1994/05/16 by Didier Poilblanc, D. Poilblanc, Hirokazu Tsunetsugu +2 · 2 citations
Materials Science · Physics and Astronomy · #Organic and Molecular Conductors Research #Physics of Superconductivity and Magnetism #Quantum and electron transport phenomena #cond-mat
paper · pdf · doi:10.1103/physrevb.50.6511
11 pages, 5 figures, uuencoded form of postscript files of figures and text, LPQTH-94/5
arxiv created 1994/05/16 · openalex publication_date 1994/09/01 · arxiv updated 2009/11/30 · openalex created_date 2020/05/13 · openalex updated_date 2026/07/28
Spin gaps in coupled t-J ladders are investigated by exact diagonalization of small clusters up to 4\ifmmode×\else\texttimes\fi8 sites. At half-filling, the numerical results for the triplet excitation spectrum are in very good agreement with a second-order perturbation expansion in terms of small interladder and intraladder exchange couplings between rungs (J/J'0.25). The band of local triplet excitations moving coherently along the ladder (with momenta close to \ensuremathπ) is split by the interladder coupling. For intermediate couplings, finite-size scaling is used to estimate the spin gap. In the isotropic infinite four-chain system (two coupled ladders) we find a spin gap of 0.245J, roughly half of the single-ladder spin gap. When the system is hole doped, bonding and antibonding bound pairs of holes can propagate coherently along the chains and the spin gap remains finite.