Effective Hamiltonian for a Half-filled Hubbard Chain with Alternating On-site Interactions

Artikel i vetenskaplig tidskrift, 2004

We derive an effective spin Hamiltonian for the one-dimensional half-filled alternating Hubbard model in the limit of strong on-site repulsion. We show that the effective Hamiltonian is a spin S = 1/2 Heisenberg chain with asymmetric next-nearest-neighbour (nnn) exchange.