PAIRING OF HOLES IN THE HUBBARD-MODEL

It is shown that a simple hole created in a singlet state of the strongly correlated Hubbard model, with one electron per atom, can substantially lower the kinetic energy of the system by binding to a spin fluctuation to form a magnetic polaron. Calculations are made for the linear chain, and for the square lattice which relates to the CuO//2 layers in the new oxide superconductors. It is also shown that two simple holes can lower kinetic energy by binding to form a pair. The possibility is considered that two magnetic polarons, fermion-like spin- one-half , may also lower kinetic energy by pairing, thus leading to a type of superconductivity in which the normal state is not a Fermi liquid and where the transition temperature is determined by the bandwidth alone.