Snakes and Ladders

M. A. Martin-Delgado; R. Shankar; G. Sierra

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arXiv · cond-mat/9605035

Snakes and Ladders

M. A. Martin-Delgado·R. Shankar·G. Sierra

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Abstract

We map spin ladders with $n_l$ legs and couplings $J'$ across all rungs and $J(1 \pm γ)$ along the legs, staggered in both directions, to a sigma model. Setting its $θ= (2m+1)π$ (where it is known to be gapless), we locate the critical curves in the $γ$ versus ${J'\over J}$ plane at each $n_l$, and spin $S$. The phase diagram is rich and has some surprises: when two gapped chains are suitably coupled, the combination becomes gapless. With $n_l, γ$ and $J'/J$ to control, the prospects for experimentally observing any one of these equivalent transitions seem bright. We discuss the order parameters and the behavior of holes in the RVB description.

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M. A. Martin-Delgado, R. Shankar, G. Sierra. 1996-05-30. Snakes and Ladders. https://arxiv.org/abs/cond-mat/9605035

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