Abstract
The magnetic insulator is a promising candidate to realize Kitaev interactions on a quasi-two-dimensional honeycomb lattice. We perform extensive susceptibility measurements on single crystals of , including angle dependence of the in-plane longitudinal and transverse susceptibilities, which reveal a unidirectional anisotropy within the honeycomb plane. By comparing the experimental results to a high-temperature expansion of a Kitaev-Heisenberg- spin Hamiltonian with bond anisotropy, we find excellent agreement with the observed phase shift and periodicity of the angle-resolved susceptibilities. Within this model, we show that the pronounced difference between in-plane and out-of-plane susceptibilities as well as the finite transverse susceptibility are rooted in strong symmetric off-diagonal spin exchange. The couplings and relationships between other terms in the model Hamiltonian are quantified by extracting relevant Curie-Weiss intercepts from the experimental data.
- Received 9 February 2018
- Revised 22 July 2018
DOI:https://doi.org/10.1103/PhysRevB.98.100403
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