Applicability of valence-band van Hove arguments to the conduction band

Determine to what degree the arguments concerning van Hove singularities, nesting, and susceptibility enhancements in monolayer 1T-TaIrTe4 apply to the conduction band associated with the many-body quantum spin Hall insulating state.

Background

The measured van Hove singularity occurs in the valence band at a carrier density near that explored in transport experiments, but the corresponding transport data show no reported anomalies. The authors therefore question whether van Hove singularities and nesting are central to the finite-density insulating behavior. They specifically leave unresolved whether this reasoning carries over to the conduction band, where the many-body quantum spin Hall insulating state was observed.

References

At present, it remains open to what degree the above arguments apply to the conduction band where Tang~et al. found the many-body QSHI state.

— Quasi-one-dimensional topological band structure and van Hove singularities in monolayer TaIrTe$_4$ from laser $μ$-ARPES  (2608.20978 - Boban et al., 21 Aug 2026) in Section Main, paragraph beginning “To connect our findings to transport data on gated devices”