ÖPG-CMD Joint Meeting 2026

Correlation induced quantum spin Hall insulating state in monolayer TaIrTe₄

Sep 22, 2026, 4:30 PM

30m

HS 15.14 (University of Graz)

4) Invited talk M06 - Interaction effects in correlated systems with higher-order Van Hove singularities and flat bands Mini-Colloquium

Speaker

Honey Boban (Department of Quantum Matter Physics, University of Geneva, Geneva, Switzerland)

Description

Monolayer TaIrTe₄ is theoretically predicted to be a quantum spin Hall insulator [1]. A recent transport study on monolayer TaIrTe4 has confirmed the insulating state at zero doping and reported edge conduction, consistent with a topological insulating state [2]. Intriguingly, a second insulating state with comparable edge conduction was found in gated samples where the chemical potential lies inside the non-interacting conduction band. This second insulating state was attributed to an electronic instability driven by saddle points van Hove singularities in the band structure.
I will present the first micro-focused angle-resolved photoemission spectroscopy (ARPES) results from monolayer TaIrTe₄. Our ARPES results confirm the insulating state of monolayer TaIrTe₄ and directly reveals the presence of van Hove singularities in the band structure.
In addition, I will also present preliminary results from bulk TaIrTe₄ and discuss their consistency with the putative type-II Weyl semimetal state predicted theoretically [3].

References:
[1] P. J. Guo et al., Phys. Rev. B 102, 041109(R), 2020
[2] J. Tang et al., Nature 628, 515–521, 2024
[3] K. Koepernik et al., Phys. Rev. B 93, 201101(R), 2016