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arXiv · 2002.04042

Lattice dynamics in the spin-1/2 frustrated kagome compound herbertsmithite

Ying Li·A. Pustogow·M. Bories·P. Puphal·C. Krellner·M. Dressel·Roser Valenti
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Abstract

We investigate the lattice dynamics in the spin-1/2 frustrated kagome compound herbertsmithite ZnCu$_3$(OH)$_6$Cl$_2$ by a combination of infrared spectroscopy measurements and ab initio density functional theory calculations, and provide an unambiguous assignment of infrared-active lattice vibrations involving in-plane and out-of-plane atom displacements in the kagome layers. Upon cooling, non-thermal red-shifts and broadening appear specifically for modes that deform the kagome layer or affect the Cu-O-Cu bond angles, thus creating pronounced modifications of the antiferromagnetic exchange coupling. Our results indicate the presence of a strong magnetoelastic coupling to the spin system. We discuss the effects of this coupling and its relation to recent experiments reporting a global symmetry reduction of the kagome lattice symmetry.

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Ying Li, A. Pustogow, M. Bories, P. Puphal, C. Krellner, M. Dressel, Roser Valenti. 2020-02-10. Lattice dynamics in the spin-1/2 frustrated kagome compound herbertsmithite. https://doi.org/10.1103/physrevb.101.161115

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