Interplay between structure and electronic properties of layered transition-metal dichalcogenides: comparing the loss function of 1T and 2H polymorphs

Physical Review B 90, 205128 (2014)

Interplay between structure and electronic properties of layered transition-metal dichalcogenides: comparing the loss function of 1T and 2H polymorphs

Pierluigi Cudazzo, Matteo Gatti,, Angel Rubio

Transition-metal dichalcogenides (TMD) share the same global two dimensional layered structure, but distinct polymorphs are characterised by different local coordinations of the transition-metal atoms. Here we compared the 1T and 2H families of metallic TMD, both in the bulk and in the two-dimensional forms. By means of first-principles time-dependent density functional calculations of the loss function, we established the direct connection between the low-energy plasmon properties and the crystal-structure symmetry. The different atomic environments affect the d−d electron-hole excitations, which are prominent at low energies, resulting in distinct in-plane plasmon dispersions in the two families. Conversely, the different periodicity of the plasmon reappearance along the c axis perpendicular to the layers can be used to distinguish the various crystal structures of TMD.

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