Topological, Valleytronic, and Optical Properties of Monolayer PbS

TL;DR

This study explores the topological, valleytronic, and optical characteristics of monolayer PbS, revealing strain-tunable phases and potential for optoelectronic applications with controllable electronic and optical properties.

Contribution

It provides a systematic analysis of PbS monolayers' properties, highlighting strain-induced topological phase transitions and optical methods to manipulate charge, spin, and valley Hall effects.

Findings

Band gaps range from infrared to visible spectrum.

Strain can induce topological phase transitions.

Optical pumping enables control of Hall effects.

Abstract

We systematically examine the topological, valleytronic, and optical properties of experimentally accessible PbS (001) few-layers, with a focus on the monolayer. With even-odd layer-dependent oscillations and without band inversions, the band gaps cover a wide spectrum from infrared to visible, making the few-layers promising for optoelectronics. Intriguingly, the uniaxial (biaxial) compressive strain can tune the trivial monolayer into a $\mathcal{Z}_2$-topological (topological crystalline) insulator, which may be utilized for controllable low-power electronic devices. Although elliptical dichroism vanishes in the monolayer due to inversion symmetry, optical pumping provides an efficient tool to characterize the three phases and to realize charge, spin, and valley Hall effects in optoelectronic transport that are tunable by external strain and light ellipticity.