Stabilizing charge density wave by mixing transition metal elements in monolayer XS$_2$ with trigonal-prismatic coordination

TL;DR

This study investigates how mixing transition metals in monolayer XS$_2$ compounds stabilizes charge density waves, alters electronic properties, and enables a variety of band structures, expanding potential applications in electronics.

Contribution

It introduces high-entropy transition metal mixing in XS$_2$ monolayers as a novel method to stabilize charge density waves and tune electronic properties without large atomic distortions.

Findings

Certain XS$_2$ compounds can be stabilized by charge density waves.

Mixing transition metals creates diverse electronic phases.

High-entropy XS$_2$ compounds exhibit various band structures.

Abstract

The electronic structure and phonon dispersion of XS$_2$ with X = Co, Tc, Ti, Ru, Nb, and Rh in the monolayer MoS$_2$ structure with trigonal-prismatic coordination are studied from first principles. Although each XS$_2$ is dynamically unstable, CoS$_2$, TcS$_2$, RuS$_2$, and RhS$_2$ can be stabilized by developing charge density waves in the (2$\times$2) supercell, leading to metal-insulator transitions. Without really needing the metal-insulator transitions and large atomic distortions, additional energy may be gained in the total energy by mixing transition metal elements to create high-entropy combinations for X, presenting a wide range of high-entropy XS$_2$ compounds that exhibit a variety of band structures, including direct- and indirect-gap semiconductors, metals, and semimetals.