Hourglass Dirac chain metal in rhenium dioxide

作者：Wang, Shan-Shan; Liu, Ying; Yu, Zhi-Ming; Sheng, Xian-Lei^*; Yang, Shengyuan A.^*

来源：Nature Communications, 2017, 8(1): 1844.

DOI：10.1038/s41467-017-01986-3

• TRANSITION
• DISCOVERY
• SEMIMETAL

Nonsymmorphic symmetries, which involve fractional lattice translations, can generate exotic types of fermionic excitations in crystalline materials. Here we propose a topological phase arising from nonsymmorphic symmetries-the hourglass Dirac chain metal, and predict its realization in the rhenium dioxide. We show that ReO2 features hourglass-type dispersion in the bulk electronic structure dictated by its nonsymmorphic space group. Due to time reversal and inversion symmetries, each band has an additional two-fold degeneracy, making the neck crossing-point of the hourglass four-fold degenerate. Remarkably, close to the Fermi level, the neck crossing-point traces out a Dirac chain-a chain of connected four-fold-degenerate Dirac loops-in the momentum space. The symmetry protection, the transformation under symmetry-breaking, and the associated topological surface states of the Dirac chain are revealed. Our results open the door to an unknown class of topological matters, and provide a platform to explore their intriguing physics.

• 出版日期2017-11-29
• 单位北京航空航天大学