Impurity States and the Absence of Quasiparticle Localization in Disordered d-Wave Superconductors
Abstract
The absence of localization of impurity-induced low-energy quasiparticle states in a 2D d-wave superconductor is shown for any amount of disorder in the limit of unitary scatterers. This 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 d-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 ωc. Simple scaling arguments suggest that ωc~e-c/nimp, with nimp the impurity density and c a positive constant.
- Publication:
-
Physical Review Letters
- Pub Date:
- March 1996
- DOI:
- 10.1103/PhysRevLett.76.2386
- arXiv:
- arXiv:cond-mat/9602034
- Bibcode:
- 1996PhRvL..76.2386B
- Keywords:
-
- Condensed Matter
- E-Print:
- 4 pages, uuencoded postscript file