Ground-State Spin of Hubbard Ladder Model with Infinite Electron Repulsion

V.O. Cheranovskiia, E.V. Ezerskaya a, D.J. Klein b and V.V. Tokarev a aV.N. Karazin Kharkiv National University, Svoboda Sq., 4, 61022 Kharkiv, Ukraine bTexas A&M University at Galveston, Galveston, TX, 77554 USA

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We apply perturbation theory and cyclic spin permutation formalism to study the lowest energy states of the infinite-repulsion Hubbard model on n-leg ladders with alternating values of one-site energies αi for neighboring rungs. We establish the "ferromagnetic" character of ladder ground-state at electron densities in the interval 1 - (2n)-1 ≤ ρ ≤ 1 and sufficiently large alternation of one-site energies of neighbor rungs of the ladder. We also show the stability of this state against the small deviations of the values of αi in contrast to the case of two-leg ladder formed by weakly interacting neighbor rungs with equal one-site energies.

DOI: 10.12693/APhysPolA.131.916 PACS numbers: 71.10.Fd, 75.10.Jm