Creation of moir\'e bands in a monolayer semiconductor by spatially periodic dielectric screening

TL;DR

This paper introduces a novel method to create moiré bands in monolayer semiconductors using spatially periodic dielectric screening, enabling tunable superlattice structures without relying on interlayer hybridization.

Contribution

The study demonstrates a new approach to generate moiré bands via dielectric environment engineering in monolayer semiconductors, independent of crystal lattice alignment.

Findings

Moiré bands observed in monolayer WSe₂ near graphene and hBN.

Moiré bands are tunable by gate voltage and dielectric environment.

The method enables versatile superlattice symmetries in monolayer semiconductors.

Abstract

Moir\'e superlattices of two-dimensional van der Waals materials have emerged as a powerful platform for designing electronic band structures and discovering emergent physical phenomena. A key concept involves the creation of long-wavelength periodic potential and moir\'e bands in a crystal through interlayer hybridization when two materials are overlaid. Here we demonstrate a new approach based on spatially periodic dielectric screening to create moir\'e bands in a monolayer semiconductor. It relies on reduced dielectric screening of the Coulomb interactions in monolayer semiconductors and their environmental dielectric-dependent electronic band structure. We observe optical transitions between moir\'e bands in monolayer WSe$_{2}$ when it is placed close to small angle-misaligned graphene on hexagonal boron nitride. The moir\'e bands are a result of long-range Coulomb interactions, strongly gate-tunable, and can have versatile superlattice symmetries independent of the crystal lattice of the host material. Our result also demonstrates that monolayer semiconductors are sensitive local dielectric sensors.