Competing incommensurability, electronic correlations, and superconductivity in a hybrid transition metal dichalcogenide

TL;DR

This study reveals how incommensurate potentials in bulk transition-metal dichalcogenides influence electronic correlations, charge transfer, and superconductivity, unveiling new mechanisms in these complex materials.

Contribution

It demonstrates the presence and effects of incommensurate potentials in bulk TMDs and their impact on electronic phases using combined experimental and theoretical approaches.

Findings

Incommensurate potential modulates interlayer coupling and charge transfer.

Charge redistribution drives the system towards a doped Mott regime.

Bulk superconductivity competes with charge-density-wave order and incommensurate landscape.

Abstract

The engineering of superlattices in two-dimensional van der Waals materials has enabled the realization of rich phase diagrams hosting topological and strongly correlated phases. While incommensurability is widespread in three-dimensional systems, the role of moir\'e potentials in bulk materials remains largely unexplored. Here, using scanning tunneling microscopy, we demonstrate that a bulk transition-metal dichalcogenide polytype, 4Hb-TaS$_2$, hosts an emergent incommensurate potential between its alternating 1T and 1H layers. Interplay with a concomitant incommensurate charge-density wave suppresses the long-range order of this potential, leading to intricate coupling with electronic correlations in the doped 1T surface layer. Combining density functional theory with dynamical mean-field theory, we show that the lattice mismatch locally modulates the interlayer distance, thereby tuning both hybridization and charge transfer between the correlated 1T and metallic 1H layers. This redistribution of charge drives the system towards a doped Mott regime, in which the remaining local moments become self-screened, giving rise to a zero-bias resonance. We further find that bulk superconductivity competes with both the underlying landscape and the associated charge transfer. Our results establish incommensurate potentials as a previously overlooked ingredient in hybrid transition-metal dichalcogenides, highlighting their central role in the interplay between electronic correlations, charge-density-wave order, and unconventional superconductivity.