Speaker
Description
The search for a quantum spin liquid (QSL) has stimulated substantial research activity within condensed matter physics, particularly following Kitaev’s proposal of his paradigmatic exactly solvable spin model. This model hosts a true QSL ground state and provides an elegant framework for fractionalisation, in which the original spin degrees of freedom decompose into emergent quasiparticles comprising static $\mathbb{Z}_2$ gauge fluxes (visons) and itinerant Majorana fermions. Despite its profound implications for topological quantum computing, a material realisation of the pure Kitaev model has not yet been achieved. This limitation primarily arises from the presence of additional conventional spin interactions, such as Heisenberg and anisotropic Γ exchanges, which compete with the Kitaev term and prevent the system from forming a true QSL state. Nevertheless, depending on the relative strength of the Kitaev interaction, candidate materials may in principle be tuned into a QSL phase through external perturbations such as applied magnetic fields or lattice strain. More recently, cobalt-based quantum magnets have been identified as promising platforms for realising the bond-dependent Kitaev interactions central to this model. One such candidate material, $\text{Li}_3 \text{Co}_2 \text{SbO}_6$, has been reported to exhibit an A-type antiferromagnetic order. By using inelastic neutron scattering (INS) and linear spin wave theory (LSWT), we have phenomenologically extracted the effective coupling parameters of an extended Kitaev–Heisenberg spin model for this compound. The comparatively strong Kitaev exchange inferred from this analysis places $\text{Li}_3 \text{Co}_2 \text{SbO}_6$ as a promising Kitaev spin liquid candidate, despite having an A-type antiferromagnetic ground state. This is in contrast with its sister compound $\text{Na}_3 \text{Co}_2 \text{SbO}_6$, which stabilises a zigzag antiferromagnetic ground state.
| Field of Condensed Matter | Magnetism |
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