Strong antiferromagnetic correlation effects on the momentum distribution function of theHubbard model

Abstract

Strong antiferromagnetic correlations can radically change the behavior of an otherwiseparamagnetic system, inducing anomalous effects in the single particle properties anddriving the behavior of spin–spin response functions. In order to investigate such physics,we have studied the momentum distribution function of the two-dimensional Hubbardmodel at low doping, low temperatures and high values of the on-site Coulombrepulsion. The interpretation of the results has greatly benefited from the parallelanalysis of the filling, temperature and interaction dependences of the spin–spincorrelation function, the antiferromagnetic correlation length and the pole of thespin–spin propagator. On reducing doping or temperature and on increasing theinteraction strength, the correlations become stronger and stronger and the Fermisurface develops hole and electron pockets and shows a dual nature (small–large).