GW effects on the topology of type-II Dirac cones in NiTe$_2$, PtSe$_2$ and PtTe$_2$

Abstract

Many-body correlations are known to be responsible for a broad range of fascinating physical phenomena, introducing corrections that appear elusive at the mean-field level. An example of this is the Lifshitz transition that occurs as the Fermi surface topology changes when {\it e.g.} Coulomb interaction effects break into the picture. In particular, the Fermi velocity renormalization can lead a type-II Weyl semimetal at mean-field level to become a trivial or a type-I Dirac material when correlations are accounted for, which is far from being obvious. In this work we scrutinize the band structure of NiTe$_2$, a material that features a type-II Dirac point near the Fermi level within the mean-field approach. Including GW-level correlations, our findings showcase anisotropic corrections on the Dirac carrier velocity exceeding $100 \, \%$ enhancements, underscoring the nuanced influence of electronic interactions in the band structure. We also consider type-II Dirac crossings in PtSe$_2$ and PtTe$_2$ and observe that including many-body effects via GW the band topology changes, featuring trivial topology and type-I Dirac crossings, respectively. Our findings highlights the necessity to evaluate the many-body effects on non-trivial bands, contributing essential insights to the broader exploration of many-body correlation effects in type-II Dirac points of condensed-matter systems.