Antiferromagnetism in the exact ground state of the half-filled Hubbard model on the complete bipartite graph
Antiferromagnetism in the exact ground state of the half-filled Hubbard model on the complete bipartite graph
As a prototype model of antiferromagnetism, we propose a repulsive Hubbard Hamiltonian defined on a graph $\ensuremath{\Lambda}=\mathcal{A}\ensuremath{\cup}\mathcal{B}$ with $\mathcal{A}\ensuremath{\cap}\mathcal{B}=\ensuremath{\emptyset},$ and bonds connecting any element of $\mathcal{A}$ with all the elements of $\mathcal{B}.$ Since all the hopping matrix elements associated with each bond are equal, the model is invariant under an …