Abstract:

As is well known, disorder is harmful for a standard BCS superconductor with
d-wave pairing symmetry. Disorder produces excitations at low energies at
points (called nodes) on the Fermi surface where the gap vanishes.
An important puzzle has been the tremendous robustness of these nodes in the
high temperature superconducting materials.
I will show that strong correlations play a vital role in protecting the
nodes and preventing them from getting broadened.
Our results are of direct relevance to recent angle-resolved photoemission
and scanning tunneling spectroscopy experiments.