96 research outputs found
Robust high-temperature topological excitonic insulator of transition-metal carbides (MXenes)
Topological excitonic insulators combine topological edge states and
spontaneous exciton condensation, with dual functionality of topological
insulators and excitonic insulators. Yet, they are very rare and little is
known about their formation. In this work, we find that a mechanism dubbed as
parity frustration prevents excitonic instability in usual topological
insulators, and those whose band inversion is independent of spin-orbit
coupling are possible candidates. We verify this by first-principles
calculations on monolayer transition-metal carbides (MXenes), which show a
robust thermal-equilibrium exciton condensation, being sufficient for
topological applications at room temperature. Such a state can be identified by
angle-resolved photoemission spectroscopy and transport measurement. Our work
provides not only a guide for finding more topological excitonic insulators,
but also a new platform for studying the interplay between non-trivial band
topology and quantum many-body effects
- …