# Modulation of electronic structure via dual moiré patterns in twisted 1T-TaSe2

## TL;DR

Researchers discovered that twisting 1T-TaSe2 creates unique electronic patterns that control material properties, offering new ways to study correlated electron behavior.

## Contribution

The study introduces a dual moiré mechanism in twisted 1T-TaSe2 for modulating electronic structure via atomic lattice and CDW superlattice interactions.

## Key findings

- Twisted 1T-TaSe2 exhibits dual moiré patterns from atomic lattice and CDW superlattice interactions.
- The CDW moiré drives an insulator-to-metal transition through twist-induced stacking changes.
- Flat-band pairs with distinct energy gaps emerge from interlayer scattering processes in the moiré system.

## Abstract

This study reveals a unique electronic control mechanism in twisted bilayer 1T-TaSe2, wherein a dual moiré pattern—arising from both the atomic lattice and the charge density wave (CDW) superlattice—governs distinct modulations of the electronic structure. By quantifying the low-energy CDW moiré potential through spectroscopic mapping, the research establishes a framework for understanding flat-band physics in twisted CDW systems. The moiré-tunable electronic states also establish 1T-TaSe2 as a promising platform for exploring correlation effects and competing phases in twisted CDW systems.

We investigate a twisted bilayer of 1T-TaSe2 (twist angle <4°) using scanning tunneling microscopy and spectroscopy, revealing that the coexisting twisted atomic lattice and charge density wave (CDW) superlattice generate a dual moiré structure with distinct electronic modulation effects: The topographic moiré pattern stems from atomic lattice twisting modulating CDW intensity, while the twisted CDW superlattice drives a continuous insulator-to-metal transition, as evidenced by electronic gap evolution from large to metallic states. Density functional theory calculations show this transition arises from twist-induced changes in star of David motif stacking. Using the moiré-period gap map as the interlayer potential V(r), we construct a continuum model via its Fourier components VG, finding that VG mediates multiple interlayer scattering processes that produce numerous superposition states manifesting as split flat-band pairs with distinct energy gaps. This work elucidates a CDW-twist-based mechanism for electronic control in 1T-TaSe2 and provides insights into Mott physics and complex electronic phases in related materials.