Perturbations on the superconducting state of metallic nanoparticles:   influence of geometry and impurities
  The pair condensation energy of a finite-size superconducting particle is studied as a function of two control parameters. The first control parameter is the shape of the particle, and the second parameter is a position-dependent impurity introduced in the particle. Whereas the former parameter is known to induce strong fluctuations in the condensation energy, the latter control parameter is found to be a more gentle probe of the pairing correlations. 
Mario Van Raemdonck, Stijn De Baerdemacker, Dimitri Van Neck
cond-mat.supr-con