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Direct observation of six-fold exotic fermions in topological semimetal PdSb$_2$

Authors :
Zhipeng, Sun
Chenqiang, Hua
Xiaolei, Liu
Zhengtai, Liu
Mao, Ye
Shan, Qiao
Zhonghao, Liu
Jishan, Liu
Yanfeng, Guo
Yunhao, Lu
Dawei, Shen
Source :
Phys. Rev. B 101, 155114 (2020)
Publication Year :
2019

Abstract

Pyrite-type PdSb$_2$ with a nonsymmorphic cubic structure has been predicted to host six-fold-degenerate exotic fermions beyond the Dirac and Weyl fermions. Though magnetotransport measurements on PdSb$_2$ suggest its topologically nontrivial character, direct spectroscpic study of its band structure remains absent. Here, by utilizing high-resolution angle-resolved photoemission spectroscopy, we present a systematic study on its bulk and surface electronic structure. Through careful comparison with first-principles calculations, we verify the existence of six-fold fermions in PdSb$_2$, which are formed by three doubly degenerate bands centered at the $R$ point in the Brillouin zone. These bands exhibit parabolic dispersion close to six-fold fermion nodes, in sharp contrast to previously reported ones in chiral fermion materials. Furthermore, our data reveal no protected Fermi arcs in PdSb$_2$, which is compatible with its achiral structure. Our findings provide a remarkable platform for study of new topological fermions and indicate their potential applications.

Details

Database :
arXiv
Journal :
Phys. Rev. B 101, 155114 (2020)
Publication Type :
Report
Accession number :
edsarx.1912.00346
Document Type :
Working Paper
Full Text :
https://doi.org/10.1103/PhysRevB.101.155114