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arXiv · 1910.01562

Gapless quantum spin liquid in a honeycomb $\Gamma$ magnet

Qiang Luo·Jize Zhao·Hae-Young Kee·Xiaoqun Wang
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Abstract

A family of spin-orbit coupled honeycomb Mott insulators offers a playground to search for quantum spin liquids (QSLs) via bond-dependent interactions. In candidate materials, a symmetric off-diagonal $\Gamma$ term, close cousin of Kitaev interaction, has emerged as another source of frustration that is essential for complete understanding of these systems. However, the ground state of honeycomb $\Gamma$ model remains elusive, with a suggested zigzag magnetic order. Here we attempt to resolve the puzzle by perturbing the $\Gamma$ region with a staggered Heisenberg interaction which favours the zigzag ordering. Despite such favour, we find a wide disordered region inclusive of the $\Gamma$ limit in the phase diagram. Further, this phase exhibits a vanishing energy gap, a collapse of excitation spectrum, and a logarithmic entanglement entropy scaling on long cylinders, indicating a gapless QSL. Other quantities such as plaquette-plaquette correlation are also discussed.

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Qiang Luo, Jize Zhao, Hae-Young Kee, Xiaoqun Wang. 2019-10-03. Gapless quantum spin liquid in a honeycomb $\Gamma$ magnet. https://doi.org/10.1038/s41535-021-00356-z

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