Effect of nonmagnetic impurities on the gap of a dx2-y2 superconductor as seen by angle-resolved photoemission
Abstract
An analysis of angle-resolved photoemission (ARPES) experiments in the superconducting state of the high-Tc copper oxides is presented. It is based on a phenomenological weak-coupling BCS model which incorporates the experimental normal-state dispersion extracted from ARPES, and nonmagnetic impurity scattering in the presence of a dx2-y2 order parameter (OP). It is shown that already in the pure case, the broadening by finite momentum resolution of the analyzer leads to a finite region of apparent ``gaplessness'' around the true node of the OP. Nonmagnetic impurities further amplify this effect by introducing additional spectral weight around zero frequency. At sufficiently large impurity concentrations ni~=0.02-0.05, this results in an extended region of gaplessness up to δφ=+/-7 (φ the angle on the Fermi surface) around the true node for a large range of moderate to strong impurity potential strengths. Different ways to identify the presence of impurity scattering in the ARPES spectra are proposed.
- Publication:
-
Physical Review B
- Pub Date:
- September 1996
- DOI:
- 10.1103/PhysRevB.54.6632
- arXiv:
- arXiv:cond-mat/9603117
- Bibcode:
- 1996PhRvB..54.6632F
- Keywords:
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- Condensed Matter
- E-Print:
- 8 pages uuencoded gzipped Postscript