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We present tight-binding calculations of the electronic states of nanoscopic aluminum particles coated with aluminum oxide. We find that the single-electron energy levels in the neighborhood of the Fermi energy of the particle exhibit clustering, even in the presence of strong disorder at the interface. Our results indicate that the bunching of levels observed experimentally in such particles is influenced strongly by the microscopic details of the structure of the individual sample as well as by many-electron effects.

A tunable two-antidot device is studied in the cyclotron-trapping regime. Periodic quantum oscillations are found to be superimposed on the peaks reminiscent of those observed in antidot lattices. The results are compared to quantum and classical simulations and Feynman path integral analysis. Published by Elsevier Science B.V.

We study the spin singlet superconductivity exhibited in an itinerant Ising model Hamiltonian. This Hamiltonian models the Cu-O layers in highTc oxide superconductors. Electrons are itinerant through nearest neighbor hopping. An Ising term is introduced to describe the antiferromagnetic superexchange interaction between electrons nominally on nearest neighbor Cu sites. We discuss various symmetry states allowed by the model, and give detailed predictions of the superconducting energy gap, specific heat, susceptibility, andTc variation with carrier concentration. Results are compared to experimental data on highTc superconductors and reasonable agreement is obtained.