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arXiv · 2206.13048

Ground-state phase diagram of a spin-1/2 frustrated XXZ ladder

Takuhiro Ogino·Ryui Kaneko·Satoshi Morita·Shunsuke Furukawa
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Abstract

We study the ground-state phase diagram of a spin-$\frac{1}{2}$ frustrated XXZ ladder, in which two antiferromagnetic chains are coupled by competing rung and diagonal interactions, $J_\perp$ and $J_\times$. Previous studies on the isotropic model have revealed that a fluctuation-induced effective dimer attraction between the legs stabilizes the columnar dimer (CD) phase in the highly frustrated regime $J_\perp\approx 2J_\times$, especially for ferromagnetic $J_{\perp, \times}<0$. By means of effective field theory and numerical analyses, we extend this analysis to the XXZ model, and obtain a rich phase diagram. The diagram includes four gapped featureless phases with no symmetry breaking: the rung singlet (RS) and Haldane phases as well as their twisted variants, the RS* and Haldane* phases, which are all distinct in the presence of certain symmetries. Significantly, the Haldane-CD transition point in the isotropic model turns out to be a crossing point of two transition lines in the XXZ model, and the stripe N\'eel and RS* phases appear between these lines. This indicates a nontrivial interplay between the effective dimer attraction and the exchange anisotropy. In the easy-plane regime, the four featureless phases and two critical phases are found to compete in a complex manner depending on the signs of $J_{\perp, \times}$.

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Takuhiro Ogino, Ryui Kaneko, Satoshi Morita, Shunsuke Furukawa. 2022-06-27. Ground-state phase diagram of a spin-1/2 frustrated XXZ ladder. https://doi.org/10.1103/physrevb.106.155106

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