Experimental and theoretical electronic structure and symmetry effects in ultrathin NbSe2 films

Cai Zhi Xu, Xiaoxiong Wang, Peng Chen, David Flötotto, Joseph Andrew Hlevyack, Meng Kai Lin, Guang Bian, Sung Kwan Mo, Tai Chang Chiang

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Layered quasi-two-dimensional transition-metal dichalcogenides (TMDCs), which can be readily made in ultrathin films, offer excellent opportunities for studying how dimensionality affects electronic structure and physical properties. Among all TMDCs, NbSe2 is of special interest; bulk NbSe2 hosts a charge-density-wave phase at low temperatures and has the highest known superconducting transition temperature, and these properties can be substantially modified in the ultrathin film limit. Motivated by these effects, we report herein a study of few-layer NbSe2 films, with a well-defined single-domain orientation, epitaxially grown on GaAs. Angle-resolved photoemission spectroscopy was used to determine the electronic band structure and the Fermi surface as a function of layer thickness; first-principles band-structure calculations were performed for comparison. The results show interesting changes as the film thickness increases from a monolayer (ML) to several layers. The most notable changes occur between a ML and a bilayer, where the inversion symmetry in bulk NbSe2 is preserved in the bilayer but not in the ML. The results illustrate some basic dimensional effects and provide a basis for further exploring and understanding the properties of NbSe2.

Original languageEnglish
Article number064002
JournalPhysical Review Materials
Volume2
Issue number6
DOIs
StatePublished - 20 Jun 2018

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