Workshop 2025: Theory of Excitonic condensate in monolayer 1T′-WTe

Session Information

Location: Lecture room F3213 - 06
Day: Wednesday, 14 May
Time: 18:00 - 19:00
Chairperson: -

Presentation Details

Presentation Type: Poster presentation
Title: Theory of Excitonic condensate in monolayer 1T′-WTe
Abstract: Monolayer 1T′-WTe2 is known for exhibiting a topological quantum spin Hall insulating (QSHI)
state, characterized by band inversion and strong spin-orbit coupling (SOC), which results in a bulk
insulating gap and spin-momentum-locked conducting edges. However, recent studies question the
microscopic origin of this bulk insulating gap—whether it arises purely from SOC or from electron
correlations, which could lead to the formation of an excitonic condensate, which has been named
as a topological excitonic insulator. In systems with an indirect band gap, the real-space ground
state associated with excitonic bound states can manifest as a charge density wave, spin density
wave, or spin spiral wave, with a wave vector given by valence and conduction band extrema. In this
work, we show that a realistic tight-binding Hamiltonian for the semi-metallic phase of 1T′-WTe2,
including Coulomb interactions, can describe the low energy properties of this monolayer system.
Our results demonstrate the nature of a charge density wave at the conducting edge. We also show
how a gate voltage applied to a substrate layer can be utilized to tune the topological gap and
compare our results with recent scanning tunneling microscopy (STM) experiments on 1T′-WTe2

Presenter

Dr Anirban Das
Post Doctoral Researcher | Hungary

Authors

1. Das, Anirban | Department of theoretical Physics, BME, Hungary, 1111
2. Mukherjee, Shantanu | Department of Physics, IIT Madras, Chennai, India, 600036