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Existence of the Spin-Wave Gap in a Deformed Flat-Band Hubbard Model

Makoto Homma
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Abstract

We consider a deformed flat-band Hubbard model under a periodic boundary condition in arbitrary dimensions. We show that the ground state is only all-spin-up or -down state. We obtain upper and lower bounds of the one-magnon spin-wave energy with an arbitrary momentum. This dispersion relation is the same as that in the XXZ model in the certain parameter region. Therefore the spin wave has a finite energy gap. These results suggests the our model and the XXZ model.

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Makoto Homma. 2004-11-13. Existence of the Spin-Wave Gap in a Deformed Flat-Band Hubbard Model. https://arxiv.org/abs/cond-mat/0411362

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