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

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.

11+16 pages. npj Quantum Materials (in press). Typos (e.g., central charge) are fixed. Some additional results and references will be considered in future

References in corpus (12)

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• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
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• Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling
• Spin-wave excitations evidencing the Kitaev interaction in single crystalline $\alpha$-RuCl${}_3$
• Magnetization processes of zigzag states on the honeycomb lattice: Identifying spin models for $\alpha$-RuCl${}_3$ and Na${}_2$IrO${}_3$
• Theory of the field-revealed Kitaev spin liquid
• Impact of off-diagonal exchange interactions on the Kitaev spin liquid state of $\alpha$-RuCl${}_3$
• Emergence of a nematic paramagnet via quantum order-by-disorder and pseudo-Goldstone modes in Kitaev magnets
• Unveiling the phase diagram of a bond-alternating spin-$\frac{1}{2}$ $K$-$\Gamma$ chain
• Non-Kitaev spin liquids in Kitaev materials

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• Extent of frustration in the classical Kitaev-$\Gamma$ model via bond anisotropy
• Field-induced phase transitions and quantum criticality in a honeycomb antiferromagnet Na3Co2SbO6
• Spontaneous Chiral-Spin Ordering in Spin-Orbit Coupled Honeycomb Magnets
• Spontaneous dimerization, spin-nematic order, and deconfined quantum critical point in a spin-1 Kitaev chain with tunable single-ion anisotropy
• Twice Hidden String Order and Competing Phases in the Spin-1/2 Kitaev-Gamma Ladder
• Interplay of magnetic field and trigonal distortion in the honeycomb $\Gamma$ model: Occurrence of a spin-flop phase
• Strain-induced phase diagram of the $S=\frac{3}{2}$ Kitaev material $\mathrm{CrSiT}{\mathrm{e}}_3$
• Multinode quantum spin liquids in extended Kitaev honeycomb models: the view from variational Monte Carlo
• Chiral spin state and nematic ferromagnet in the spin-1 Kitaev-$\Gamma$ model
• Topological phase transitions and thermal Hall effect in a noncollinear spin texture
• High Chern numbers and topological flat bands in high-field polarized Kitaev magnets on the star lattice
• Anisotropic magnetic interactions in a candidate Kitaev spin liquid close to a metal-insulator transition
• Successive topological phase transitions in two distinct spin-flop phases on the honeycomb lattice
• Interplay of Kitaev Interaction and Off-diagonal Exchanges: Exotic Phases and Quantum Phase Diagrams
• Eleven Competing Phases in the Heisenberg-Gamma (J$\Gamma$) Ladder
• Tunable chiral spiral phases in a non-Hermitian Ising-Gamma spin chain
• Reentrance of metal-insulator transition and magnetic competitions on a triangular lattice with second nearest-neighbor hopping
• Emergent gapless spiral phases and conformal Lifshitz criticality in the cluster Ising model with off-diagonal interactions
• Strategy to Extract Kitaev Interaction using Symmetry in Honeycomb Mott Insulators
• Stabilization of zigzag order in NiPS${}_3$ via positive biquadratic interaction