Eur. Phys. J. B 32, 315-322 (2003)
https://doi.org/10.1140/epjb/e2003-00104-9

Antiferromagnetism of almost localized fermions: Evolution from Slater-type to Mott-Hubbard gap

¹ Institute of Physics, Technical University, ulica Podchorążych 1, 30-084 Kraków, Poland
² Marian Smoluchowski Institute of Physics, Jagiellonian University, ulica Reymonta 4, 30-059 Kraków, Poland
³ CNR-IMEM, Unita INFM di Parma, Dipartimento di Fisica, Universita' di Parma, Parco Area delle Scienze 7A, 43100 Parma, Italy
⁴ Commissariat à l'Énergie Atomique, DRFMC/SPSMS, rue des Martyrs, 38054 Grenoble Cedex 9, France

Corresponding author: ^a ufspalek@if.uj.edu.pl

Received: 16 December 2002
Revised: 5 February 2003
Published online: 11 April 2003

Abstract

We supplement (and critically overview) the existing extensive analysis of antiferromagnetic solution for the Hubbard model with a detailed discussion of two specific features, namely (i) the evolution of the magnetic (Slater) gap (here renormalized by the electronic correlations) into the Mott-Hubbard or atomic gap, and (ii) a rather weak renormalization of the effective mass by the correlations in the half-filled-band case, which contrasts with that for the paramagnetic case. The mass remains strongly enhanced in the non-half-filled-band case. We also stress the difference between magnetic and non-magnetic contributions to the gap. These results are discussed within the slave boson approach in the saddle-point approximation, in which there appears a non-linear staggered molecular field due to the electronic correlations that leads to the appearance of the magnetic gap . They reproduce correctly the ground-state energy in the limit of strong correlations. A brief comparison with the solution in the limit of infinite dimensions and the corresponding situation in the doubly-degenerate-band case with one electron per atom is also made.