Motivated by recent reports of a field-induced intermediate phase (IP) in the antiferromagnetic honeycomb Kitaev model that may be a spin liquid whose nature is distinct from the Kitaev ${\mathbb{Z}}_2$ phase, we present a detailed numerical study on the nature and dynamical response (such as dynamical spin-structure factors and resonant inelastic x-ray scattering intensities) of this field-induced IP and neighboring phases in a family of Kitaev-based models related by hidden symmetries and duality transformations. We further show that the same field-induced IP can appear in models relevant for $\alpha -{\mathrm{RuCl}}_3$, which exhibit a ferromagnetic Kitaev coupling and additional interactions. In $\alpha -{\mathrm{RuCl}}_3$, the IP represents a new phase, that is likely independent from the putative field-induced (spin-liquid) phase recently reported from thermal Hall conductivity measurements.

• Received 17 April 2019
• Revised 16 August 2019

DOI:https://doi.org/10.1103/PhysRevB.100.144445