Abstract:
We study a strongly correlated fermionic
model with attractive interactions in the
presence of disorder in two spatial
dimensions. Our model has been designed so
that it can be solved using the recently
discovered meron-cluster approach. Although
the model is unconventional it has the same
symmetries as the Hubbard model. Since the
naive algorithm is inefficient, we develop an
algorithm by combining the meron-cluster
technique with the directed-loop update. This
combination allows us to compute the pair
susceptibility and the winding number
susceptibility accurately. We find that the s
-wave superconductivity, present in the clean
model, does not disappear until the disorder
reaches a temperature dependent critical
strength. The critical behavior as a function
of disorder close to the phase transition
belongs to the Berezinky-Kosterlitz-Thouless
universality class as expected. The fermionic
degrees of freedom, although present, do not
appear to play an important role near the
phase transition.