Confinement-Engineered Superconductor to Correlated-Insulator Transition in a van der Waals Monolayer.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35167310.
- Also identified by DOI 10.1021/acs.nanolett.1c03491 and PMC identifier 8915256.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Transition metal dichalcogenides (TMDC) are a rich family of two-dimensional materials displaying a multitude of different quantum ground states. In particular, d<sup>3</sup> TMDCs are paradigmatic materials hosting a variety of symmetry broken states, including charge density waves, superconductivity, and magnetism. Among this family, NbSe<sub>2</sub> is one of the best-studied superconducting materials down to the monolayer limit. Despite its superconducting nature, a variety of results point toward strong electronic repulsions in NbSe<sub>2</sub>. 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<sub>2</sub> is in close proximity to a correlated insulating state. This reveals the coexistence of competing interactions in NbSe<sub>2</sub>, 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<sub>2</sub>, establishing NbSe<sub>2</sub> as a correlated superconductor with competing interactions.