Moir\'e Mott correlated mosaics in twisted bilayer 1T-TaS$_2$

TL;DR

This paper explores how twisting bilayer 1T-TaS$_2$ creates mosaic superlattices with tunable correlated insulating phases, combining many-body and single-particle effects influenced by moiré patterns.

Contribution

It demonstrates the formation of twist-dependent mosaic Mott insulators in 1T-TaS$_2$ bilayers and shows how interlayer bias can control their electronic states.

Findings

Mosaic superlattices with magnetic and non-magnetic regions form in twisted 1T-TaS$_2$ bilayers.

The insulating gap depends on stacking and can be modulated by interlayer bias.

The correlated state is tunable, enabling control over charge transfer and magnetic properties.

Abstract

The tunability and twist engineering of van der Waals materials enable the emergence of electronic states not present in individual monolayers. Among them, monolayer 1T-TaS$_2$ is a well-known Mott insulating system, whose star-of-David charge density wave reconstruction realizes an emergent triangular lattice of local magnetic moments. Interestingly, in its bulk form, the insulating gap is not correlation-driven, but stems from interlayer coupling. Here, we exploit the stacking-dependent nature of the insulating gap to show that in twisted 1T-TaS$_2$ bilayers, the spatially dependent competition between many-body and single-particle gaps creates Mott-trivial mosaic superlattices, featuring regions with local magnetic moments and non-magnetic insulating regions. We further demonstrate the tunability of the mosaic correlated state with an interlayer bias, giving rise to controllable charge transfer and quenching of correlations. Our results establish twisted 1T-TaS$_2$ as a flexible platform to engineer mixed spatially modulated correlated insulating phases, arising from the moir\'e profile.