Anisotropic longitudinal optical conductivities of tilted Dirac bands in 1T$^\prime$-MoS$_2$

TL;DR

This paper theoretically investigates the anisotropic optical conductivities of tilted Dirac bands in 1T'–MoS2, revealing how electric fields and spin-orbit coupling influence topological phase transitions and optical responses.

Contribution

It introduces a theoretical scheme to probe topological phase transitions in 1T'–MoS2 through optical conductivity behaviors, applicable to similar tilted Dirac materials.

Findings

Electric field affects optical conductivity anisotropy.

Spin-orbit coupling gap influences optical responses.

Proposed optical signatures for topological phase transition.

Abstract

1T$^\prime$-MoS$_2$ exhibits valley-spin-polarized tilted Dirac bands in the presence of external vertical electric field and undergoes a topological phase transition between the topological insulator and band insulator around the critical value of the electric field. Within the linear response theory, we theoretically investigate the anisotropic longitudinal optical conductivities of tilted Dirac bands in both undoped and doped 1T$^\prime$-MoS$_2$, including the effects of the vertical electric field. The influence of the spin-orbit coupling gap, band tilting, and vertical electric field on the optical conductivities of tilted Dirac bands is revealed. A theoretical scheme for probing the topological phase transition in 1T$^\prime$-MoS$_2$ via exotic behaviors of longitudinal optical conductivities is proposed. The results for 1T$^\prime$-MoS$_2$ are expected to be qualitatively valid for other monolayer tilted gapped Dirac materials, such as $\alpha$-SnS$_2$, TaCoTe$_2$, and TaIrTe$_4$, due to the similarity in their band structures.