Transforming from Kitaev to Disguised Ising Chain: Application to CoNb$_2$O$_6$
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| Format: | Preprint |
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2024
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| _version_ | 1866912192517898240 |
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| author | Churchill, Derek Kee, Hae-Young |
| author_facet | Churchill, Derek Kee, Hae-Young |
| contents | 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 $JKΓ$ model, has emerged, featuring Heisenberg $(J)$, Kitaev $(K)$, and Gamma $(Γ)$ 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$_{\textrm{eff}}$ = 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 $Γ$ 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. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2403_14754 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Transforming from Kitaev to Disguised Ising Chain: Application to CoNb$_2$O$_6$ Churchill, Derek Kee, Hae-Young Strongly Correlated Electrons 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 $JKΓ$ model, has emerged, featuring Heisenberg $(J)$, Kitaev $(K)$, and Gamma $(Γ)$ 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$_{\textrm{eff}}$ = 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 $Γ$ 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. |
| title | Transforming from Kitaev to Disguised Ising Chain: Application to CoNb$_2$O$_6$ |
| topic | Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2403.14754 |