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Formation of clusters in the ground state of the $t-J$ model on a two leg ladder

A. Fledderjohann·A. Langari·K. -H. Muetter
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Abstract

We investigate the ground state properties of the $t-J$ model on a two leg ladder with anisotropic couplings ($t,α=J/t$) along rungs and ($t',α'=J'/t'$) along legs. We have implemented a cluster approach based on 4-site plaqettes. In the strong asymmetric cases $α/α'\ll 1$ and $α'/α\ll 1$ the ground state energy is well described by plaquette clusters with charges $Q=2,4$. The interaction between the clusters favours the condensation of plaquettes with maximal charge -- a signal for phase separation. The dominance of Q=2 plaquettes explains the emergence of tightly bound hole pairs. We have presented the numerical results of exact diagonalization to support our cluster approach.

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A. Fledderjohann, A. Langari, K. -H. Muetter. 2004-10-27. Formation of clusters in the ground state of the $t-J$ model on a two leg ladder. https://doi.org/10.1088/0953-8984%2F16%2F47%2F010

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