Magnetization processes of zigzag states on the honeycomb lattice: Identifying spin models for $\alpha$-RuCl${}_3$ and Na${}_2$IrO${}_3$

Abstract

We study the field-induced magnetization processes of extended Heisenberg-Kitaev models on the honeycomb lattice, taking into account off-diagonal and longer-range exchange interactions, using a combination of Monte-Carlo simulations, classical energy minimization, and spin-wave theory. We consider a number of different parameter sets, previously proposed to describe the magnetic behavior of $\alpha$-RuCl${}_3$ and Na${}_2$IrO${}_3$ with their antiferromagnetic zigzag ground states. By classifying these parameter sets, we reveal the existence of three distinct mechanisms to stabilize zigzag states, which differ in the sign of the nearest-neighbor Kitaev interaction, the role of longer-range interactions, and the magnitude of the off-diagonal ${\Gamma }_1$ interaction. While experimentally hardly distinguishable at zero field, we find that the three different scenarios lead to significantly different magnetization processes in applied magnetic fields. In particular, we show that a sizable off-diagonal interaction ${\Gamma }_1>0$ naturally explains the strongly anisotropic field responses observed in $\alpha$-RuCl${}_3$ without the need for a strong anisotropy in the effective $g$ tensor. Moreover, for a generic field direction, it leads to a high-field state with a finite transversal magnetization, which should be observable in $\alpha$-RuCl${}_3$.

15 pages, 9 figures, 1 table; v2: additional comments and references, published version

References in corpus (16)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• $\alpha$-RuCl3: a Spin-Orbit Assisted Mott Insulator on a Honeycomb Lattice
• On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3
• Magnetic order in $\alpha$-RuCl${}_3$: a honeycomb lattice quantum magnet with strong spin-orbit coupling
• Successive magnetic phase transitions in $\mathbf{\alpha }$-RuCl${}_3$: XY-like frustrated magnet on the honeycomb lattice
• Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling
• Spin-wave excitations evidencing the Kitaev interaction in single crystalline $\alpha$-RuCl${}_3$
• Possible proximity of the Mott insulating Iridate Na2IrO3 to a topological phase: Phase diagram of the Heisenberg-Kitaev model in a magnetic field
• Anisotropic Ru3+ 4d5 magnetism in the alpha-RuCl3 honeycomb system: susceptibility, specific heat and Zero field NMR
• Hidden symmetries of the extended Kitaev-Heisenberg model: Implications for honeycomb lattice iridates A2IrO3
• Non-coplanar and counter-rotating incommensurate magnetic order stabilized by Kitaev interactions in $\gamma$-Li2IrO3
• Unconventional magnetic order on the hyperhoneycomb Kitaev lattice in $\beta$-Li2IrO3: full solution via magnetic resonant x-ray diffraction
• Honeycomb-lattice Heisenberg-Kitaev model in a magnetic field: Spin canting, metamagnetism, and vortex crystals
• Spin-S Kitaev model: Classical Ground States, Order by Disorder and Exact Correlation Functions
• Magnetic anisotropy in the Kitaev model systems Na2IrO3 and RuCl3
• Importance of anisotropic exchange interactions in honeycomb iridates. Minimal model for zigzag antiferromagnetic order in Na${}_2$IrO${}_3$

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• Experimental identification of quantum spin liquids
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• Theory of the field-revealed Kitaev spin liquid
• Thermodynamic perspective on the field-induced behavior of $\alpha$-RuCl${}_3$
• Kitaev-like honeycomb magnets: Global phase behavior and emergent effective models
• Magnon damping in the zigzag phase of the Kitaev-Heisenberg-$\Gamma$ model on a honeycomb lattice
• Thermal transport in a two-dimensional ${\mathbb{Z}}_2$ spin liquid
• Floquet engineering of Mott insulators with strong spin-orbit coupling
• Rare-earth chalcohalides: A family of van der Waals layered Kitaev spin liquid candidates
• Observation of a random singlet state in a diluted Kitaev honeycomb material
• Spin-glass state and reversed magnetic anisotropy induced by Cr doping in the Kitaev magnet $\alpha$-RuCl${}_3$
• Universal Thermodynamics in the Kitaev Fractional Liquid
• Susceptibility anisotropy and its disorder evolution in models for Kitaev materials
• Topological superconductivity in the extended Kitaev-Heisenberg model
• Unconventional magnetic field response of the hyperhoneycomb Kitaev magnet $\beta -{\text{Li}}_2{\text{IrO}}_3$