Spin susceptibility of the doubly degenerate Hubbard model

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Abstract
It has been shown that the static spin susceptibility of the Hubbard model for a narrow band calculated in the alloy-analogy approximation remains finite for any single-band model and carrier number, except possibly in the case of half-filled bands. In the same way one does not find any instability if one looks for a possible divergence of the susceptibility for a wave vector corresponding to an antiferromagnetic ordering in a half-filled or nearly-half-filled band. In this paper we consider a model with orbital degeneracy. We calculate the spin susceptibility in the alloy-analogy approximation using self-consistent expressions for the configuration probabilities. We investigate how these quantities vary with the model parameters. In this case also we do not find any ferromagnetic instability. The discrepancy with previous results is discussed.