Pinning of Vortices by impurities in Unconventional superconductors

We carry out a microscopic study of a vortex lattice in a strongly correlated, type-II, d-wave superconductor(SC) using Bogoliubov de Gennes (BDG) formalism. In weak-coupling theory, commonly accepted truism is that a vortex binds to impurity. We demonstrate that in unconventional SCs, the binding of vortex to an impurity depends on relevant parameters. In particular, we illustrate such dependency on the sign of impurity, i.e. attractive or repulsive, as well as doping. We emphasize that this seemingly unanticipated behavior arises from strong correlation effects and is absent in weak coupling descriptions.