Frustration effects at finite temperature in the half filled Hubbard model

Abstract

We investigate the finite temperature properties of the half filled Hubbard model in two dimensions, with onsite interaction (U), in presence of (frustrating) next nearest neighbor hopping (t′) using a semiclassical approximation scheme. We show that introduction of t′ results in a finite temperature pseudogapped (PG) phase that separates the small U Fermi liquid and large U Mott insulator. We map out the PG to normal metal crossover temperature scale (T*) as a function of U and t′. We demonstrate that in the PG phase, the quadratic dependence of resistivity on temperature is violated due to thermally induced spin fluctuations. We conclude with exact diagonalization calculations, that complement our finite temperature results, and indicate the presence of a frustration driven PG state between the Fermi liquid and the Mott insulator at zero temperature as well.