Tuning competing electronic phases in monolayer VSe$_2$ via interface hybridization

TL;DR

This study explores how interface hybridization, charge transfer, and strain influence the electronic phases of monolayer VSe$_2$, revealing tunable transitions between charge density wave states and suppression of order via substrate interactions.

Contribution

It demonstrates the ability to control electronic phases in monolayer VSe$_2$ through interface engineering, strain, and substrate effects, highlighting new pathways for phase manipulation in 2D materials.

Findings

Monolayers on gold show suppressed CDW and moiré patterns.

Bilayers retain bulk-like 4a×4a CDW despite substrate.

Strained, suspended monolayers stabilize a different CDW phase.

Abstract

Competing electronic phases in two-dimensional transition metal dichalcogenides constitute a fertile platform for uncovering emergent ground states and elucidating the control parameters that govern the correlated electron phases. Among these materials, vanadium diselenide is particularly compelling: while the bulk hosts a well-established charge density wave (CDW), monolayers exhibit markedly different electronic behavior. Here, we identify three distinct electronic regimes in mechanically exfoliated VSe$_2$ flakes on Au(111) substrates, where interfacial hybridization, charge transfer, and strain act as primary tuning parameters of electronic order. Monolayers strongly coupled to gold show complete suppression of the CDW, accompanied by the emergence of moir\'e modulations. In contrast, bilayers preserve the in-plane $4a \times 4a$ CDW characteristic of the bulk limit. Strained, electronically decoupled monolayers formed in suspended membrane and bubble regions stabilize a $\sqrt{3}a\times\sqrt{7}a$ CDW phase, underscoring the reversible role of substrate interaction and hybridization.