2022 Workshop on Recent Developments in Electronic Structure (ES22) Poster Session

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Author: Mark Kamper Svendsen, Technical University of Denmark

Title: Momentum-Dependent Oscillator Strength Crossover of Excitons and Plasmons in Two-Dimensional PtSe2

Abstract: The 1T-phase layered PtX2 chalcogenides has attracted widespread interest due to its thickness dependent metal-semiconductor transition driven by strong interlayer coupling. However, its fundamental excitation spectrum remains poorly understood. Here we combine first principles calculations with momentum (q) resolved electron energy loss spectroscopy (q-EELS) to study the col- lective excitations in 1T-PtSe2 from the mono-layer limit to the bulk. Interestingly, the absence of long-range screening in the two-dimensional (2D) limit, inhibits the formation of long wave-length plasmons. Our work unravels the excited state spectrum of layered 1T-PtSe2 and establishes the qualitatively different momentum dependence of excitons and plasmons in 2D materials

Other authors: Jinhua Hong, Nanomaterials Research Institute, AIST, Tsukuba 305-8565, Japan