Exact low-temperature properties of a class of highly frustrated Hubbard models

Abstract

We study the repulsive Hubbard model both analytically and numerically on a family of highly frustrated lattices which have one-electron states localized on isolated trapping cells. We construct and count exact many-electron ground states for a wide range of electron densities and obtain closed-form expressions for the low-temperature thermodynamic quantities. Furthermore, we find that saturated ferromagnetism is obtained only for sufficiently high electron densities and large Hubbard repulsion $U$ while there is no finite average moment in the ground states at lower densities.

8 pages, 7 figures, accepted for publication in Phys. Rev. B

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• Pairing and superconductivity in quasi one-dimensional flat band systems: Creutz and sawtooth lattices
• Geometrical frustration of an extended Hubbard diamond chain in the quasi-atomic limit
• Low temperature pseudo-phase transition in an extended Hubbard diamond chain
• Semiquantitative theory for high-field low-temperature properties of a distorted diamond spin chain
• Dispersion-driven ferromagnetism in a flat-band Hubbard system
• One-dimensional flat bands and Dirac cones in narrow zigzag dice lattice ribbons
• Trapping Hard-Core Bosons in Flatband Lattices
• Ground-state degeneracy and low-temperature thermodynamics of correlated electrons on highly frustrated lattices
• How to recognize a nearly-flat-band ferromagnet by means of thermodynamic measurements?