Transforming from Kitaev to Disguised Ising Chain: Application to CoNb${}_2$O${}_6$

Abstract

For many years, CoNb${}_2$O${}_6$ has served as an exemplar of the one-dimensional Ising model. However, recent experimental and theoretical analyses challenge its applicability to this material. Prior to that, a tailored spin model for 3d${}^7$ systems such as Co${}^{2+}$, known as the $JK\Gamma$ model, has emerged, featuring Heisenberg $(J)$, Kitaev $(K)$, and Gamma $(\Gamma )$ interactions. While these interactions are permitted by the symmetry of the system, their role in CoNb${}_2$O${}_6$ remains enigmatic. We present a microscopic theory based on spin-orbit entangled J${}_{\text{eff}}$ = 1/2 states, aimed at elucidating the roles of Kitaev and Gamma interactions in shaping Ising anisotropy. Leveraging strong coupling theory, we identify a dominant ferromagnetic Kitaev interaction. Furthermore, by comparing dynamical structure factors obtained via exact diagonalization with those from inelastic neutron scattering experiments, we find an antiferromagnetic $\Gamma$ interaction, which dictates the Ising axis and explains the mechanism behind moment pinning. Our theory suggests that CoNb${}_2$O${}_6$ represents a rare one-dimensional Kitaev chain with significant ferromagnetic Kitaev and antiferromagnetic Gamma interactions.

5 pages, 3 figures

References in corpus (12)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Models and Materials for Generalized Kitaev Magnetism
• Pseudospin exchange interactions in d^7 cobalt compounds: Possible realization of the Kitaev model
• Kitaev-Heisenberg Hamiltonian for High-Spin $d^7$ Mott Insulators
• Energy spectrum of bound-spinons in the quantum Ising spin-chain ferromagnet
• Beyond Kitaev physics in strong spin-orbit coupled magnets
• Non-Kitaev vs. Kitaev Honeycomb Cobaltates
• Experimental Observation of Quantum Many-Body Excitations of $E_8$ Symmetry in the Ising Chain Ferromagnet CoNb${}_2$O${}_6$
• Tuning the confinement potential between spinons in the Ising chain CoNb2O6 using longitudinal fields and quantitative determination of the microscopic Hamiltonian
• Single-ion properties of the transverse-field Ising model material CoNb${}_2$O${}_6$
• Magnon interactions in the quantum paramagnetic phase of CoNb${}_2$O${}_6$
• Excitations of quantum Ising chain CoNb2O6 in low transverse field: quantitative description of bound states stabilized by off-diagonal exchange and applied field

Cited by in corpus (5)

• Emergent SU(2)${}_1$ conformal symmetry in the spin-1/2 Kitaev-Gamma chain with a Dzyaloshinskii-Moriya interaction
• Field-Induced Ordered Phases in Anisotropic Spin-1/2 Kitaev Chains
• Spin-orbit driven $J_{eff}=1/2$ magnetism in a d${}^7$ triangular-lattice monolayer cobaltate
• Spin-basis wavefunctions for the one-dimensional Kitaev model
• Emergent $D_8^{(1)}$ spectrum and topological soliton excitation in CoNb${}_2$O${}_6$