# Gate-tunable flat bands in van der Waals patterned dielectric superlattices

## TL;DR

This paper demonstrates that van der Waals patterned dielectric superlattices can host tunable, robust flat bands controlled by gate voltage, enabling exploration of correlated electronic phenomena without fine tuning.

## Contribution

It introduces a new superlattice platform that creates and switches flat bands on demand using gate voltage, without the need for precise tuning.

## Key findings

- Flat bands can be turned on and off by gate voltage.
- Flat bands exhibit tunable characteristics such as type and localization.
- Enhanced electron-electron interactions enable correlated states.

## Abstract

Superlattice engineering provides the means to reshape the fabric felt by quasiparticles moving in a material. Here we argue that bandstructure engineering with superlattices can be pushed to the extreme limit by stacking gapped van der Waals (vdW) materials on patterned dielectric substrates. Specifically, we find that high quality vdW patterned dielectric superlattices (PDS) realize a series of robust flat bands that can be directly switched on and off by gate voltage in situ. In contrast to existing superlattice platforms, these flat bands are realized without the need for fine tuning. Instead, the bands become flat as the gate voltage increases in magnitude. The characteristics of PDS flatbands are highly tunable: the type of flatband (single non-degenerate or dirac-cone-like), localization length, and interaction energy are sensitive to the applied gate voltage. As a result, electron-electron interactions in the PDS flatbands can become stronger than both the bandwidth and disorder broadening, providing a setting for correlated behavior such as flatband ferromagnetism. We expect PDS flatbands can be experimentally realized in a range of readily available gapped vdW materials such as monolayer transition metal dichalcogenides, e.g. WSe2.