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arXiv · 1803.04871

Anisotropic susceptibilities in the honeycomb Kitaev system $\alpha$-RuCl$_{3}$

P. Lampen-Kelley·S. Rachel·J. Reuther·J. -Q. Yan·A. Banerjee·C. A. Bridges·H. B. Cao·S. E. Nagler·D. Mandrus
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Abstract

The magnetic insulator $\alpha$-RuCl$_{3}$ is a promising candidate to realize Kitaev interactions on a quasi-2D honeycomb lattice. We perform extensive susceptibility measurements on single crystals of $\alpha$-RuCl$_{3}$, 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-$\Gamma$ 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 $\Gamma$ spin exchange. The $\Gamma$ couplings and relationships between other terms in the model Hamiltonian are quantified by extracting relevant Curie-Weiss intercepts from the experimental data.

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P. Lampen-Kelley, S. Rachel, J. Reuther, J. -Q. Yan, A. Banerjee, C. A. Bridges, H. B. Cao, S. E. Nagler, D. Mandrus. 2018-03-13. Anisotropic susceptibilities in the honeycomb Kitaev system $\alpha$-RuCl$_{3}$. https://doi.org/10.1103/physrevb.98.100403

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