Unconventional quasiparticle excitations in condensed matter systems have become one of the most important research frontiers. Beyond two- and fourfold degenerate Weyl and Dirac fermions, three-, six- and eightfold symmetry protected degeneracies have been predicted however remain challenging to realize in solid state materials. Here, charge density wave compound TaTe4 is proposed to hold eightfold fermionic excitation and Dirac point in energy bands. High quality TaTe4 single crystals are prepared, where the charge density wave is revealed by directly imaging the atomic structure and a pseudogap of about 45 meV on the surface. Shubnikov de-Haas oscillations of TaTe4 are consistent with band structure calculation. Scanning tunneling microscopy reveals atomic step edge states on the surface of TaTe4. This work uncovers that charge density wave is able to induce new topological phases and sheds new light on the novel excitations in condensed matter materials.
@article{arxiv.2006.16786,
title = {Eightfold Fermionic Excitation in a Charge Density Wave Compound},
author = {Xi Zhang and Qiangqiang Gu and Haigen Sun and Tianchuang Luo and Yanzhao Liu and Yueyuan Chen and Zhibin Shao and Zongyuan Zhang and Shaojian Li and Yuanwei Sun and Yuehui Li and Xiaokang Li and Shangjie Xue and Jun Ge and Ying Xing and R. Comin and Zengwei Zhu and Peng Gao and Binghai Yan and Ji Feng and Minghu Pan and Jian Wang},
journal= {arXiv preprint arXiv:2006.16786},
year = {2020}
}
Comments
Accepted by PRB: https://journals.aps.org/prb/accepted/7907cK4eW0b1ee0b93fd67c1b42942bbb08eafc3c