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Systematic 1/S study of the 2D Hubbard model at half-filling

A. V. Chubukov·K. A. Musaelian
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Abstract

The 2D Hubbard model is extended by placing 2S orbitals at each lattice site and studied in a systematic 1/S expansion. The 1/S results for the magnetic susceptibility and the spectra of spin-wave excitations at half-filling are consistent with the large S calculations for the Heisenberg antiferromagnet. The 1/S corrections to the fermionic spectrum lift the degeneracy along the edge of the magnetic Brillouin zone yielding minima at (+- pi/2, +- pi/2). Relation to previous papers on the subject is discussed.

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A. V. Chubukov, K. A. Musaelian. 1994-02-22. Systematic 1/S study of the 2D Hubbard model at half-filling. https://doi.org/10.1103/physrevb.50.6238

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