LOW-TEMPERATURE BEHAVIOR OF THE LARGE-U HUBBARD-MODEL FROM HIGH-TEMPERATURE EXPANSIONS

We derive low-temperature properties of the large-U Hubbard model in two and three dimensions starting from exact series-expansion results for high temperatures. Convergence problems and limited available information prevent a direct or Padé-type extrapolation. We propose a method of extrapolation, which is restricted to large U and low hole densities, for which the problem can be mapped on that of a system of weakly interacting holes. In this formulation an extrapolation down to T=0 can be obtained, but it can be trusted for the presently available series data for t20 and for hole densities nh0.2 only. Implications for the magnetic phase diagram are discussed. © 1995 The American Physical Society.