The electronic structures and topological properties of the orthorhombic and monoclinic phases of the quasi-one-dimensional excitonic insulator Ta2NiSe5 are investigated based on density functional theory. In contrast to a single parity or band inversion across the Fermi level in many topological insulators studied previously, there are multiple parity and band inversions with or without spin-orbit coupling in both phases of Ta2NiSe5, resulting in more complex and topologically nontrivial electronic structures. The Dirac cone type surface states of the low-temperature monoclinic phase are also obtained. In this paper, we demonstrate that Ta2NiSe5 is a promising candidate as a three-dimensional topological excitonic insulator.
@article{arxiv.2201.07750,
title = {Ta2NiSe5: a candidate topological excitonic insulator with multiple band inversions},
author = {Xiaobo Ma and Guangwei Wang and Huican Mao and Zhihong Yuan and Tianye Yu and Rui Liu and Yiran Peng and Pengyu Zheng and Zhiping Yin},
journal= {arXiv preprint arXiv:2201.07750},
year = {2022}
}