Broadband excitation spectrum of bulk crystals and thin layers of PtTe$_2$

TL;DR

This study investigates the broadband excitation spectrum of bulk and thin-layer PtTe2 using spectroscopy and theory, revealing unique plasmon behaviors and electronic transitions relevant for optoelectronic applications.

Contribution

The paper provides the first detailed broadband excitation spectrum of PtTe2 and analyzes the thickness-dependent plasmon shifts, combining experimental and theoretical approaches.

Findings

Infrared modes linked to Dirac plasmons and interband transitions identified.

Ultraviolet spectral features observed at 3.9, 7.5, and 19.0 eV.

High-energy plasmon in PtTe2 thin films red-shifts with increasing thickness.

Abstract

We explore the broadband excitation spectrum of bulk PtTe$_2$ using electron energy loss spectroscopy and density functional theory. In addition to infrared modes related to intraband 3D Dirac plasmon and interband transitions between the 3D Dirac bands, we observe modes at 3.9, 7.5 and 19.0 eV in the ultraviolet region. The comparison of the excitation spectrum with the calculated orbital-resolved density of states allows us to ascribe spectral features to transitions between specific electronic states. Additionally, we study the thickness dependence of the high-energy plasmon in the PtTe2 thin films. We show that, unlike graphene, the high-energy plasmon in PtTe2 thin film gets red-shifted by 2.5 eV with increasing thickness.