Abstract
We solve the Hubbard model for the case of two particles on an arbitrary Bravais lattice exactly. Although the ground state is almost always a spin singlet, agreeing with the work of Kanamori, for topologically frustrated lattices with positive hopping matrix elements, we find that the ground state is a spin triplet. This topological effect is shown to be rather weak, and does not always survive the jump to finite densities in the thermodynamic limit, where Pauli exclusion strongly stabilises a low spin state. For the two-dimensional triangular lattice and the three-dimensional face-centred cubic lattice, the competition is fiercer and it is not clear whether the ferromagnetism survives.
Original language | English |
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Pages (from-to) | 10343-10358 |
Number of pages | 16 |
Journal | Journal of Physics: Condensed Matter |
Volume | 2 |
Issue number | 51 |
DOIs | |
Publication status | Published - 31 Dec 1990 |