Phonon dispersion of MoS$_2$

TL;DR

This paper presents the first experimental phonon dispersion relations for bulk MoS$_2$, combining inelastic X-ray scattering with first-principles calculations to enhance understanding of its vibrational properties and support future research.

Contribution

It provides the complete phonon dispersion of bulk MoS$_2$ experimentally measured and theoretically supported, which was previously lacking.

Findings

Phonon dispersion relations determined experimentally for bulk MoS$_2$

Supports the two-dimensional nature of MoS$_2$

Provides phonon displacement patterns and symmetry properties

Abstract

Transition metal dichalcogenides like MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$ have attracted enormous interest during recent years. They are van-der-Waals crystals with highly anisotropic properties, which allows exfoliation of individual layers. Their remarkable physical properties make them promising for applications in optoelectronic, spintronic, and valleytronic devices. Phonons are fundamental to many of the underlying physical processes, like carrier and spin relaxation or exciton dynamics. However, experimental data of the complete phonon dispersion relations in these materials is missing. Here we present the phonon dispersion of bulk MoS$_2$ in the high-symmetry directions of the Brillouin zone, determined by inelastic X-ray scattering. Our results underline the two-dimensional nature of MoS$_2$. Supported by first-principles calculations, we determine the phonon displacement patterns, symmetry properties, and scattering intensities. The results will be the basis for future experimental and theoretical work regarding electron-phonon interactions, intervalley scattering, as well as phonons in related 2D materials.