Effect of nonmagnetic impurities on the gap of a {ital d}{sub {ital x}{sup 2}{minus}{ital y}{sup 2}} superconductor as seen by angle-resolved photoemission
- Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany)
An analysis of angle-resolved photoemission (ARPES) experiments in the superconducting state of the high-{ital T}{sub {ital c}} 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 {ital d}{sub {ital x}{sup 2}{minus}{ital y}{sup 2}} 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 {open_quote}{open_quote}gaplessness{close_quote}{close_quote} 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 {ital n}{sub {ital i}}{approx_equal}0.02{endash}0.05, this results in an extended region of gaplessness up to {delta}{phi}={plus_minus}7 ({phi} 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. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 383258
- Journal Information:
- Physical Review, B: Condensed Matter, Journal Name: Physical Review, B: Condensed Matter Journal Issue: 9 Vol. 54; ISSN PRBMDO; ISSN 0163-1829
- Country of Publication:
- United States
- Language:
- English
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