Importance of electron correlations in understanding the photo-electron spectroscopy and the Weyl character of MoTe$_2$

TL;DR

This study demonstrates that including electron correlations via Hubbard U in DFT calculations is crucial for accurately describing the electronic structure and Weyl physics of $ ext{MoTe}_2$, aligning theory with experimental observations.

Contribution

The paper shows that electron correlations significantly influence the Weyl features and Fermi surface of $ ext{MoTe}_2$, which was not captured by pure DFT calculations.

Findings

Inclusion of Hubbard U explains the polarization dependence of photoemission.

Electron correlations affect the number and position of Weyl points.

A correlation-induced Lifshitz transition near the Fermi surface is suggested.

Abstract

We study the role of electron correlations in the presumed type II Weyl semimetallic candidate $\gamma$-MoTe$_2$ by employing density functional theory (DFT) where the on-site Coulomb repulsion (Hubbard U) for the Mo 4$d$ states is included within the DFT+U scheme. We show that pure DFT calculations fail to describe important features of the light-polarization dependence of the angular resolved photoemission intensity which can be accounted for by including the role of the Hubbard U. At the same time, while pure DFT calculations cannot explain the angular dependence of the Fermi surface as revealed by quantum oscillation experiments (a fact which had raised doubt about the presence of the Weyl physics in $\gamma$-MoTe$_2$), inclusion of such on-site Coulomb repulsion can. We find that, while the number of Weyl points (WPs) and their position in the Brillouin Zone change as a function of U, a pair of such WPs very close to the Fermi level survive the inclusion of these important corrections. Our calculations suggest that the Fermi surface of $\gamma$-MoTe$_2$ is in the vicinity of a correlations-induced Lifshitz transition which can be probed experimentally and its interplay with the Weyl physics might be intriguing.