2023/04/02 by Huaiyuan Yang, Yang, Huaiyuan, Jiaxi Zeng +9 · 1 citation
Physics and Astronomy · #Topological Materials and Phenomena #Cold Atom Physics and Bose-Einstein Condensates #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.2304.00463
Quantum spin-hall insulator (QSHI) processes nontrivial topology. We notice that the electronic structures of some particular QSHIs are favorable for realization of excitonic insulators (EIs). Using first-principles many-body perturbation theory (GW+BSE) and k ⋅ p model, we show that high-temperature (T) topological EIs with unlike spin can exist in such QSHIs with non-vanishing band gaps, e.g. 2D AsO and Mo2TiC2O2. Spin-triplet type EI phase induced by strong electron-hole interaction preserves time-reversal symmetry and the topological characteristics. A novel optical selection rule exists, upon going through the phase transition from the normal QSHIs to the topological EIs, absorption spectroscopy shows pronounced T-dependent changes, providing guidance for future experimental detections. The demonstrated coupling between EIs and topology also means that rich physics exists in such materials which retain such interdisciplinary features.