Monoclinic crystal structure of α − RuCl 3 and the zigzag antiferromagnetic ground state
By R. Johnson, S. Williams, A. Haghighirad, J. Singleton, V. Zapf, P. Manuel, I. Mazin, Ying Li, H. Jeschke, R. Valentí and 1 more. 2015
379 citations recorded by the source corpus.
The layered honeycomb magnet alpha-RuCl3 has been proposed as a candidate to realize a Kitaev spin model with strongly frustrated, bond-dependent, anisotropic interactions between spin-orbit entangled jeff=1/2 Ru4+ magnetic moments. Here we report a detailed study of the three-dimensional crystal structure using x-ray diffraction on untwinned crystals combined with structural relaxation calculations. We consider several models for the stacking of honeycomb layers and find evidence for a crystal structure with a monoclinic unit cell corresponding to a stacking of layers with a unidirectional in-plane offset, with occasional in-plane sliding stacking faults, in contrast with the currently-assumed trigonal 3-layer stacking periodicity. We report electronic band structure calculations for the monoclinic structure, which find support for the applicability of the jeff=1/2 picture once spin orbit coupling and electron correlations are included. We propose that differences in the magnitude of anisotropic exchange along symmetry inequivalent bonds in the monoclinic cell could provide a natural mechanism to explain the spin gap observed in powder inelastic neutron scattering, in contrast to spin models based on the three-fold symmetric trigonal structure, which predict a gapless spectrum within linear spin wave theory. Our susceptibility measurements on both powders and stacked crystals, as well as neutron powder diffraction show a single magnetic transition at TN ~ 13K. The analysis of the neutron data provides evidence for zigzag magnetic order in the honeycomb layers with an antiferromagnetic stacking between layers. Magnetization measurements on stacked single crystals in pulsed field up to 60T show a single transition around 8T for in-plane fields followed by a gradual, asymptotic approach to magnetization saturation, as characteristic of strongly anisotropic exchange interactions.
Subfields: Condensed Matter Physics, Electronic, Optical and Magnetic Materials
View Paper: https://www.semanticscholar.org/paper/fde40ee35244ff6113f910c18bc1187ffccf05ac
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In Condensed Matter Physics
In Electronic, Optical and Magnetic Materials
Citations in the corpus
- Probing and controlling magnetic states in 2D layered magnetic materials (2019, neutral): “In the trihalide RuCl 3 , which has an AF-zigzag ground state 64 , geometric frustration is absent for a honeycomb lattice of Ru 3+ cations (4 d 5 ).”
- Excitations in the field-induced quantum spin liquid state of α-RuCl3 (2017, methodology): “It is known to suppress the magnetic order in α-RuCl3 [8, 9, 21-26] raising the intriguing possibility of a field-induced QSL [20].”
- Crystal and Magnetic Structures in Layered, Transition Metal Dihalides and Trihalides (2017, background): “The moment direction is reported to lie in the monoclinic ac-plane, with components both in and out of the plane of the RuCl3 layers [12,80,90].”
- Kitaev materials (2017, background): “With an eye towards a material realization of the (pure) Kitaev model several experimental signatures have been discussed including the dynamical response [57, 58], whose distinct spectral gap can be probed via inelastic neutron scattering (INS) or electron spin resonance (ESR), the Raman response [”