Origin of the Mott Gap

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.

6 pages, 2 figures: Expanded Published version

References in corpus (9)

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• Hubbard exciton revealed by time-domain optical spectroscopy
• Driven Imposters: Controlling Expectations in Many-Body Systems
• Doublon-holon binding, Mott transition, and fractionalized antiferromagnet in the Hubbard model
• Charge dynamics of the antiferromagnetically ordered Mott insulator
• Charge 2e Boson Underlies Two - Fluid Model of the Pseudogap in Cuprate Superconductors
• Doublon-holon excitations split by Hund's rule coupling within the orbital-selective Mott phase
• Dynamical slave-boson mean-field study of the Mott transition in the Hubbard model in the large-$z$ limit
• Dynamic charge Kondo effect and a slave fermion approach to the Mott transition
• Non-conservation of Fermionic Degrees of Freedom at Low-energy in Doped Mott Insulators