Polarizability, plasmons, and screening in 1T${^\prime}$-MoS$_2$ with tilted Dirac bands

TL;DR

This paper investigates the electronic screening, plasmon behavior, and polarization properties of 1T' MoS2 with tilted Dirac bands under electric fields and strain, revealing phase transitions and doping effects.

Contribution

It provides a detailed analysis of the dielectric response and plasmon dispersion in 1T' MoS2, incorporating effects of electric field, strain, and spin-orbit coupling, which is novel.

Findings

Identification of phase transition between topological and band insulator states.

Calculation of plasmon dispersion relations and decay rates.

Analysis of impurity screening under various doping and electric field conditions.

Abstract

In the presence of an external vertical electric field and strain, it is evident that 1T${^\prime}$-MoS$_2$ exhibits tilted Dirac bands which are valley-spin-polarized. Additionally, this material experiences a topological phase change between a topological insulator and band insulator for a critical value of the electric field. Using linear response theory, we calculated the polarization function which is in turn employed to obtain the dielectric function. This latter quantity is subsequently utilized in calculations to determine the plasmons dispersion relation, their decay rate and impurity screening corresponding to various levels of doping, the critical applied vertical electric field strengths and the spin-orbit coupling gap in 1T${^\prime}$-MoS$_2$ with tilted Dirac bands.