The Driving Force of Superconducting Transition in High Temperature Superconductors
We show that both the kinetic energy and the exchange energy of the t-J model can be read off from the optical data. We show that the optical data indicates that the superconducting transition in high temperature superconductors is kinetic energy driven and the exchange energy resist the transition. We also show that kinetic energy may also be the driving force of the pseudogap phenomenon.