary.

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Vol. 3, Iss. 10 — 15 May 1971

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