Evidence for metallic 1T phase, 3d1 electronic configuration and charge density wave order in molecular-beam epitaxy grown monolayer VTe2

TL;DR

This study combines experimental and theoretical methods to confirm the metallic 1T phase, 3d1 electronic configuration, and charge density wave order in monolayer VTe2 grown by molecular-beam epitaxy, challenging previous ferromagnetism predictions.

Contribution

It provides direct experimental evidence and theoretical analysis of the electronic structure and charge density wave order in monolayer VTe2, clarifying its magnetic properties.

Findings

Confirmed metallic 1T phase in monolayer VTe2

Identified 3d1 electronic configuration

Observed (4 x 4) charge density wave order

Abstract

We present a combined experimental and theoretical study of monolayer VTe2 grown on highly oriented pyrolytic graphite by molecular-beam epitaxy. Using various in-situ microscopic and spectroscopic techniques, including scanning tunneling microscopy/spectroscopy, synchrotron X-ray and angle-resolved photoemission, and X-ray absorption, together with theoretical analysis by density functional theory calculations, we demonstrate direct evidence of the metallic 1T phase and 3d1 electronic configuration in monolayer VTe2 that also features a (4 x 4) charge density wave order at low temperatures. In contrast to previous theoretical predictions, our element-specific characterization by X-ray magnetic circular dichroism rules out a ferromagnetic order intrinsic to the monolayer. Our findings provide essential knowledge necessary for understanding this interesting yet less explored metallic monolayer in the emerging family of van der Waals magnets.