Tunable plasmons in large area WTe2 thin films

TL;DR

This study demonstrates the growth of large-area WTe2 thin films and the observation of tunable, hyperbolic plasmons that can be controlled by temperature and thickness, opening avenues for advanced plasmonic applications.

Contribution

It reports the scalable synthesis of WTe2 films and the experimental observation of tunable hyperbolic plasmons in films as thin as 8 nm, expanding the potential for topological and plasmonic applications.

Findings

Plasmons observed in large-area WTe2 films down to 8 nm thickness.

Plasmon resonance frequency tunable by temperature and film thickness.

Hybridization of plasmons with substrate phonons mapped and analyzed.

Abstract

The observation of the electrically tunable and highly confined plasmons in graphene has stimulated the exploration of interesting properties of plasmons in other two dimensional materials. Recently, hyperbolic plasmon resonance modes are observed in exfoliated WTe2 films, a type-II Weyl semimetal with layered structure, providing a platform for the assembly of plasmons with hyperbolicity and exotic topological properties. However, the plasmon modes were observed in relatively thick and small-area films, which restrict the tunability and application for plasmons. Here, large-area (~ cm) WTe2 films with different thickness are grown by chemical vapor deposition method, in which plasmon resonance modes are observed in films with different thickness down to about 8 nm. Hybridization of plasmon and surface polar phonons of the substrate is revealed by mapping the plasmon dispersion. The plasmon frequency is demonstrated to be tunable by changing the temperature and film thickness. Our results facilitate the development of a tunable and scalable WTe2 plasmonic system for revealing topological properties and towards various applications in sensing, imaging and light modulation.