Confinement-engineered superconductor to correlated-insulator transition in a van der Waals monolayer

Abstract

Transition metal dichalcogenides (TMDC) are a rich family of two-dimensional materials displaying a multitude of different quantum ground states. In particular, d${}^3$ TMDCs are paradigmatic materials hosting a variety of symmetry broken states, including charge density waves, superconductivity, and magnetism. Among this family, NbSe${}_2$ is one of the best-studied superconducting materials down to the monolayer limit. Despite its superconducting nature, a variety of results point towards strong electronic repulsions in NbSe${}_2$. Here, we control the strength of the interactions experimentally via quantum confinement and use low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS) to demonstrate that NbSe${}_2$ is in close proximity to a correlated insulating state. This reveals the coexistence of competing interactions in NbSe${}_2$, creating a transition from a superconducting to an insulating quantum correlated state by confinement-controlled interactions. Our results demonstrate the dramatic role of interactions in NbSe${}_2$, establishing NbSe${}_2$ as a correlated superconductor with competing interactions.

References in corpus (11)

• Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
• Strongly Correlated Chern Insulators in Magic-Angle Twisted Bilayer Graphene
• Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2
• A quantum phase transition from triangular to stripe charge order in NbSe${}_2$
• Evidence of Spin Frustration in Vanadium Diselenide Monolayer Magnet
• Unexpected two-fold symmetric superconductivity in few-layer NbSe${}_2$
• Ising superconductivity and magnetism in NbSe${}_2$
• Weak Dimensionality Dependence and Dominant Role of Ionic Fluctuations in the Charge-Density-Wave Transition of NbSe${}_2$
• Topological Landscape of Competing Charge Density Waves in 2H-NbSe2
• Observation of superconducting collective modes from competing pairing instabilities in single-layer NbSe${}_2$
• Superconducting parity effect across the Anderson limit

Cited by in corpus (8)

• Evidence of nodal superconductivity in monolayer 1H-TaS${}_2$ with hidden order fluctuations
• Twisted Bogoliubov quasiparticles in the superconducting NbSe${}_2$ monolayer on graphene
• Atomically sharp 1D interfaces in 2D lateral heterostructures of VSe${}_2$-NbSe${}_2$ monolayers
• Doped Mott phase and charge correlations in monolayer 1T-NbSe${}_2$
• Ising and XY paramagnons in two-dimensional 2H-NbSe${}_2$
• Unconventional superconductivity in monolayer transition metal dichalcogenides
• A Theoretical Analysis of Superconducting Pairing in Correlated Metallic Systems
• Josephson junctions of topological nodal superconductors