Unveiling MOS2 surface plasmons: an electron energy loss study.

P. BUITRAGO; S. MONTORO; S. RODRIGUEZ; E. ALBANESI; G. RUANO; R. VIDAL; F. BONETTO

Ouro Preto, MG

Encuentro; 2023 Autumn Meeting of the Brazilian Physical Society.; 2023

Brazilian Physical Society

Due to its wide range of applications, molybdenum sulfide (MoS2) has been extensively investigated emerged over the last years. Essentially, these applications are mostly due to a main feature of this material: the weak van der Waals type forces between the MoS2 double layers. A reduction of the material dimension from 3D to 2D and, consequently, a strong modification of its electronic properties is, then, straightforwardly accessible. Surface excitation such as phonons or plasmons are crucial physical ingredients in 2D materials and they can be experimentally studied through electron energy loss spectroscopy. In the present contribution we use Reflected Electron Energy Loss (REELS) with two different incident angles (0º and 30º) and a varying electron incoming energy from 80 to 500 eV to discriminate the electronic losses due to contributions of the volume and the surface of a MoS2 sample. To support the previously obtained results, a comparison is made with the energy loss function (ELF), calculated from first principles within the framework of the Functional Theory of Density, using the plane wave method implemented in the Quantum ESPRESSO (QE) code. Additionally, the analysis is complemented with spectroscopy of photoelectrons emitted by X-rays. In this way, the suitability of the REELS technique and the reliability of the theoretical model to predict the MoS2 properties are determined.