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The antiferromagnetic solution

A study of the t-t'-U model in the antiferromagnetic phase by means of the COM is reported in Ref. [87]. In particular the following properties have been computed:

  1. The thermodynamic properties (i.e., critical interaction, order parameter: staggered magnetization, internal energy) [87]

  2. The single-particle properties (i.e., energy spectra) [87]

The COM results have been analyzed in relation with the ones obtained by:

We provided simultaneously a fully self-consistent treatment of the paramagnetic and the antiferromagnetic phase. Near half filling the critical value of the Coulomb repulsion as a function of $ t^{\prime}$ and the temperature dependence of the magnetization and internal energy have been studied. $ U_{c}$ turns out to be significantly larger than what obtained by renormalization group techniques [88,89]. This might be due to the fact, that the latter is valid only in the weak coupling limit, whereas COM provides a good approximation for any value of the interaction. The band structure shows the opening of a gap at the transition line between the paramagnetic and the antiferromagnetic phase. With decreasing magnetization the energy increases and reaches the paramagnetic value at vanishing magnetization.


next up previous
Next: The p-d model Up: The t-t'-U model Previous: The paramagnetic solution
avella 2002-06-10