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Journal of Physics Conference Series

Effect of impurity potentials on antiferromagnetism in two-dimensional Hubbard model

Hisatoshi Yokoyama, Ryo Sato, Kenji Kobayashi

Published Jul 1, 2017• 3 citations
Publisher

Abstract

Recent numerical studies have shown that antiferromagnetism (AF) prevails widely near half filling in the two-dimensional Hubbard ( t - t '- U ) model, contrary to the experiments on cuprate superconductors. In cuprates, disorders owing to the dopants, which are usually disregarded in theory, are possibly intrinsic and considerable. Thus, as a first step, we consider the effects of point-type impurity potentials, which are randomly distributed on the lattice sites, on the stability of AF. It is found that a moderate impurity potential does not modify the stability of AF, but a sufficiently strong attractive potential V ( V ≲ − U ) appreciably weakens an antiferromagnetic state owing to an insufficient screening of V .

DOI
10.1088/1742-6596/871/1/012032

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Intrinsic stability as to phase separation of an antiferromagnetic state is studied for a strongly correlated Hubbard model with frustration (t-t’-U model) near half filling, using a variational Monte Carlo method. In the Hartree-Fock (one-body) part of the many-body trial state, band-renormalization effect, which is necessary for partly recovering the nesting condition, is introduced up to three-step hopping distance. As a result, a doped AF state for has a low energy but is unstable toward phase separation, which is consistent with previous studies. In contrast, the AF state becomes stable against phase separation for , owing to the contribution of hopping energy in diagonal directions. The doped AF states are metallic for the two values of , but exhibit contrastive behavior in the momentum distribution function in the nodal and antinodal regions.