paper

Impurity States and the Absence of Quasiparticle Localization in Disordered D-Wave Superconductors

arXiv:cond-mat/9602034 · doi:10.1103/PhysRevLett.76.2386

Abstract

The absence of localization of impurity-induced low-energy quasiparticle states in a two-dimensional -wave superconductor is argued for any amount of disorder in the limit of unitary scatterers. This surprising result follows from the fact that a unitary impurity produces a marginally-bound state at zero energy which decays as a power-law along the nodes of the -wave energy gap. Consequently, for finite density of impurities, the impurity-induced states are coupled by long-range overlaps yielding extended quasiparticle states below a characteristic energy scale . Simple scaling arguments suggest that , where is the impurity density and is a positive constant.

4 pages, uuencoded postscript file

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