Clues and criteria for designing Kitaev spin liquid revealed by thermal and spin excitations of honeycomb iridates Na${}_2$IrO${}_3$

Abstract

Contrary to the original expectation, Na${}_2$IrO${}_3$ is not a Kitaev's quantum spin liquid (QSL) but shows a zig-zag-type antiferromagnetic order in experiments. Here we propose experimental clues and criteria to measure how a material in hand is close to the Kitaev's QSL state. For this purpose, we systematically study thermal and spin excitations of a generalized Kitaev-Heisenberg model studied by Chaloupka $et$ $al$. in Phys. Rev. Lett. 110, 097204 (2013) and an effective ab initio Hamiltonian for Na${}_2$IrO${}_3$ proposed by Yamaji $et$ $al$. in Phys. Rev. Lett. 113, 107201 (2014), by employing a numerical diagonalization method. We reveal that closeness to the Kitaev's QSL is characterized by the following properties, besides trivial criteria such as reduction of magnetic ordered moments and Neel temperatures: (1) Two peaks in the temperature dependence of specific heat at $T_{\ell }$ and $T_h$ caused by the fractionalization of spin to two types of Majorana fermions. (2) In between the double peak, prominent plateau or shoulder pinned at $(R/2)\ln 2$ in the temperature dependence of entropy, where $R$ is the gas constant. (3) Failure of the linear spin wave approximation at the low-lying excitations of dynamical structure factors. (4) Small ratio $T_{\ell }/T_h$ close to or less than 0.03. According to the proposed criteria, Na${}_2$IrO${}_3$ is categorized to a compound close to the Kitaev's QSL, and is proven to be a promising candidate for the realization of the QSL if the relevant material parameters can further be tuned by making thin film of Na${}_2$IrO${}_3$ on various substrates or applying axial pressure perpendicular to the honeycomb networks of iridium ions. Applications of these characterization to (Na${}_{1-x}$Li${}_x$)${}_2$IrO${}_3$ and other related materials are also discussed.

16 pages, 16 figures

References in corpus (8)

• 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
• Exact results for spin dynamics and fractionization in the Kitaev Model
• Successive magnetic phase transitions in $\mathbf{\alpha }$-RuCl${}_3$: XY-like frustrated magnet on the honeycomb lattice
• Hidden symmetries of the extended Kitaev-Heisenberg model: Implications for honeycomb lattice iridates A2IrO3
• Importance of anisotropic exchange interactions in honeycomb iridates. Minimal model for zigzag antiferromagnetic order in Na${}_2$IrO${}_3$

Cited by in corpus (78)

• Models and Materials for Generalized Kitaev Magnetism
• Challenges in Design of Kitaev Materials: Magnetic Interactions from Competing Energy Scales
• Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections
• Fermionic response from fractionalization in an insulating two-dimensional magnet
• Hunting Majorana Fermions in Kitaev Magnets
• Possible Kitaev Quantum Spin Liquid State in 2D Materials with S=3/2
• Thermal Transport in the Kitaev Model
• Quantum spin liquid signatures in Kitaev-like frustrated magnets
• Designing Kitaev spin liquids in metal-organic frameworks
• Fingerprints of Kitaev physics in the magnetic excitations of honeycomb iridates
• Thermodynamic evidence of fractionalized excitations in α-RuCl3
• Dynamical and thermal magnetic properties of the Kitaev spin liquid candidate $\alpha$-RuCl${}_3$
• Magnetic thermal conductivity far above the Néel temperatures in the Kitaev-magnet candidate $\alpha$-RuCl${}_3$
• Thermodynamic Evidence of Proximity to a Kitaev Spin-Liquid in Ag${}_3$LiIr${}_2$O${}_6$
• Successive Majorana Topological Transitions Driven by a Magnetic Field in the Kitaev Model
• Ground-state and thermodynamic properties of an $S=1$ Kitaev model
• Thermodynamic properties of the Shastry-Sutherland model throughout the dimer-product phase
• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Path to stable quantum spin liquids in spin-orbit coupled correlated materials
• Quantum spin liquid at finite temperature: proximate dynamics and persistent typicality
• Incipient and well-developed entropy plateaus in spin-S Kitaev models
• Heat capacity evidence for proximity to the Kitaev QSL in A${}_2$IrO${}_3$ ($A=$ Na, Li)
• Experimental signatures of quantum and topological states in frustrated magnetism
• Classical and quantum spin dynamics of the honeycomb $\Gamma$ model
• Emergence of a nematic paramagnet via quantum order-by-disorder and pseudo-Goldstone modes in Kitaev magnets
• Unveiling the S=3/2 Kitaev Honeycomb Spin Liquids
• Majorana-mediated spin transport without spin polarization in Kitaev quantum spin liquids
• Effective model with strong Kitaev interactions for $\alpha$-$\mathrm{RuC}{\mathrm{l}}_3$
• Competing Antiferromagnetic-Ferromagnetic States in $d^7$ Kitaev Honeycomb Magnet
• High-pressure versus isoelectronic doping effect on the honeycomb iridate Na${}_2$IrO${}_3$
• Theory of a quantum spin liquid in hydrogen-intercalated honeycomb iridate, H3LiIr2O6
• Tunneling spectroscopy as a probe of fractionalization in 2D magnetic heterostructures
• Interlayer Coupling Effect on a Bilayer Kitaev Model
• Universal Thermodynamics in the Kitaev Fractional Liquid
• Thermodynamic properties of an $S=1/2$ ring-exchange model on the triangular lattice
• Quantum and classical behavior of spin-$S$ Kitaev models in an anisotropic limit
• Vison-Majorana complex zero-energy resonance in Kitaev's spin liquid
• Nonequilibrium Majorana Dynamics by Quenching a Magnetic Field in Kitaev Spin Liquids
• Majorana spectroscopy of 3D Kitaev spin-liquids
• Spin-Liquid--to--Spin-Liquid Transition in Kitaev Magnets Driven by Fractionalization
• Ground state properties of $\mathrm{N}{\mathrm{a}}_2\mathrm{Ir}{\mathrm{O}}_3$ determined from $\text{ab initio}$ Hamiltonian and its extensions containing Kitaev and extended Heisenberg interactions
• Generic Field-Driven Phenomena in Kitaev Spin Liquids: Canted Magnetism and Proximate Spin Liquid Physics
• Role of the spin-orbit coupling in the Kugel-Khomskii model on the honeycomb lattice
• Topological superconductivity in the extended Kitaev-Heisenberg model
• Quantum Monte Carlo Simulation of Generalized Kitaev Models
• Recent progress on magnetic-field studies on quantum-spin-liquid candidates
• Momentum-independent magnetic excitation continuum in the honeycomb iridate H${}_3$LiIr${}_2$O${}_6$
• Low temperature properties in the Bilayer Kitaev model
• Spin transport in the Quantum Spin Liquid State in the $S=1$ Kitaev model: role of the fractionalized quasiparticles
• Suppression of Antiferromagnetic Order by Strain in Honeycomb Cobaltate: Implication for Quantum Spin Liquid
• Honeycomb oxide heterostructure: a new platform for Kitaev quantum spin liquid
• Thermodynamic evidence for field-angle dependent Majorana gap in a Kitaev spin liquid
• Accuracy of the typicality approach using Chebyshev polynomials
• Incarnation of Majorana Fermions in Kitaev Quantum Spin Lattice
• Dynamics of fractionalized mean-field theories: consequences for Kitaev materials
• Thermally enhanced Majorana-mediated spin transport in the Kitaev model
• Strain-induced phase diagram of the $S=\frac{3}{2}$ Kitaev material $\mathrm{CrSiT}{\mathrm{e}}_3$
• Thermal Pure States for Systems with Antiunitary Symmetries and Their Tensor Network Representations
• Kinetic Ferromagnetism and Topological Magnons of the Hole-Doped Kitaev Spin Liquid
• Longitudinal Magnetization and specific heat of the anisotropic Heisenberg antiferromagnet on Honeycomb lattice
• Finite-Temperature Signatures of Spin Liquids in Frustrated Hubbard Model
• Projective-symmetry-group analysis of inelastic light scattering in Kitaev spin balls
• Ground-state properties for bilayer Kitaev model: dimer expansion study
• Thermal pure matrix product state in two dimensions: tracking thermal equilibrium from paramagnet down to the Kitaev honeycomb spin liquid state
• The ground state in a proximity to a possible Kitaev spin liquid: An undistorted honeycomb iridate NaxIrO3 (0.60 < x < 0.80)
• (H,Li)${}_6$Ru${}_2$O${}_6$ : a possible zero-field Ru${}^{3+}$-based Kitaev Quantum Spin Liquid
• Topological quantum phase transitions of anisotropic AFM Kitaev model driven by magnetic field
• Spin and quadrupole correlations by three-spin interaction in the frustrated pyrochlore magnet Tb${}_{2+x}$Ti${}_{2-x}$O${}_{7+y}$
• Majorana Gap Formation in the Anisotropic Kitaev Model with Ordered Flux Configuration
• Deciphering competing interactions of Kitaev-Heisenberg-$\Gamma$ system in clusters: part I -- static properties
• Optical detection of bond-dependent and frustrated spin in the two-dimensional cobalt-based honeycomb antiferromagnet Cu3Co2SbO6
• A primer on Kitaev Model: Basic aspects, material realization, and recent experiments
• Magnetostriction in the $J$-$K$-$\Gamma$ model: Application of the numerical linked cluster expansion
• Thermodynamic behavior of modified integer-spin Kitaev models on the honeycomb lattice
• Real-space spectral simulation of quantum spin models: Application to generalized Kitaev models
• Emergence of the Isotropic Kitaev Honeycomb Lattice with Two-dimensional Ising Universality in α-RuCl${}_3$
• Magnetic excitations in the Kitaev material Na${}_2$IrO${}_3$ studied by neutron scattering
• Signatures of a Majorana-Fermi surface in the Kitaev magnet Ag${}_3$LiIr${}_2$O${}_6$