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DOE OSTI · 1804009

Strong polaronic effect in a superatomic two-dimensional semiconductor

Li, Qiuyang·Liu, Fang·Russell, Jake C.·Roy, Xavier·Zhu, Xiaoyang
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Abstract

Crystalline solids assembled from superatomic building blocks are attractive functional materials due to their hierarchical structure, multifunctionality, and tunability. An interesting example is Re 6 Se 8 Cl 2 , in which the Re 6 Se 8 building blocks are covalently linked into two-dimensional (2D) sheets that are stacked into a layered van der Waals solid. It is an indirect gap semiconductor that, when heavily doped, becomes a superconductor at low temperatures. Given the finite electronic bandwidths (300–400 meV), carrier properties in this material are expected to be strongly influenced by coupling to phonons. Here, we apply angle-resolved photoemission spectroscopy to probe the valence band edge (VBE) of Re 6 Se 8 Cl 2 . We find that dispersion of the VBE is a strong function of temperature. The bandwidth is W = 120 ± 30 meV at 70 K and decreases by one order of magnitude to W ~ 10 ± 20 meV as temperature is increased to 300 K. This observation reveals the dominant polaronic effects in Re 6 Se 8 Cl 2 , consistent with the Holstein polaron model commonly used to describe molecular solids.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRYAngle-resolved photoemission spectroscopyChemistryComplex solidsCrystal latticesCrystal structureCrystalline solidsElectronic band structurePhononsPhysicsPolaronsSemiconductorsSuperconductors

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Li, Qiuyang, Liu, Fang, Russell, Jake C., Roy, Xavier, Zhu, Xiaoyang. 2020-05-04. Strong polaronic effect in a superatomic two-dimensional semiconductor. https://doi.org/10.1063/5.0006455

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