Two-particle correlations in finite low-dimensional Hubbard-like lattices

• Published in: Physica. B, Condensed matter Vol. 206; pp. 732 - 735
• Main Authors: Kocharian, A.N., Reich, G.R., Saakian, A.S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-1995
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/0921-4526(94)00570-L

The ground-state properties of two particles (or two holes) with different masses in finite low-dimensional lattices with periodic boundary conditions is investigated rigorously in a Hubbard-like model with external field. A sufficient strong field results in ferromagnetic ordering, and we found the conditions, when the creation of two holes near half-filling for hypercubes in
d = 1, 2, 3 dimensions with even numbers of atoms (for bipartite lattices) and with odd numbers of atoms (for non-bipartite lattices), leads to instability of the ferromagnetic Nagaoka state against spin-flip in the strong interaction limit. The criteria for ferromagnetic stability in lattices consisting of different numbers (odd or even) of particles and lattice sites are also found and represent a qualitative explanation of the strong spontaneous ferromagnetism sometimes seen in small clusters of atoms, such as in rhodium.