Finite temperature properties of the 2D Hubbard model extended by next-nearest-neighbor hopping interaction

Abstract

We present an exact diagonalization study on a two dimensional Hubbard model extended by next-nearest-neighbor (NNN) hopping for a small cluster. The thermodynamic properties of spin–spin correlation, local moment, double occupancy, entropy, specific heat are studied for different U and NNN hopping interactions (t′). The increase of NNN hopping interaction favors the formation of doublans and hence decreases local moment in the low temperature region. Transition temperature (Tc) region is identified from entropy curves. Characteristic double peak structure is observed in the specific heat curves with the inclusion of NNN hopping interaction.