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arXiv · 0812.0593

Origin of the Mott Gap

R. G. Leigh·Philip Phillips
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Abstract

We show exactly that the only charged excitations that exist in the strong-coupling limit of the half-filled Hubbard model are gapped composite excitations generated by the dynamics of the charge $2e$ boson that appears upon explicit integration of the high-energy scale. At every momentum, such excitations have non-zero spectral weight at two distinct energy scales separated by the on-site repulsion $U$. The result is a gap in the spectrum for the composite excitations accompanied by a discontinuous vanishing of the density of states at the chemical potential when $U$ exceeds the bandwidth. Consequently, we resolve the long-standing problem of the cause of the charge gap in a half-filled band in the absence of symmetry breaking.

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R. G. Leigh, Philip Phillips. 2009-06-19. Origin of the Mott Gap. https://doi.org/10.1103/physrevb.79.245120

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