Piezoelectric Electrostatic Superlattices in Monolayer MoS$_2$

TL;DR

This study demonstrates how electrostatic superlattices in monolayer MoS$_2$ induce structural distortions that significantly alter electronic properties, enabling control over spin-valley coupling for advanced device applications.

Contribution

It reveals the dominant role of structural distortions over electronic effects in electrostatic superlattices and shows how they enable tuning of valley and spin properties in MoS$_2$.

Findings

Electrostatic potentials induce significant structural distortions in MoS$_2$

Distortions reduce the band gap and polarize the monolayer via piezoelectric effects

Minibands inherit valley-selective magnetic properties, enabling control over spin-valley coupling

Abstract

Modulation of electronic properties of materials by electric fields is central to the operation of modern semiconductor devices, providing access to complex electronic behaviors and greater freedom in tuning the energy bands of materials. Here, we explore one-dimensional superlattices induced by a confining electrostatic potential in monolayer MoS$_2$, a prototypical two-dimensional semiconductor. Using first-principles calculations, we show that periodic potentials applied to monolayer MoS$_2$ induce electrostatic superlattices in which the response is dominated by structural distortions relative to purely electronic effects. These structural distortions reduce the intrinsic band gap of the monolayer substantially while also polarizing the monolayer through piezoelectric coupling, resulting in spatial separation of charge carriers as well as Stark shifts that produce dispersive minibands. Importantly, these minibands inherit the valley-selective magnetic properties of monolayer MoS$_2$, enabling fine control over spin-valley coupling in MoS$_2$ and similar transition-metal dichalcogenides.