Excitations of Intercalated Metal Monolayers in Transition Metal Dichalcogenides.

Fan, Shiyu; Neal, Sabine; Won, Choongjae; Kim, Jaewook; Sapkota, Deepak; Huang, Feiting; Yang, Junjie; Mandrus, David G et al. · Nano Lett · 2021

basic_science · Level V

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Abstract

We combine Raman scattering spectroscopy and lattice dynamics calculations to reveal the fundamental excitations of the intercalated metal monolayers in the Fe<sub><i>x</i></sub>TaS<sub>2</sub> (<i>x</i> = 1/4, 1/3) family of materials. Both in- and out-of-plane modes are identified, each of which has trends that depend upon the metal-metal distance, the size of the van der Waals gap, and the metal-to-chalcogenide slab mass ratio. We test these trends against the response of similar systems, including Cr-intercalated NbS<sub>2</sub> and RbFe(SO<sub>4</sub>)<sub>2</sub>, and demonstrate that the metal monolayer excitations are both coherent and tunable. We discuss the consequences of intercalated metal monolayer excitations for material properties and developing applications.