Resonant states and order-parameter suppression near pointlike impurities in d-wave superconductors

Alexander Shnirman, Inanc Adagideli, Paul M. Goldbart, Ali Yazdani

Research output: Contribution to journalArticle

24 Scopus citations

Abstract

We examine the role of order-parameter suppression in the development of low-energy peaks (i.e., resonances) in the tunneling density of states near a nonmagnetic impurity in a d-wave superconductor. Without order-parameter suppression, the zero-energy resonance appears only in the unitary (i.e., strong impurity) limit. However, suppression makes the resonance appear even when the impurity is much weaker. To model this situation, we make the physical hypothesis that the order parameter is reduced whenever one electron of a Cooper pair encounters the impurity, a hypothesis that retains the exact solvability of the problem. In this way, we determine that suppression of the order parameter drives the effective strength of the impurity towards the unitary limit. We determine the order-parameter reduction variationally, and show that the ratios between the main energy scales—the bandwidth and superconducting gap—strongly affect this reduction and, in consequence, the position and width of the resonance.

Original languageEnglish (US)
Pages (from-to)7517-7522
Number of pages6
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume60
Issue number10
DOIs
StatePublished - Jan 1 1999
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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