Superconductivity due to a repulsive interaction

Project Description: Standard BCS theory states the origin of Type 1 superconductivity is through an attractive interaction due to phonons. The origin of Type 2 superconductivity, or high temperature superconductors, is still unknown. A Hubbard model (which describes many Type 2 superconductors) with U = infinity will be solved, producing a superconducting solution. This will be shown numerically using exact diagonalization and analytically using mean field theory and impurity theory. Once this is shown the limit U = infinity will be lifted using perturbation theory to show the superconductivity strengthen.