Excitation spectrum of the Hubbard model with infinite electron repulsion on the quasi-one-dimensional orthorhombic lattice

The low-lying energy states of the Hubbard model with infinite electron repulsion on the orthorhombic lattice have been studied. The lattice consisting of two rectangular strips formed by n weakly interacting two-site segments. The stability region of the ferromagnetic ground state in the space of model parameters has been studied by the exact diagonalization of finite lattice clusters. Spin correlation functions have been calculated to clarify the spin structure of the ground state. In the case of cyclic boundary conditions for the lattice with 2n+1 electrons, a separation of charge and spin variables has been obtained.