arXiv:cond-mat/9710002 · Physical review. B, Condensed matter
Quasiexcitations and superconductivity in the t−J model on a ladder
Ikuo Ichinose, Tetsuo Matsui
Abstract
We study the $t\ensuremath{-}J$ model on a ladder using the slave-fermion-${\mathrm{CP}}^{1}$ formalism that has been used successfully in studying lightly-doped high-${T}_{c}$ cuprates. We obtain a low-energy effective model assuming a short-range antiferromagnetic order (SRAFO), which includes gauge-field degrees of freedom because of the use of the slave-particle picture. We give a systematic study on the dynamics of composite gauge bosons to show that the confinement phase is realized in a two-leg system whereas the deconfinement phase is realized in a chain system. This explains why quasiexcitations are so different in the chain and ladder systems. The effective model also reveals attractive forces between holes, which generate $d$-wave-type superconductive correlations in SRAFO. The low-energy excitations on a ladder are consistently described by the universality class of the Luther-Emery liquid.