Dynamic Order-Disorder Transition in the S = ½ Kagome Antiferromagnets Barlowite and Claringbullite

17 December 2018, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


The nature of the structural phase transition in the quantum magnets barlowite, Cu4(OH)6FBr, and claringbullite, Cu4(OH)6FCl was investigated. These materials consist of parallel-stacked Cu2+ kagome layers, separated by planes that contain Cu2+ cations and halide anions. The structural transition is of an order-disorder type, where at ambient temperature the interlayer Cu2+ ions are disordered over three equivalent positions. In barlowite, the dynamic disorder becomes static as the temperature is decreased, resulting in a lowering of the overall symmetry from hexagonal P63/mmc to orthorhombic. The dynamic disorder in claringbullite persists to lower temperatures, with a transition to orthorhombic space group Pnma observed in some samples. Ab initio density functional theory calculations explain this temperature-dependent structural phase transition and provide additional insights regarding the differences between these two materials.


crystal structure
scanning transmission electron microscopy
ab initio calculation

Supplementary materials

supportingInfo chemarxiv 20181214


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